Garden Insects of North America: The Ultimate Guide to Backyard Bugs - Second Edition [Second ed.] 9781400888948

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Second Edition

GARDEN INSECTS OF NORTH AMERICA

THE ULTIMATE GUIDE TO BACKYARD BUGS

Second Edition

GARDEN INSECTS OF NORTH AMERICA

THE ULTIMATE GUIDE TO BACKYARD BUGS

Whitney Cranshaw and David Shetlar

PRINCETON UNIVERSITY PRESS PRINCETON AND OXFORD

To entomology educators and the Cooperative Extension system that so well foster the spirit of shared learning.

Copyright © 2018 by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, 6 Oxford Street, Woodstock, Oxfordshire OX20 1TR nathist.princeton.edu Photographs previous page: left ailanthus moth (Jim Kalisch, University of Nebraska); above, center lizard beetle (Jim Kalisch, University of Nebraska); right bumble bee and a solitary bee (Whitney Cranshaw); below, center “shell” of a cicada nymph discarded at molting (David Shetlar). All Rights Reserved

Library of Congress Cataloging-in-Publication Data Names: Cranshaw, Whitney, author. | Shetlar, David J., author. Title: Garden insects of North America : the ultimate guide to backyard bugs / Whitney Cranshaw and David Shetlar. Description: Second edition. | Princeton, New Jersey : Princeton University Press, 2017. | Includes bibliographical references and index. Identifiers: LCCN 2017013286 | ISBN 9780691167442 (pbk. : alk. paper) Subjects: LCSH: Garden pests—North America—Identification. Classification: LCC SB605.N7 C73 2017 | DDC 635/.0496--dc23 LC record available at https://lccn.loc.gov/2017013286

British Library Cataloging-in-Publication Data is available This book has been composed in Minion Pro (text) and Guess Sans (headings)

Printed on acid-free paper. ∞ Typeset and designed by D & N Publishing, Wiltshire, UK Printed in China 10 9 8 7 6 5 4 3 2 1

CONTENTS Preface Acknowledgments

13 15

CHAPTER one  Introduction to Garden Insects and Their Relatives  16 Arthropod Growth and Metamorphosis

18

Insect Orders

20

Identification of Immature Stages of Arthropods

21

Excreted and Secreted Products Useful in Diagnosing Garden Arthropods and Slugs

Body Parts Useful in Diagnosing Garden Arthropods

30

Common Types of Plant Injuries Caused by Insects

31

Plant Pathogens Transmitted by Insects and Mites

39

28

CHAPTER Two  Insects That Chew on Leaves and Needles 

40

Giant Silkworms/Royal Moths

78 78 78

Grasshoppers

42

Field Crickets

46 46

Other Crickets and Katydids

Common (Northern) Walkingstick Related Species

European Earwig Other Earwigs

50 50 52 52

Cockroaches

54

Imported Cabbageworm

56 56

Other Sulfur and White Butterflies

Swallowtails Parsleyworm/Black Swallowtail Other Swallowtails

Brushfooted Butterflies Painted Lady/Thistle Caterpillar Other Brushfooted Butterflies

Hornworms and Sphinx Moths Tomato Hornworm and Tobacco Hornworm Other Common Hornworms

Prominent Moths/Notodontids Walnut Caterpillar Other Notodontids/Prominent Moths on Shade Trees

58 58 60 62 62 62 68 68 70 74 74 74

Cecropia Moth Other Giant Silkworms/Royal Moths

Slug Caterpillars/Flannel Moths and Other Stinging Caterpillars Tussock Moths Whitemarked Tussock Moth Related and Similar Species

84 86 86 86

Gypsy Moth

90

Woollybears

92

Climbing Cutworms and Armyworms

94 94 94 96 96

Variegated Cutworm Fall Armyworm Beet Armyworm Other Climbing Cutworms and Armyworms

Loopers Cabbage Looper Other Common Garden Loopers

Cankerworms, Inchworms, and Spanworms Fall Cankerworm Other Cankerworms, Inchworms, and Spanworms

102 102 102 104 104 106

Diamondback Moth

110

Skeletonizers

110

CONTENTS Bagworms and Casebearers Bagworm Other Bagworms Casebearers Caterpillars that Produce Cases of Leaf Fragments

Caterpillars that Produce Small Silken Shelters Sod Webworms “Garden Webworms”

Fruittree Leafroller Other Leafrollers, Leaffolders, and Leaftiers

Skippers Caterpillars that Produce Large Silken Shelters and Tents Mimosa Webworm Other Webworms Fall Webworm Eastern Tent Caterpillar Other Tent Caterpillars Other Tent-making Caterpillars

122 122 126

138 142 142 142 146 148 148 150

Sawflies

154 154 154 158 158 164

Other Slug Sawflies

Texas Leafcutting Ant

168

Leafcutter Bees

168

Leaf Beetles Colorado Potato Beetle Asparagus Beetle Related Species Striped Cucumber Beetle Related Species

170 170 172 172 174 174

Other Leaf Beetle Defoliators

176

182

Leaf Beetles that Skeletonize Leaves

184

Leaf Beetles of Aquatic Plants

188

Flea Beetles

190

192 196

Japanese Beetle

202 202

Mexican Bean Beetle Other Leaf-feeding Lady Beetles

204 204

Blister Beetles

206

Slugs and Snails

208 208 208 212 212

Gray Garden Slug Other Garden Slugs Brown Garden Snail Other Garden Snails

Leafminers and Needleminers Vegetable Leafminer Related Species Other Serpentine-type Leafmining Flies and Caterpillars

European Elm Flea Weevil Other Leafmining Weevils

Locust Leafminer Other Blotch Leafmining Beetles

Holly Leafminers Spinach Leafminer Other Leafmining Flies

Birch Leafminer Other Leafmining Sawflies

Lilac Leafminer Other Lepidopteran Leafminers 6

190 192

Leaf-feeding Weevils Other Leaf-feeding Scarabs

166 166

180 180 181

Case-bearing Leaf Beetles

Flea Beetles with Larvae that Develop on Foliage Crucifer Flea Beetle Other Flea Beetles with Larvae that Feed on Roots

128 128

152

Pearslug (Pear Sawfly, Cherry Slug)

Golden Tortoise Beetle Other Common Tortoise Beetles

120

Webspinning Sawflies European Pine Sawfly Other Conifer Sawflies Imported Currantworm/Currant Sawfly Other Common Sawflies Other Sawflies that Chew on Leaves

Tortoise Beetles

114 114 116 118

214 214 214 216 216 218 218 220 220 222 222 226 226 228 228

CONTENTS Tentiform Leafminers

230

Needleminers

232

Gall Wasps that Develop on Leaves

234

Other Gall-making Wasps that Develop on Leaves

236

Gall-making Flies that Develop on Leaves

236

CHAPTER Three  I nsects and Mites That Suck Fluids from Leaves   and Needles 

240

Whiteflies Greenhouse Whitefly Other Whiteflies

Aphids Green Peach Aphid Cotton/Melon Aphid Cabbage Aphid

“Woolly Aphids” Mealybugs Associated Primarily with Foliage Citrus Mealybug Longtailed Mealybug Other Mealybugs Observed on Foliage

Cochineal Scales Soft Scales Associated Primarily with Foliage Brown Soft Scale Other Soft Scales Observed on Foliage

Armored Scales Observed Primarily on Foliage Pine Needle Scale Other Armored Scales Observed on Foliage

Psyllids Potato/Tomato Psyllid Pear Psylla Other Psyllids

Leafhoppers Potato Leafhopper Related Species Rose Leafhopper

Other Mesophyll-feeding Leafhoppers Aster (or Sixspotted) Leafhopper

Miscellaneous Leafhoppers that Feed on Phloem

242 242 242

Leaffooted Bugs Associated with Foliage

248 250 254 254

Squash Bug Related Species

Plant Bugs Fourlined Plant Bug Garden Fleahopper Other Leaf-feeding Plant Bugs

258 260 260 260 262

Hairy Chinch Bug Related and Similar Species

264

276 276 278 278

302

Thrips

304 304 304

Tarsonemid Mites Cyclamen Mite Related Species

282 282 284 284 286 288

310 310 312 312 312 314 316 316 316 318 318 318

False Spider Mites

318

Rust Mites

320

Gall-making Aphids

322 324

Grape Phylloxera 7

298 298

Lace Bugs

Twospotted Spider Mite Related Species European Red Mite Spruce Spider Mite Related Species Clover Mite Related Species Other Turfgrass Mites

270

294 294 294 296

300

Spider Mites

270 270

292 292 292

Stink Bugs that Feed Primarily on Leaves

Onion Thrips Other Thrips Associated with Foliage

266 266 266

288

CONTENTS Other Phylloxeran Leaf Gall Producers Hackberry Nipplegall Maker Other Gall-making Psyllids on Hackberry

324 326 326

Other Psyllids that Distort or Produce Galls on Foliage

Eriophyid Mites that Produce Leaf or Bud Galls

328 328

CHAPTER Four  I nsects Associated with Stems, Twigs, Shoots,   and Canes 

334

European Pine Shoot Moth

368

Other Moths that Develop in Shoots and Terminal Growth of Conifers

White Pine Weevil

334

Woolly Apple Aphid Other Woolly Aphids on Twigs, Branches, and Trunks

334 338

Other Beetles that Develop in Shoots and Terminal Growth of Conifers

338

Flies that Develop in Shoots and Twigs of Conifers

342

Adelgids that Develop on Twigs and Terminals of Conifers Hemlock Woolly Adelgid Other Adelgids Associated with Twigs and Terminals of Conifers

Mealybugs Associated Primarily with Stems and Twigs

Moths that Develop in Shoots, Twigs, and Canes of Deciduous Trees and Shrubs 342 Rose Shoot Sawfly and Raspberry Horntail Other Sawfly Shoot and Stem Borers

Rednecked Cane Borer Related Species

Other Beetles Associated with Twigs and Small Branches

Eriococcid Scales Commonly Observed on Twigs

346 346

European Elm Scale Other Eriococcid Scales

348 348

Soft Scales Observed Primarily on Twigs European Fruit Lecanium Other Lecanium-type Soft Scales Striped Pine Scale Related and Similar Species Cottony Maple Scale Other Soft Scales Associated Primarily with Twigs

350

Flies that Develop in Shoots, Twigs, and Canes of Deciduous Trees and Shrubs 356 Squash Vine Borer

356

European Corn Borer

358

Other Stem-boring Moths of Herbaceous Plants

358

Margarodid Scales Associated Primarily with Twigs

Sawflies that Develop in Stems of Herbaceous Plants

360

Beetles that Develop in Stems of Herbaceous Plants

362

Flies that Develop in Stems of Herbaceous Plants

Armored Scales that Develop Primarily on Small Branches and Twigs

364

Pith-nesting Bees and Wasps

364

Aphids that Develop on Stems, Twigs, Shoots, and Canes

Oystershell Scale Other Armored Scales Associated with Twigs and Branches

366

Cottony Cushion Scale Other Margarodid Scales

Kermes, Pit, and Falsepit Scales 8

368 370 370 370 372 374 374 376 378 378 378 380 382 382 384 386 386 386 388 388 390 394

CONTENTS Spittlebugs

396

Planthoppers

400

Treehoppers

402 402 402

Buffalo Treehopper Other Treehoppers

Cicadas

Gall Wasps Associated with Twigs and Small Branches Oak Rough Bulletgall Wasp Related Species Horned Oak Gall Wasp Related Species Rose Gall Wasps Other Gall Wasps

406 406 408

Periodical Cicadas Other Cicadas

Twig Wounding Produced by Egg Laying and Oviposition Injuries

Flies and Caterpillars that Produce Galls in Stems and Twigs

410

Cooley Spruce Gall Adelgid Other Gall-making Adelgids

CHAPTER Five

Insects Associated with Large Branches and the Trunk of Trees and Shrubs

Clearwing Borers Ash/Lilac Borer Other Clearwing Borers Associated with Trunks and Branches

Carpenterworm Other Carpenterworms

Zimmerman Pine Moth Other Pyralid Borers

Metallic Wood Borers/Flatheaded Borers Bronze Birch Borer Emerald Ash Borer Related Species Flatheaded Appletree Borer Related Species

Longhorned Beetles/Roundheaded Borers Locust Borer Related Species Poplar Borer

CHAPTER Six

424 424

Related Species Other Longhorned Beetles Commonly Found in Trees and Shrubs

426

Poplar and Willow Borer

428 428

Other Trunk-boring Weevils

Horntails

430 430

Pigeon Tremex Other Horntails

432 432 434 436 438 438

Bark Beetles Shothole Borer Related Species Smaller European Elm Bark Beetle Other Elm Bark Beetles Ash Bark Beetles Southern Pine Beetle and Relatives Ips Beetles

440 440 440 442

Ambrosia Beetles

Insects and Other Invertebrates Associated with Roots, Tubers, Soil, and the Soil Surface

White Grubs Northern Masked Chafer Related Species

464 464 466

410 412 412 414 414 416 416 418 422 422

424 442 444 448 448 450 450 450 452 452 452 454 454 456 456 458 460

464

Other White Grubs Associated with Turfgrass 466 White Grubs Associated Primarily with Garden Plants 470 9

CONTENTS Root Weevils Black Vine Weevil Other Root-damaging Weevils Sweetpotato Weevil Other Vegetable Weevils

Bluegrass Billbug Other Billbugs

472 472 472 476 476

480

Western Corn Rootworm

482

Other Leaf Beetles that Develop on Roots and Tubers

486

Iris Borer

488 488

Other Crown-boring Caterpillars

494

Roundheaded Borers that Feed on Roots

498

Root Maggots and Bulb Flies

500 500 500 502 502

Cabbage Maggot Other Root Maggots Narcissus Bulb Fly Other Bulb Flies

504

Other Small Flies Associated with Indoor Plant Production

Flies Associated with Decaying Organic Matter and Compost Mole Crickets Tawny Mole Cricket Other Crickets Associated with Soil

Subterranean and Surface-feeding Cutworms 492 Black Cutworm 492 Other Surface-feeding and Subterranean Caterpillars

European Crane Fly

Fungus Gnats

482

Peachtree Borer

504

Other Flies Associated with the Root Area of Turfgrass

478 478

Wireworms

Carrot Rust Fly

Related Species

Oriental Fruit Moth Related Species

Tobacco Budworm Related Species

Corn Earworm/Tomato Fruitworm/ Bollworm Other Fruit-infesting Cutworms

Pickleworm Related Species

508 510 512 512 512 516

Ants

518 518 520

Red Imported Fire Ant Other Ants Common in Yards and Gardens

542 542

508

Subterranean Termites

Root Aphids and Other Sucking Insects

526

Sowbugs and Pillbugs

530

Other Land-adapted Crustaceans

530

Millipedes

532

Springtails

534

Symphylans

536

Soil-dwelling Mites

536

Earthworms

538

CHAPTER Seven  I nsects and Mites Associated with Flowers,   Fruits, Nuts, and Seeds  Codling Moth

506

542

Other Fruit- and Seed-infesting Caterpillars 554 Fruit-infesting Sawflies

544 544

Related Species

Scarab Beetles Found at Fruit and Flowers

546 546

Sap Beetles and other Fruit-damaging Beetles Dusky Sap Beetle Other Sap Beetles Other Fruit-damaging Beetles

548 548 550 550

Pollen-feeding Beetles Common at Flowers 10

558 558 558 562 562 562 564 566

CONTENTS

 

Fruit, Flower, and Seed Weevils Plum Curculio Rose Curculio and Western Rose Curculio Other Seed-, Fruit-, and Flower-damaging Weevils

Fruit Flies Apple Maggot Related Fruit-infesting Flies

Spotted-wing Drosophila Other Vinegar Flies and Small Fruit Flies

Rose Midge Other Gall Midges Damaging to Buds, Flowers and Fruit

Yellowjackets and Hornets Western Yellowjacket Other Yellowjackets and Hornets

568 568 570

Gall Wasps Affecting Nuts

588

Western Flower Thrips

590 590

Related Species

Tarnished Plant Bug

570

Related Species

576 576 576

Brown Marmorated Stink Bug Other Stink Bugs that Feed on Flowers, Fruit, and Seeds

580 582

Boxelder Bug Related and Similar Species

582

Western Conifer-seed Bug Related Species

584 586 586 586

Lady Beetles (Ladybugs, Ladybird Beetles) Ground Beetles Rove Beetles Soldier Beetles Blister Beetles Fireflies/Lightningbugs Soft-winged Flower Beetles Clerid Beetles Cybocephalid Beetles Green Lacewings Brown Lacewings Dustywings Antlions Syrphid Flies (Flower Flies, Hover Flies) Predatory Midges Longlegged and Dance Flies Robber Flies Bee Flies Predatory Thrips Predatory Stink Bugs

610 610 614 616 616 618 618 618 620 620 620 622 622 622 624 624 626 626 628 628 628

595 598 598 602 602 604

Eriophyid Mites that Damage Fruits and Flowers

606

Assassin Bugs Damsel Bugs Predatory Plant Bugs Big-eyed Bugs Minute Pirate Bugs Mantids Earwigs Dragonflies and Damselflies Crab Spiders Jumping Spiders Wolf Spiders Nursery Web Spiders Dysderid Spiders Orbweavers Longjawed and Orchard Orbweavers Cobweb Weaver Spiders Lynx Spiders Funnel Weavers Prowling Spiders Cellar Spiders Brown or Recluse Spiders 11

594

Scales and Mealybugs Associated with Fruit Injuries

CHAPTER Eight  N   atural Enemies of Insects and Pollinators:  The “Beneficial Bugs”  Predators of Insects and Mites

592 592

608 630 630 632 632 632 634 636 636 636 638 638 638 640 640 642 644 644 646 646 648 648

CONTENTS Daddy Longlegs/Harvestmen Predatory Mites Centipedes Predatory Snails

Hunting Wasps and Ants Predatory Ants Paper Wasps Hornets and Yellowjackets Potter Wasps Hunting Wasps Spider Wasps

Insect Parasitoids Tiphiid and Scoliid Wasps

648 650 652 652

Pelecinid Wasps Ichneumonid Wasps Braconid Wasps Chalcid Wasps Sarcophagid Flies Tachinid Flies

654 654 654 656 656 658 660

Glossary Index

660 662 662 664 666 666

Insect Pathogens

668

Bees

672 672 674 674 676 678

Honey Bee Bumble Bees Large Carpenter Bees Cavity-nesting Bees Soil-nesting Bees

660 660

 

682 688

12

PREFACE Well over 100,000 species of insects and other arthropods are known to exist in North America, and the scope of this book is necessarily limited. Emphasis herein is on those “garden bugs” that are most likely to be encountered in a yard and garden, particularly those that injure plants. Selecting which insects, mites, and other “garden bugs” to include—and perhaps more importantly which not to include—has involved many judgment calls. For example, many insects restricted primarily to forests, grasslands, waters, or other natural areas overlap in their presence and activity in yard and garden settings. In this second edition of Garden Insects of North America a great many changes have been made. Perhaps most obvious is the greatly increased number (and quality) of images, reflecting the enormous changes that have occurred with photography of insects since 2004. But the number of species included in this edition has also greatly expanded. This expansion has occurred throughout the book, but some sections are either completely new or have been given greatly expanded treatment. This new treatment is particularly evident in chapter 8, which discusses natural enemies of insects and mites along with important pollinator species of bees. The expanded treatments in this second edition have been made possible by making this a coauthored publication, involving the complementary experiences of both Whitney Cranshaw and David Shetlar.

ORGANIZATION Garden Insects of North America is designed to provide a means to identify the types of insects one might find in a yard and garden and to diagnose their presence based on associated symptoms they may produce on plants. To best achieve this approach, we adopted an organization that is a hybrid of ways that other books on insect identification are organized. In Garden Insects of North America the primary groupings involve the parts of plants where one might most often notice insects. For examples, chapters 2 and 3 cover insects found on leaves and needles, chapter 4 the insects that occur on twigs, stems, and canes, and chapter 5, insects associated with larger branches and the trunks of trees. Chapter 6 covers the broad subject area of insects, mites, and other arthropods one might see feeding on roots, at the soil level, or developing within the soil. Chapter 7 deals with insects and mites found in or on flowers, fruits, seeds, and nuts. Chapter 8 has a different focus, covering the natural enemies of insects and one group of important flower-visiting pollinators, the bees. Within these main chapters, the associated insects (and other garden “bugs”) are usually organized by taxa, to the genus level whenever appropriate; however, we have made an effort to place insects together in the text that have somewhat similar appearance or habit. For example, mealybugs are placed near related groups such as “woolly” aphids and soft scales. Also, the caterpillars of many families of moths and skippers form protective shelters of silk, frass, or leaf fragments, or combinations of these, and these are grouped. At the end of each section, classification to the order and family level is noted. For example, following discussion of the peach tree borer there is the notation “Lepidoptera: Sesiidae” to indicate that the peach tree borer is in the order Lepidoptera (moths and butterflies) and the family Sesiidae (clearwing borers). The diversity of insect habits clearly defies easy grouping. For example, western corn rootworm develops as a root-feeding larva on corn plants, then feeds on leaves and flowers of a wide variety of plants as an adult. Japanese beetle is a first-class problem in turfgrass, where it develops underground as a white grub, but later as an adult that 13

PREFACE feeds on leaves and flowers of many garden plants. Such “crossover” species are treated primarily in one section (western corn rootworm as an insect that develops on plant roots, Japanese beetle as an insect that chews on leaves), but where such insects occur there are cross-references and treatments in other chapters.

COMMON NAMES Throughout the book we often use common names, concurrently defined with a scientific name (genus, species). When we decided to use a common name, we always gave precedence to names accepted by the Entomological Society of America, which has a long-established procedure for formalizing common names of insects. For many insects and their relatives, however, there are not yet any officially recognized common name. Where this occurs, often one or more names have been proposed in other publications. Some of these are used in this book. Ultimately all such common names should be formally proposed and, where acceptable, recognized by the Entomological Society of America and Entomological Society of Canada.

14

ACKNOWLEDGMENTS This second edition of Garden Insects of North America builds on the original 2004 edition. At that time we acknowledged dozens of colleagues and resources who allowed this project to begin, and their contributions continue to be carried forward in this edition. A wide variety of individuals and organizations have also been involved in the changes reflected in this revision, and some of them need special acknowledgment. In the past 13 years there have been wonderful improvements in both quality and accessibility of fact sheets and research reports provided by state programs associated with Cooperative Extension, state IPM programs, and the USDA Forest Service; these have been extensively reviewed in the development of this project. In addition, a “new” resource that has been exceptionally useful is BugGuide.Net, hosted at Iowa State University and currently maintained by John VanDyk. This website offers an enormous number of arthropod images and is well curated through the contributions of entomology specialists throughout the continent. Along with the multiple images it provided to illustrate features of almost every species included in this book, the details on insect distribution and classification were particularly valuable. Perhaps the most significant change in the second edition is the large increase in the number of images. Although many of these were taken by the authors, the majority are contributions from more than 100 individuals and organizations. Once again, BugWood.org, now known as the Center for Invasive Species and Ecosystem Health, based at the University of Georgia, has been a critical resource for identifying images and providing contact with cooperators. These are acknowledged where the photographs are used throughout the book, but some contributors who have been particularly helpful in the success of this project need special mention. We relied heavily on images provided by Robin Rosetta, Lyle Buss, Tom Murray, James Solomon, Jerry A. Payne, Herbert A. (“Joe”) Pase III, David Cappaert, Susan Ellis, Johnny N. Dell, David Leatherman, Frank Peairs, John Capinera, Eric R. Day, Steven Katovich, Lorraine Grainey, and photographers, notably Jack Kelly Clark, associated with the University of California Statewide IPM Program. We express particular appreciation to Jim Kalisch and his colleagues at the University of Nebraska, who shared the UNL entomology images to help make this project a success. It has also been a pleasure to work with the professionals associated with Princeton University Press. Lucinda Treadwell provided a copyedit that identified all the flaws of the “perfect” manuscript we submitted. David PriceGoodfellow oversaw the magic that needed to be done to coherently transform the words and images (a lot in this case!) we had provided to this project. And Mark Bellis, Stephanie Rojas, and Robert Kirk helped pull it all together. Thank you. Finally, but not least, we wish to thank Sue Ballou and Renée Shetlar for their support and understanding while we had to divert a bit too much time from our families throughout the long process of developing this project.

15

CHAPTER ONE

INTRODUCTION TO GARDEN INSECTS AND THEIR RELATIVES With few exceptions, the animals covered in this book are all classified as members of the phylum Arthropoda—the arthropods. As such, all share certain physical features, including: — — — — —

division of the body into segments; an external skeleton (exoskeleton) and growth that requires periodic shedding of the exoskeleton (molting); jointed appendages; internal structures that include a heart running along the upper (dorsal) part of the body and a nerve cord running along the lower (ventral) part of the body; and symmetrical construction of both sides of the animal (bilateral symmetry).

In the manner in which all life forms are organized and classified, the primary subdivisions of a phylum, such as Arthropoda, are known as classes. Although this book concerns itself primarily with the class Insecta, the insects, representatives of six other arthropod classes may be found in yards and gardens: springtails, arachnids, millipedes, centipedes, symphylans, and some land-adapted crustaceans (e.g., sowbugs, pillbugs). There are a few additional groups of animals included in this book, notably the slugs and snails. These are mollusks, phylum Mollusca, more closely related to clams and mussels than insects, but often perceived as being “garden bugs” and may produce injuries similar to those of many insects. Two other phyla are given a bit of attention in chapter 6, the segmented worms, phylum Annelida, which includes earthworms, and the flatworms, phylum Platyhelminthes. The classification of the animals described in this book, to the order level, is summarized as follows: Phylum ARTHOPODA Arthropods Class MALACOSTRACA Order Isopoda Pillbugs and Sowbugs Order Decapoda Crayfish, Shrimp Order Amphipoda Amphipods Class DIPLOPODA Millipedes Order Julida Order Spirobolida Order Polydesmida Flat-backed millipedes Order Polyxenida Bristly millipedes Class CHILOPODA Centipedes Order Lithobiomorpha Stone centipedes Order Scolopendromorpha Bark centipedes Order Geophilomorpha Soil centipedes Order Scutigeridae House centipedes Class SYMPHYLA Symphylans Order Scutigerellidae Symphylans

Class ARACHNIDA Arachnids Order Opiliones Daddy longlegs, Harvestmen Order Araneae Spiders Order Acari Mites and Ticks Class COLLEMBOLA Springtails Class INSECTA Insects Phylum MOLLUSCA Mollusks Class GASTROPODA Gastropods Clade: Stylommatophora Slugs and Snails Phylum ANNELIDA Segmented Worms Class CLITELLATA Leeches and Earthworms Subclass Oligochaeta Earthworms Phylum PLATYHELMINTHES Flatworms, Flukes, Tapeworms Class TERBELLARIA Free-living Flatworms 16

B

A

C

D

E

F

G Representatives of the seven classes of arthropods that may be found in yard and garden: (A) grasshoppers (Insecta); (B) springtails (Collembola); (C) spiders (Arachnida); (D) garden symphylans (Symphyla); (E) centipedes (Chilopoda); (F) isopods (Malacostraca); (G) millipedes (Diplopoda). Representatives of Nonarthropods found in yards and gardens: (H) earthworms (phylum Annelida); (I) slugs (phylum Mollusca); (J) land planarians (phylum Platyhelminthes).

H

I

J

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

ARTHROPOD GROWTH AND METAMORPHOSIS Because arthropods possess an external skeleton, which confines their size, in order to grow they must periodically shed the exoskeleton, building a new, larger one at the same time. This process is called molting and all arthropods must molt repeatedly during their lifetime. As a result of this type of development, arthropod growth occurs in a series of distinct stages, each punctuated by a molting event. The term instar is used to describe each of the stages in a developing arthropod; insects typically pass through three to seven instars as they develop. The ultimate stage is the sexually mature adult. left: Cockroaches in stages of molting. The individual on the right is in the process of shedding the remnants of the previous exoskeleton. The pale color of the cockroaches to the left and right is the new exoskeleton, which has not undergone the process of hardening and darkening that makes up the final stage during molting. WHITNEY CRANSHAW below left: Life stages of a chinch bug, a type of insect with simple metamorphosis. On the top row is the egg, followed by three stages (instars) of nymphs. On the bottom row are different adult forms. JIM KALISCH, UNIVERSITY OF NEBRASKA below: Adults (winged and wingless forms) and nymphs of an aphid. WHITNEY CRANSHAW

During this growth process, arthropods will not only progressively increase in size but usually also undergo some changes in form, a process known as metamorphosis. Sometimes these changes are minor, perhaps involving small differences in body shape, coloration, or patterning. In others there can be dramatic differences in appearance during different stages in their development. Broadly speaking, among the insects, one of two general patterns of metamorphosis is followed: simple metamorphosis or complete metamorphosis. Earwigs, grasshoppers, and aphids are examples of those that have a simple type of metamorphosis. They have immature stages, known as nymphs, that generally resemble the adult in overall appearance, feed in the same manner, and occur in the same environments. In addition to a change in size, the nymphs may develop external features, such as wing pads, that become increasingly prominent in later instars. Adult insects differ from nymphs by being sexually mature and, if they are winged, having functional wings. 18

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

ARThRoPod GRowTh ANd METAMoRPhoSIS Much more specialization of function—and difference in form—occur among the insects that undergo complete metamorphosis. The immature stages are collectively known as larvae, although larvae of many insects are so recognizable that they may be referred to by a common name such as grub, caterpillar, or maggot. Immature forms are often similar in appearance, progressively increasing in size with each instar. Following is transition to a unique stage known as the pupa. Tremendous changes take place during the pupal stage as larval features disappear and transition to features unique to the adult—the transformation of a caterpillar to a butterfly being one of the best recognized examples. Among insects with complete metamorphosis, the appearance and habits of the adult may be very different from those of larvae. The overwhelming number of insect species are those that undergo complete metamorphosis and include beetles, moths and butterflies, flies, bees, ants, and wasps. Life stages of a sod webworm, a type of insect with complete metamorphosis. Stages include (left–right) egg, six stages (instars) of larvae, pupa, adult. DAVID SHETLAR

A

B

C

Life stages of a lady beetle: (A) eggs; (B) larva; (C) pupa; (D) adult.

D

WHITNEY CRANSHAW

Regardless of the type of metamorphosis, further development of external structures ceases once insects molt to their ultimate adult form. Therefore a little fly is not a “baby” big fly nor is a tiny ant a “baby” ant. They are merely adults of a small species or individuals that were stressed through poor diet or some other factor that suppressed development in their immature stages. There are variations in this development pattern among some insects and the noninsect arthropods. Springtails and insects that evolved before the development of wings, such as silverfish (order Thysanura), show little change in form as they grow, but gradually increase in size and become sexually mature in the ultimate stages. Most arachnids (spiders, mites, scorpions, and the like) have a development pattern similar to simple metamorphosis. However, among the mites and ticks, the first-instar nymphs that emerge from eggs have only six legs, obtaining their full complement of eight legs only after the next molt (second instar). Among all millipedes and many centipedes, additional leg-bearing segments will be added during some molts, resulting in a type of growth known as anamorphic development. 19

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INSECT ORDERS Several features separate insects from the other arthropod classes. These include: — — —

division of the body into three main regions (head, thorax, abdomen); three pairs of legs, located on the thorax; and one pair of antennae.

FIG.1

FIGURES BY MATT LEATHERMAN

Thorax

FIG. 2

head

figure 1. Body regions of an adult insect. figure 2. Body regions of two insect larvae.

head

Abdomen Thorax

head

Thorax

Abdomen

Abdomen

Many insects also develop wings in the adult stage and thus are the only winged arthropods. Currently, about 30 orders of insects are recognized. Several are infrequently, if ever, encountered in North American yards and gardens because of their small size, scarcity, or habits that restrict them to different environments. The orders and types of metamorphosis of the insects most likely to be seen in yards and gardens include: ORDER (COMMON NAME)

TYPE OF METAMORPHOSIS

Coleoptera (beetles)

Complete

Diptera (flies, gnats, mosquitoes, and relatives)

Complete

Lepidoptera (butterflies, moths, skippers)

Complete

Hymenoptera (ants, bees, wasps, sawflies, and

relatives)

Complete

Neuroptera (lacewings, antlions, and relatives)

Complete

Thysanoptera (thrips)

Variation on simple metamorphosis including nonfeeding stages prior to adult emergence

Odonata (damselflies and dragonflies)

Simple, but immature form lives in water and has substantial physical differences from adult form

Orthoptera (grasshoppers, crickets, katydids)

Simple

Mantodea (mantids)

Simple

Phasmatodea (walkingsticks)

Simple

Blattodea (cockroaches and termites)

Simple. The social species (termites) produce different forms/ castes (reproductive females, reproductive males, soldiers, workers). Termite workers may remain in immature form for life, but can differentiate to specialized adult forms with colony needs.

Dermaptera (earwigs)

Simple

Hemiptera (true bugs, aphids, psyllids, whiteflies, etc.)

Simple, but some species have nonfeeding stages that share features intermediate with complete metamorphosis 20

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IDENTIFICATION OF IMMATURE STAGES OF ARTHROPODS Because of the changes that occur during development, arthropods change in appearance at different life stages. These changes are particularly dramatic in insects that undergo complete metamorphosis (e.g., beetles, moths and butterflies, bees, ants, wasps, and flies). Often it is the immature stage (e.g., caterpillar, grub) that causes most plant injury, as many larvae are specialized feeding machines. Adults may feed in a very different way and have very different form and functions (e.g., reproduction, dispersal); thus, it can be particularly difficult when observing insects that have complete metamorphosis to associate the adult and immature stages as being the same species. The arthropod orders with immature stages most likely to be seen in yards and gardens are discussed below.

Coleoptera

(Beetles)

Beetle larvae are often known as grubs. All possess strong jaws designed to chew, and the jaws may be quite prominent in species that chew wood or capture prey. Three pairs of legs on the thorax are clearly present among those species that actively move about aboveground or on the surface of plants (e.g., lady beetles, leaf beetles). Grubs that develop belowground or within plants typically lose pigmentation and are pale colored, usually creamy white. Among those that actively dig in soil, such as the white grubs, the front legs are well developed and may be used in digging. Many important groups of beetles develop within plants, however, and their larvae have lost all legs in the course of evolution, leaving only the darkly colored head capsule as a conspicuous feature. The larvae of bark beetles and weevils somewhat resemble pieces of puffed rice with a dark head. Flatheaded borers, the larvae of metallic wood borers, are quite elongated and have a broad area on the first segment of the thorax. Roundheaded borers, larvae of longhorned beetles, are also quite elongated, with the dark prominent jaws distinguishing the head region.

top: Larva of a ground beetle (Coleoptera). WHITNEY CRANSHAW

above: Larva of a metallic wood borer, known as a flatheaded borer (Coleoptera). WHITNEY CRANSHAW

top: Larva of a scarab beetle, known as a white grub (Coleoptera). JIM KALISCH, UNIVERSITY OF NEBRASKA above: Larva of a leaf beetle (Coleoptera) WHITNEY CRANSHAW

21

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IdENTIFICATIoN oF IMMATuRE STAGES oF ARThRoPodS

Lepidoptera

(Butterflies, Moths, Skippers)

Immature stages of lepidopterans are known as caterpillars. They possess the normal three pairs of true legs on the thorax but, unlike most immature insects, they also possess fleshy leglike extensions, known as prolegs, on several segments of the abdomen. Each proleg is tipped with minute hooks, known as crochets, arranged in patterns characteristic of each family. All lepidopteran caterpillars can be distinguished from other insect larvae by the presence of two to five pairs of prolegs, each of which is tipped with crochets. The legs and prolegs of caterpillars that bore into plants (e.g., clearwing borers) may be very reduced; however, the presence of crochets always distinguishes them from other wood-boring larvae.

Larva of a sphinx moth (Lepidoptera).

WHITNEY CRANSHAW

Larva of a geometrid moth, known as a looper or inchworm (Lepidoptera). JIM KALISCH, UNIVERSITY OF NEBRASKA below: Illustration of the prolegs, tipped with hooks (crochets) that are present on the abdomen of Lepidoptera larvae. FIGURE BY MATT LEATHERMAN head  capsule

Underside of a caterpillar of the Zimmerman pine moth, showing the prolegs on the abdomen that are tipped with hooks (crochets). JIM KALISCH, UNIVERSITY OF NEBRASKA

prolegs

Crochets

thoracic legs

Neuroptera (Lacewings, Antlions, and Relatives) All neuropteran larvae are predators. Curved, lancelike jaws project prominently from the head. Larvae possess legs on the thorax but no prolegs on the abdomen.

Hymenoptera

(Ants, Bees, Wasps, Sawflies, and Relatives)

Larvae of a green lacewing (Neuroptera).

WHITNEY CRANSHAW

Rarely do gardeners encounter the larval stages of most insects in the order Hymenoptera. This is because they either occur within colonies (e.g., social wasps, honey bees, ants), develop in specialized nest cells (e.g., hunting wasps, leafcutter bees), or are hidden within plants (e.g., gall wasps). These larvae are usually very pale-colored and have little pigmentation except around the mouthparts. A distinct head region is present but can be difficult to distinguish since there is little difference in color to distinguish it from the rest of the body. 22

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IdENTIFICATIoN oF IMMATuRE STAGES oF ARThRoPodS far left: Larvae of sawflies (Hymenoptera). GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD. ORG

left: Adult ants tending larvae (Hymenoptera). DAVID SHETLAR

Larval features are very different among some of the active leaf-feeding larvae, notably the sawflies. Sawfly larvae look quite similar to moth and butterfly larvae and similarly are often termed caterpillars. Like Lepidoptera larvae, sawfly larvae have prolegs on the abdomen, but the number is significantly different. Sawflies possess six to eight pairs of prolegs, and none have the hooklike crochets at the tip that characterize moth and butterfly larvae.

Diptera

(Flies, Gnats, Mosquitoes, and Relatives)

Larvae of the “true flies” completely lack legs. Furthermore, many lack any distinct head area. Instead the head end is often tapered to a point and surrounds a pair of tiny hooks that are normally retracted. A pair of eyelike spiracles are commonly present on the hind end. This larval form is known as a maggot and is produced by flies in the suborder Brachycera (e.g., root maggots, house flies, flower flies). Larvae in the suborder Nematocera (e.g., gnats, midges, mosquitoes) also lack legs but have a distinctly visible head capsule that is often darker than the rest of the body.

above: Larvae of fungus gnat (Diptera), massed on lawn. left: Larva of a syrphid fly (Diptera) with colony of aphids (Hemiptera). JIM KALISCH, UNIVERSITY OF NEBRASKA

23

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IdENTIFICATIoN oF IMMATuRE STAGES oF ARThRoPodS

Orthoptera

(Grasshoppers, Crickets, Katydids)

Most features of immature and adult Orthoptera are similar. Only the adult has fully developed wings, however. Coloration and patterning among nymphs also commonly change with age. Wing pads are present on immature stages and become more prominent as maturity approaches.

above: Adult and nymph of a grasshopper (Orthoptera). WHITNEY CRANSHAW

right: Katydid nymph (Orthoptera).

JIM KALISCH, UNIVERSITY OF NEBRASKA

Dermaptera

(Earwigs)

Most features of immature and adult earwigs are similar. The forceps-like cerci on the tip of the abdomen and the wing pads increase in size as the insects mature.

Mantodea

(Mantids)

Mantids are recognized by their raptorial (grasping) front legs. Most external features of immature and adult mantids are similar except for the wings. As mantids develop, the wing pads become increasingly prominent, with the wings becoming fully developed and functional only in the adult stage.

above: Adult earwig tending young (Dermaptera). KEN GRAY COLLECTIONS, OREGON STATE UNIVERSITY

below: Nymph of a Carolina mantid (Mantodea). DAVID SHETLAR

Blattodea

(Cockroaches and

Termites) Most external features of immature and adult cockroaches are similar except for the wings. As cockroaches develop, the wing pads become increasingly prominent, with the wings becoming fully developed and functional only in the adult stage. 24

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IdENTIFICATIoN oF IMMATuRE STAGES oF ARThRoPodS Features of almost all immature and adult termites are similar, differing only in size. However, termites are social species and metamorphosis patterns are more flexible, allowing the production of various castes (e.g., workers, soldiers, reproductives) as colony needs determine. Reproductive forms possess large, functional wings in the adult stage and distinct wing buds in the early stages of development. Workers and soldiers are blind and not or only lightly pigmented. Winged reproductives have eyes and are often black or brown.

Thysanoptera

(Thrips)

Most immature thrips roughly resemble adults in general body form, and the first two nymphal instars often are found together with the adults on plants. However, immature thrips lack wings and often have different coloration. Late stages (instars 3 and 4) usually drop to the soil and undergo physical changes, such as development of wing pads, which make them progressively similar to the ultimate adult form.

Hemiptera

(True Bugs, Aphids, Psyllids, Whiteflies, Scale Insects, Cicadas, Leafhoppers, and relatives)

top: Life stages of an American cockroach (Blattodea). JIM KALISCH, UNIVERSITY OF NEBRASKA

above: Nymphs of subterranean termite (Blattodea) in different stages of development. DAVID SHETLAR

The order Hemiptera contains a large number of insects that all possess “piercing-sucking” mouthparts of similar design that allow them to pierce tissues (usually plant tissues) and suck fluids. All have a simple type of metamorphosis, and thus immature stages (nymphs) feed in a manner similar to the adults and share many other habits with them. Body form is generally similar, but nymphs lack the fully developed wings of the adults and are not sexually mature. Wing pads become increasingly prominent as the nymphs approach maturity. In some families, however, there can be unusual forms. In whiteflies and psyllids, nymphs are quite flattened and look very different from the winged adults. This is particularly true in whiteflies where there is a special nonfeeding transition stage (sometimes

above: Nymphs of an onion thrips (Thysanoptera). WHITNEY CRANSHAW

left: Adult and nymph of a potato leafhopper (Hemiptera). TED RADCLIFFE, UNIVERSITY OF MINNESOTA

25

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IdENTIFICATIoN oF IMMATuRE STAGES oF ARThRoPodS left: Nymphs of a milkweed bug (Hemiptera). DAVID SHETLAR

below left: Damselfly nymph (Odonata). TOM MURRAY

below: Dragonfly nymph (Odonata). TOM MURRAY right: Adult and immature springtail. DAVID SHETLAR below right: Larva and adult of a European red mite. DAVID SHETLAR

referred to as a pupa) immediately preceding the adult. The first stage following egg hatch among scale insects, known as the crawler, is highly mobile and little resembles the more sedentary later stages that produce a waxy cover. Similarly, the nymphs of cicadas are specialized for life belowground, whereas adults are winged and look substantially different.

Odonata

(Damselflies and Dragonflies)

Immature stages of dragonflies and damselflies develop in water and will not be encountered in a yard/garden setting, except sites with permanent water features. Their appearance is much different from their ultimate adult form, being wingless, often much more squat in body form, and possessing a unique modification of the mouthparts: an extensible “lower jaw” (labium) that is used to help capture insects and other prey. When full grown, the nymphs migrate to the edges of ponds or onto emergent vegetation, rocks, or other surfaces then molt to the adult stage.

Collembola

(Springtails)

All stages of springtails have similar external features and differ only in size. Unlike insects, springtails will continue to molt after they have reached the adult stage.

Acari

(Mites and Ticks)

Following egg hatch, all mites (except eriophyid mites) and ticks are minute and six-legged, a stage known as a larva. After the first molt they transform into eight-legged immature stages (nymphs) and possess the general body form of the adult for the remainder of their development. Among spider mites there are two additional molts as 26

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

IdENTIFICATIoN oF IMMATuRE STAGES oF ARThRoPodS they transform through the protonymph and deutonymph, ultimately reaching the adult form. Other mites may have an additional nymphal stage (tritonymph). Special inactive “resting stages” may occur with these groups of mites. An unusual mite family is the eriophyid mites. These are minute, with an elongate, carrot-shaped form, and they possess only two pairs of forward-facing legs in all life stages.

Diplopoda (Millipedes)

above: Immature julid millipede. WHITNEY CRANSHAW below: Immature stone centipede. TOM MURRAY

After egg hatch, the first instar of a millipede usually remains where the eggs were laid, and many have only three pairs of legs at this time. Subsequently, as they develop, millipedes go through many molting episodes, and during the early instars, they will add segments (with pairs of legs) following a molt. In addition to having more body segments and legs, older millipedes tend to darken in color.

Chilopoda (Centipedes) Stone centipedes (order Lithobiomorpha) and house centipedes (order Scutigeromorpha) emerging from eggs (first instar) possess as few as 14 legs but add pairs in the next instars until they possess their full complement of 30 legs (15 pairs). Soil centipedes (order Geophilomorpha) and bark centipedes (order Scolopendromorpha) have their full complement of legs and segments at birth.

Terrestrial Isopods

(Pillbugs and Sowbugs)

Adult pillbugs and sowbugs retain their eggs in a body pouch (marsupium). After the eggs hatch the immature forms disperse and within the first day they molt, at which time they gain an additional segment in the thoracic area. A couple of weeks later a second molt occurs and the seventh pair of legs develop. After this point they will periodically molt to larger sizes but have the same body form. Unlike other arthropods found in yards and gardens, pillbugs and sowbugs molt in two events each time, first shedding the exoskeleton of the back half, followed by that of the front.

far left: Adult and immature pillbugs. WHITNEY CRANSHAW

left: Sowbug in process of molting. TOM MURRAY

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EXCRETED AND SECRETED PRODUCTS USEFUL IN DIAGNOSING GARDEN ARTHROPODS AND SLUGS HONEYDEW This is a sticky, largely sugary liquid excreted by certain insects that feed on the phloem of plants. It is produced by certain insects in the order Hemiptera, notably aphids, soft scales, whiteflies, mealybugs, and some leafhoppers. Because of its high sugar content, honeydew is highly attractive to ants, wasps, bees, flies, and other insects. On surfaces where honeydew persists for long periods, it supports the growth of sooty molds, darkcolored fungi that may be seen on leaves, branches, and soil surfaces under plants that are supporting high populations of a honeydew-producing insect. far left: Honeydew being excreted by soft scales. WHITNEY CRANSHAW

left: Droplets of honeydew on a leaf. DAVID SHETLAR below left: Sooty mold growing on a leaf surface that was covered with honeydew. DAVID SHETLAR

below: Tar spot excrement produced by lace bugs. WHITNEY CRANSHAW

TAR SPOTS Dark fecal spots on foliage are associated with many plant-feeding insects that suck sap from the mesophyll (leaf tissues) of plants. These include thrips, lace bugs, some leafhoppers, plant bugs, and spider mites. Because of the nature of the feeding, there is usually associated leaf spotting (white, yellow, or brown spots). The size of the tar spots is related to the size of the insects. Spotting is also produced by most moths shortly after they emerge from the pupal stage. It is usually pale brown or reddish brown and is known as meconium. Syrphid flies, a common family of aphid predators, also leave dark smears of excrement on plants.

above: Excrement (frass) produced by a grasshopper.

FRASS The solid excrement produced by insects that WHITNEY CRANSHAW feed on solid foods is known as frass. Texture and right: Excrement (frass) consistency depend largely on diet; insects feeding on produced by cabbageworms. WHITNEY CRANSHAW high-moisture foods produce soft and watery frass, whereas those feeding on dried wood or grain produce granular frass. In some species the frass may have a highly characteristic pattern or texture and can be a useful identification aid. 28

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EXCRETEd ANd SECRETEd PRoduCTS SILK The silk found around plants is most characteristic of caterpillars such as leafrollers, tent caterpillars, and webworms that use silk to create shelters and tie foliage together. The webspinning sawflies also construct shelters of silk. Silk, formed into a cocoon, also surrounds the pupal stage of many moth larvae, sawflies, lacewings, and other insects. Most spider mites produce visible silk, particularly when their populations are high. Spiders use silk for many purposes. Most obvious are the webs some species use to snare prey. Other spiders use silk to form a “retreat” in which they hide when not foraging for prey. Also, almost all spiders use silk to cover egg masses.

above left: Silk producing a cocoon that covers the pupae of a parasitoid wasp. WHITNEY CRANSHAW above: Silk being used by spider to bind prey. WHITNEY CRANSHAW top right: Silk used as a shelter for a leaf-feeding caterpillar. JIM KALISCH, UNIVERSITY OF NEBRASKA

bottom right: Silk used to cover spider egg mass. The top cover of silk has been peeled away in this image. WHITNEY CRANSHAW

above left: Wax covering bodies of planthoppers. DAVID SHETLAR above right: Wax pellets excreted by potato/tomato psyllid. WHITNEY CRANSHAW below: Mucous “slime trails” produced by a slug. DAVID SHETLAR

WAX Many bees secrete wax from specialized glands to line or form cells used to rear young and store fluids. On plants, waxy material may be present as excreted products of some sap-feeding insects, particularly psyllids. This excreta may take the form of small pellets or waxy threads. Wax may be secreted to cover the body of the “woolly” aphids, mealybugs, planthoppers, some scale insects, and psyllids. It can often be quite conspicuous when produced as egg sacs by mealybugs and soft scales. MUCOUS TRAILS Slugs and snails produce a mucous covering that appears as a “slime trail” on surfaces they contact. It disappears rapidly with drying and is best observed early in the morning or in humid sites. 29

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BODY PARTS USEFUL IN DIAGNOSING GARDEN ARTHROPODS EXUVIAE (CAST SKINS) All arthropods shed their exoskeleton several times in the process of developing. Insects with chewing mouthparts usually consume the remnants of the cast-off exoskeleton (exuviae), shortly after molting. Insects with sucking mouthparts, such as aphids, leafhoppers or plant bugs, and spider mites, cannot consume the old cast skin, which may subsequently persist and be useful as a diagnostic sign. SCALE COVER The waxy cover of a scale insect is a shield that incorporates first- and secondinstar exuviae; it is usually distinctive enough in shape and coloration to distinguish species.

above: Spider mites and discarded exuviae. WHITNEY CRANSHAW right: Grasshopper in the process of molting, leaving behind remnants of the old exoskeleton (exuviae). WHITNEY CRANSHAW

far left: Covers of an oystershell scale insect. DAVID SHETLAR left: Covers of San Jose scales on apple fruit. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Furthermore, a scale covering may persist on a plant for a long time after the insect underneath has died, ultimately weathering and flaking off. The scale cover can also identify the stage of the insect, as the covering often appears as a series of rings, each produced following a molt. EGGSHELLS Following egg hatch, many insects with chewing mouthparts consume the discarded eggshells. However, spider mites and insects with mouthparts designed to suck fluids leave the old eggshells intact. These may persist on foliage for a considerable period. Even when the insects or spider mites are no longer present, the old eggshells can be useful for diagnosis.

Spider mites and eggs. After egg hatch the eggshells remain intact. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY 30

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COMMON TYPES OF PLANT INJURIES CAUSED BY INSECTS BRONZING/RUSSETING A generalized bronzing or graying of leaf and needle surfaces results from sustained feeding by large numbers of spider mites or rust mites. Such bronzing can start out as white or yellow stippling (see below) that turns brown with age. Often there is an associated thickening or increased leatheriness of the leaf or fruit surface. When such injury occurs on fruit, it is often termed russeting, and affected fruit may also show some slight scarring. CATFACING OF FRUIT Distortion of the normal shape of fruit can result from a wide range of injuries to young fruit. Insects with sucking mouthparts, notably plant bugs and stink bugs, kill areas around the feeding site, resulting in deep dimples as the fruit expands. Smaller dimpling may result from egg-laying wounds or chewing injuries of adult weevils. Surface feeding on expanding fruit by caterpillars (fruitworms, leafrollers) typically results in large sunken areas, often with a scabby texture. Collectively these types of fruit distortions induced by insects are known as catfacing injuries.

Catfacing injury of apple produced by plant bug feeding on young fruit. WHITNEY CRANSHAW

Leaf bronzing produced by rust mites on baldcypress. LORRAINE GRANEY, BARTLETT TREE EXPERTS, BUGWOOD.ORG

Russeting of citrus fruit by citrus rust mite. DON FERRIN, LOUISIANA STATE UNIVERSITY AGRICULTURAL CENTER, BUGWOOD.ORG

Defoliation of cabbage by imported cabbageworms. WHITNEY CRANSHAW

DEFOLIATION Strictly, defoliation relates to any leaf loss; however, it can be effected in many different ways. Most commonly it is caused by chewing insects that remove sections of tissue from individual leaves. Entire leaves may be consumed in this manner or leaves may subsequently drop (abscise) in response to injury. Defoliating insects that chew leaves include caterpillars, adults and larvae of many beetles, sawfly larvae, grasshoppers, earwigs, and leafcutting ants. Some insects defoliate plants in a characteristic manner and produce injuries described in such terms as notching, shotholing, skeletonizing, and windowpaning. Leaves may also drop prematurely in response to various stresses including drought and nutrient deficiencies. High populations of spider mites and sap-sucking insects (aphids, leafhoppers, scales) may also induce premature leaf drop. 31

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CoMMoN T YPES oF PLANT INJuRIES CAuSEd BY INSECTS FLAGGING Wilting of leaves that remain attached results when water movement has been prevented from reaching the leaf tissues. This can be caused by various pathogens that girdle twigs, such as fire blight, or those that restrict water movement by plugging the xylem, such as Dutch elm disease. However, many insects can produce flagging by chewing twigs. Twig girdlers, certain grasshoppers, and European hornets are examples of insects that may chew on the outside of bark. Tip moths cause dieback of twigs, and other twig-boring caterpillars cause similar injuries to deciduous trees and shrubs. Flagging may occur on just the terminal growth of conifers, as occurs with white pine weevil. A less common cause of flagging is wounding produced during egg-laying. These oviposition injuries are most prominent with cicadas, whose wounds often cause twigs to break. right: Twig flagging of plum due to tunneling by larva of peach twig borer. ROBIN ROSETTA, OREGON STATE UNIVERSITY

far right: Flagging of terminal growth of spruce due to injury by white pine weevil. WHITNEY CRANSHAW below: Open form gall produced by a gall midge. DAVID SHETLAR

bottom: Closed galls, produced by a gall wasp. DAVID SHETLAR

GALL PRODUCTION Many insects, mites, and some plant pathogens can cause plants to produce abnormal plant growths known as galls. Galls can occur on leaves, stems, flowers, branches, and roots of plants and are often of distinctive form. Insect- and mite-induced galls are generally called open or closed galls. Open galls are formed by insects with sucking mouthparts, gall midges, and mites. Such galls have a natural opening that has the edges tightly held together until the insects or mites finish their development. At this time, the tissues shrink back and provide an opening for the insects or mites to escape. Closed galls completely surround the developing insect. These are formed by larvae of beetles, caterpillars, and wasps that have chewing mouthparts as larvae or adults, allowing them to chew a hole through the gall tissues allowing escape. LEAF CUPPING AND CURLING Leaves may cup in response to removal of tissue or to feeding by sucking insects during leaf expansion. This symptom is most characteristic of feeding injuries produced by certain thrips, 32

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

CoMMoN T YPES oF PLANT INJuRIES CAuSEd BY INSECTS

left: Leaf curling produced by honeylocust plant bugs feeding on emergent leaves. WHITNEY CRANSHAW above: Leaf curls produced by aphids. WHITNEY CRANSHAW above right: Leaf curls produced by Cuban laurel thrips. DAVID SHETLAR

plant bugs, aphids, and psyllids. (Other causes of leaf cupping include exposure to some herbicides and cold injury.) Feeding by some insects, notably aphids, can cause new leaves to tightly curl. LEAF FOLDING, ROLLING, AND TYING Several species of caterpillars fold over the margins of leaves and feed from within the fold. Affected leaves are held shut by tabs of silk. There are also many species of caterpillars that roll up leaves and feed within the protection of these shelters. Additional species of caterpillars tie two leaves together with silk and feed between the two layers.

above: Hydrangea leaftier larva exposed from shelter of tied terminal leaves. DAVID SHETLAR right: Grape leaffolder larvae exposed in shelter produced by rolled leaf edge. DAVID SHETLAR far right: Two oak leaves tied together to form shelter for a leaftying caterpillar of oak. DAVID SHETLAR

MINING OF LEAVES AND NEEDLES Certain insects, known as leafminers and needleminers, develop by tunneling between the upper and lower surfaces of leaves and needles, respectively. External evidence of these insects appears as discolored tunnels, often in a blotch or serpentine form. Leafminers can be separated from other 33

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

CoMMoN T YPES oF PLANT INJuRIES CAuSEd BY INSECTS

Serpentine-form leafmines. JIM KALISCH, UNIVERSITY OF NEBRASKA

Blotch-form leafmines produced by elm leafminer larvae.

Larvae of a needleminer in ponderosa pine needles.

WHITNEY CRANSHAW

ROBERT STEVENS, USDA FOREST SERVICE

causes of leaf spotting (e.g., fungi, bacteria, chemical injuries) by the leaf surfaces being easily separated and by the presence of the larvae and/or excrement. Leaf- and needleminers include larvae of various caterpillars, sawflies, flies, and beetles. NOTCHING OF LEAF MARGINS Chewing along the edge of leaves is characteristic of many insects such as certain adult weevils, caterpillars, sawflies, earwigs, and grasshoppers. Only a few limit feeding to the margin, however, and some make regular, angular cuts, which is particularly common among adult root weevils, such as the black vine weevil. Notching is also used to describe the semicircular cuts characteristic of leafcutter bees and leafcutting ants.

Angular leaf notching produced by root weevils.

Smooth, semicircular leaf-edge cuts made by leafcutter bees. WHITNEY CRANSHAW

WHITNEY CRANSHAW

OVIPOSITION WOUNDING Some insects damage plants in the process of laying eggs (oviposition). Small puncture wounds in leaves or needles are characteristic of sawflies. Adult leafmining flies also puncture leaves both when laying eggs and to feed on fluids produced by these wounds. Less conspicuously, eggs are inserted into leaf tissues by several other insects such as leafhoppers, plant bugs, lace bugs, and thrips. 34

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

CoMMoN T YPES oF PLANT INJuRIES CAuSEd BY INSECTS

Wounds produced by cicada while inserting eggs. DAVID SHETLAR

Egg-laying scars also occur on other parts of the plant. Twig scars are produced when cicadas, treehoppers, and certain leafhoppers insert eggs into young twigs. Seriously damaged twigs may break, producing flagging. Fruit may be damaged when flower thrips or fruit flies insert eggs into developing fruit or when weevils chew the fruit surface prior to egg-laying. PANSY SPOTTING Diffuse cloudy areas on the surface of maturing fruit or leaves can result from feeding injuries by stink bugs feeding on maturing fruit. Areas around egg punctures of thrips can also result in halo-shaped pansy spots on seedpods and fruit surfaces. REDDENING Leaf reddening can be a plant response to saliva introduced by certain aphids, scales, and spider mites. This reaction is often plant specific; i.e., it can occur on some species or cultivars but not on others. Color changes can also occur in evergreens when branches die from injuries produced by bark beetles. For example, certain bark beetles that attack conifers can cause foliage to turn reddish brown. The process of color change from the original green is often called “fading.”

above: Leaf flagging resulting from twigs breaking from oviposition wounds of cicadas. DAVID SHETLAR

left: Dark scar from egg laying by thrips surrounded by pale area (pansy spotting). WHITNEY CRANSHAW

far left: Red color change induced by feeding of currant aphid. WHITNEY CRANSHAW

left: Red area developing around feeding site of rudbeckia psyllid. DAVID SHETLAR 35

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

CoMMoN T YPES oF PLANT INJuRIES CAuSEd BY INSECTS SCARRING Scarring of leaves and flowers can result from the reaction of a plant to feeding by many insects that suck sap from the mesophyll and destroy cells as they feed. Scarring injuries are most commonly associated with thrips and typically appear silvery, often with small droplets of dark feces. Scarring injuries to emergent growth often result in tattered and distorted foliage. SHOTHOLING Shothole injuries are small, generally round holes cut into leaves. One leaf surface is usually left intact, but it typically dries, allowing a hole to form through the leaf. Insects that produce shotholes include adult flea beetles, young stages of some caterpillars, and some young sawfly larvae. Large holes are typical of feeding by some adult leaf beetles and older sawflies.

above left: Leaf scars produced by thrips. WHITNEY CRANSHAW above right: Leaf tattering resulting from thrips scarring wounds made while feeding on emergent leaves. RONALD S. KELLEY, VERMONT DEPARTMENT OF FORESTS, PARKS AND RECREATION, BUGWOOD.ORG

left: Petal scars resulting from feeding injuries of thrips. WHITNEY CRANSHAW below left: Shotholes produced by a flea beetle. DAVID SHETLAR

below right: Shotholes produced by young larva of a sawfly. JIM KALISCH, UNIVERSITY OF NEBRASKA

36

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

CoMMoN T YPES oF PLANT INJuRIES CAuSEd BY INSECTS Leaf tissues may drop out in response to the puncture wounds some insects make when laying eggs. Damage of tissues by plant-bug feeding sometimes results in irregular areas that later die and drop. Some fungi also cause shotholes to form on foliage in areas where infected tissue drops out. The term shothole is also applied to exit holes produced by various small wood-boring bark beetles and weevils. SKELETONIZING This involves a pattern of selective feeding on leaves in which chewing insects avoid main veins and usually one leaf surface. This kind of injury is characteristic of insects such as Japanese beetle, larvae of certain leaf beetles, slug sawflies, and caterpillars known as skeletonizers. This feeding habit may be restricted to younger stages of caterpillars that later feed more generally on plants. The leaf surface that is skeletonized (upper vs. lower) can also be characteristic of an insect’s feeding habit.

above left: Virginia creeper leaves skeletonized by Japanese beetles.

right: Stippling injuries produced by spider mites.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

above right: Slug sawflies skeletonizing leaf surface of oak. DAVID SHETLAR

below right: Stippling injuries produced by rose leafhopper. WHITNEY CRANSHAW

STIPPLING Whitish or yellowish spots, known as stippling, are produced when insects or mites remove cell sap from leaves. Mesophyll-feeding insects such as certain leafhoppers, plant bugs, and lace bugs characteristically produce very visible stippling. The affected leaf surface can differ between species, and often there is some associated dark fecal spotting around the injury. Smaller wounds result from feeding by thrips and spider mites. When damage is extensive, injuries may coalesce to produce silvery patches or a bronzing color change on the leaves. Stippling is also used to describe the small punctures produced by some insects with their ovipositor. Many types of flies in particular 37

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

CoMMoN T YPES oF PLANT INJuRIES CAuSEd BY INSECTS use their ovipositor not only to insert eggs but also to puncture plant cells so fluids will be released, on which the flies feed. This type of injury may result in small sunken areas. STREAKING A change in color (yellow, red, white) in a streak pattern on leaves and/or stems can result from feeding by some aphids, scales, and mealybugs, particularly those that develop on grasses or other plants with parallel leaf veins. WINDOWPANING This injury is associated with chewing insects that leave a surface (usually the upper surface) of foliage intact, producing a translucent hole covered by a thin fill of leaf epidermis. Windowpaning is typical of many kinds of young caterpillars; some slug sawflies also produce it. This type of injury intergrades with shotholing (see above).

above: Streaking symptoms of leaves resulting from injury by Russian wheat aphid. JIM KALISCH, UNIVERSITY OF NEBRASKA

right: Windowpaning symptom produced by a young cabbageworm larva. WHITNEY CRANSHAW

YELLOWING Yellowing (chlorosis) is a generalized plant response to a wide variety of stresses, including nutrient deficiencies, drought, and infection by certain pathogens. It can also be induced by heavy infestations of certain sap-sucking insects such as aphids, soft scales, and psyllids. Yellowing may also result from feeding by spider mites and eriophyid mites (rust mites).

above: Premature yellowing of elm branches heavily infested with European elm scale. WHITNEY CRANSHAW above right: Yellow leaf spotting produced by feeding injury of euonymus scale. DAVID SHETLAR right: Leaf yellowing of tomato resulting from effects of potato/tomato psyllid feeding. WHITNEY CRANSHAW 38

INTRoduCTIoN To GARdEN INSECTS ANd ThEIR REL ATIvES 

PLANT PATHOGENS TRANSMITTED BY INSECTS AND MITES Many arthropods, particularly insects and some eriophyid mites, are involved in spreading plant diseases, especially those species that act as vectors, providing the sole means of disease spread. Other species may have a more casual relationship with the pathogen, moving it around as an external contaminant. In a few cases the relationship between the plant pathogen and its arthropod vector benefits the arthropod, a situation known as a mutualistic relationship. (Certain bark beetles and horntails have mutualistic relationships with plant pathogenic fungi.) Some of the plant diseases that most often involve pathogen transmission by arthropods in North America are given. PLANT DISEASE

ARTHROPOD GROUP

VIRUSES Many viral diseases of various classes, including cucumber mosaic, potato virus Y, potato leafroll

Aphids

Beet curly top

Leafhoppers

Lettuce infectious yellows, tomato yellow leaf curl, many geminiviruses

Whiteflies

Tomato spotted wilt, impatiens necrotic spot, iris yellow spot (tospoviruses)

Thrips

Wheat streak mosaic, peach mosaic, rose rosette

Eriophyid mites

PHYTOPLASMAS Aster yellows, ash yellows, elm phloem necrosis

Leafhoppers

Pear decline

Psyllids

XYLEM-LIMITED BACTERIA Pierce’s disease of grape, bacterial leaf scorch

Leafhoppers (sharpshooters)

OTHER BACTERIA Citrus greening, zebra chip

Psyllids

Various soft-rotting bacteria

Root maggots

Bacterial wilt of cucurbits, Stewart’s wilt of corn

Leaf beetles

Cucurbit yellow vine disease

Squash bug

Many bacteria, as external contaminants

Vinegar flies

FUNGI Dutch elm disease, blue stain of conifers, thousand cankers, many others

Bark beetles

Ambrosia fungi, laurel wilt

Ambrosia beetles

White rots

Horntails

Oak wilt; many other fungi, as external contaminants

Sap beetles

Many fungi, as external contaminants

Vinegar flies

Many root-rotting fungi, as external contaminants

Bulb mites

Many root-rotting fungi, as external contaminants

Fungus gnats

NEMATODES Pine wilt

Longhorned beetles (pine sawyers) 39

CHAPTER T WO

INSECTS THAT CHEW ON LEAVES AND NEEDLES

Insects in eight orders (Lepidoptera, Coleoptera, Hymenoptera, Diptera, Orthoptera, Dermaptera, Phas­ matodea, Blattodea) along with slugs and snails chew leaves of plants. Most are generalist defoliators, chewing foliage in patterns that are not particularly distinctive. Others create distinctive injuries as they feed, and these can be useful for identifying the insect associated with them. For example, some insects chew small holes in the interior of the leaves, a damage known as shothole or pit feeding. Angular leaf notching, confined along the edge of the leaf of specific plants, can be a very characteristic injury pattern produced by the adults of many weevils, particularly the “root weevils.” Smooth cuts along the edges of leaves are produced by other insects for production of shelters (e.g., waterlily leafcutter), to construct nest cells for rearing young (e.g., leafcutter bees), or as a base material to culture fungi on which they feed (e.g., leafcutter ants). Some avoid the larger veins as they feed, producing skeletonizing injury patterns. Caterpillars of several moths may skeletonize plants, particularly in younger instars. Larvae of some leaf beetles and the Mexican bean beetle skeletonize leaves, as do the slug sawflies. Skeletonizing by adult insects is much less common, but is very characteristic of the Japanese beetle. Skeletonizing of leaves can be very fine (all veins and cross veins remain) or coarse (only the largest veins remain and both leaf surfaces are consumed). Fine skeletonizers may feed only on the upper or lower leaf surface, which can be helpful in diagnosis. Other leaf­chewing insects may be identifiable by structures they produce to cover their bodies or shelter them at feeding sites. Some construct bags or cases of silk that may be camouflaged with plant parts or fecal pellets (bagworms and some casebearers). Others use leaves—rolled up (leafrollers), folded over (leaffolders), or several leaves tied together (leaftiers and webworms). Still others cut out pieces of leaves that are folded or tied together in such a way as to make a case that is carried around, or they may make tiny cases of silk or excrement (casemakers or casebearers). Finally, several caterpillars and sawflies produce silk to make dense centralized tents in the crotches of branches for resting and shelter (e.g., tent caterpillars) or to create extensive silken shelters that web over the foliage on which they are feeding (e.g., webworms). 40

A D

B

C

E

A, B. Grasshoppers (A) and Colorado potato beetles (B) are generalist

defoliators.

WHITNEY CRANSHAW

c. Flea beetle adults chew small

pits in leaves, producing shothole wounds. JIM KALISCH, UNIVERSITY OF NEBRASKA

d. Angular notching along the

leaf edge is often produced by adult weevils. WHITNEY CRANSHAW

e. A smooth, semicircular cut

F

along the leaf edge is characteristic of leafcutter bees.

G

DAVID SHETLAR

f. Mexican bean beetle larvae

avoid all the larger veins while they feed producing leaf skeletonizing symptoms. WHITNEY CRANSHAW

g. Viburnum leaf beetles

produce an irregular skeletonizing of leaves, feeding on many of the smaller veins. DAVID SHETLAR

H. A grape leaffolder, exposed

H from its leaf fold shelter. DAVID SHETLAR

I. Symptoms produced by a leafroller caterpillar on oak. DAVID SHETLAR

J. Several caterpillars of mimosa

webworm typically feed together and construct a small shelter of webbing and leaves. DAVID SHETLAR

K. Tent caterpillars construct

large silken structures in the crotches of trees and shrubs. JIM KALISCH, UNIVERSITY OF NEBRASKA

I

J

K

Insects that chew on Leaves and needLes

GRASSHOPPERS Grasshoppers are some of the most familiar of all insects, and more than 550 species occur in North America. Only a small number regularly damage gardens and almost all of these are in the genus Melanoplus.1 Species particularly injurious to plants include: — — — — —

Twostriped Grasshopper (Melanoplus bivittatus) Differential Grasshopper (M. differentialis) Migratory Grasshopper (M. sanguinipes) Redlegged Grasshopper (M. femurrubrum) Devastating Grasshopper (M. devastator)

hosts Although many types of grasshoppers particularly favor grasses, others feed preferentially on broadleaf plants or a mixture of grasses and broadleafs. Although almost all garden plants can be damaged, beans, leafy vegetables, iris, and corn are among the plants more commonly injured by grasshoppers. Damage Grasshoppers damage plants by chewing. Most feeding occurs on foliage, although immature pods and fruit may also be eaten. Bark from twigs is sometimes gnawed, causing girdling wounds that can produce dieback of branches. Distribution Redlegged grasshopper is found throughout the U.S. and southern Canada but is most common in the upper Midwest. Migratory grasshopper has an almost equally broad range but is absent in extreme southern Texas and Florida. Twostriped grasshopper is found everywhere except the Deep South. Differential grasshopper is present throughout the U.S. except in the extreme northeast, southeast, and northwest. It is most abundant between the Rocky Mountains and Mississippi River. Devastating grasshopper is confined to the Pacific States. Appearance The largest grasshoppers in this group are the differential and twostriped grasshoppers, with some adults more than 1½ inches long. A dark herringbone pattern on the hind femur characterizes differential grasshopper, although very dark forms are also sometimes produced. Two pale yellow stripes run along the back of the thorax and wings of twostriped grasshopper. Redlegged grasshoppers range from ¾ to 1 inch long with a bright yellow underside and red tibia on the hind leg. Migratory grasshopper is also medium sized, with a blue­green or reddish hind tibia. Life History and Habits As a generalized life history, Melanoplus grasshoppers spend the winter as eggs, in elongate egg pods containing 20–120 eggs inserted shallowly in soil. The eggs hatch in mid­ to late spring, depending on temperature, location of the eggs, and species characteristics. Twostriped grasshopper is a very early hatching species, as some embryonic development occurs the previous season. Egg hatch of migratory grasshopper typically follows about 2–3 weeks later, and differential grasshopper eggs often hatch shortly after this. Redlegged grasshopper eggs hatch in late spring or early summer. In all four species, the period of egg hatch can extend over a considerable period if eggs are laid in scattered sites, or hatch may occur over a short period. Development of the nymphs typically takes 5–7 weeks, during which time they pass through five or six nymphal instars. Females feed for about 2 weeks before laying eggs. Eggs are laid as pods, often containing 50 or more eggs, and several pods may be produced. Each species has preferences as to where it lays eggs, with some preferring sun­ exposed sites with compacted soil. Egg pods are typically inserted into the soil, often around the crown area or roots of plants. 42

A

B A. Twostriped grasshopper feeding on sunflower. WHITNEY CRANSHAW

C

B. Pair of differential

grasshoppers.

D

WHITNEY CRANSHAW

C. Migratory grasshopper. SCOTT SCHELL, UNIVERSITY OF WYOMING

D. Redlegged grasshopper. JIM KALISCH, UNIVERSITY OF NEBRASKA

e. Grasshopper egg pod. DAVID L. KEITH, UNIVERSITY OF NEBRASKA

F. Clearwinged grasshopper. WHITNEY CRANSHAW

G. Devastating grasshopper. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM.

H. Grasshopper laying eggs. COLORADO STATE UNIVERSITY ARCHIVES.

e

F G H

Insects that chew on Leaves and needLes

GRasshoPPeRs Grasshoppers can show migratory behaviors. Nymphs sometimes march considerable distances in bands during outbreaks. Adults are capable of flight and may fly for several miles, often at elevations of several hundred feet above the ground. Modest physical changes may sometimes occur in populations that become more migratory. For example, thinner body size and longer wings are produced by twostriped and migratory grasshoppers that go into the more migratory phase. Although grasshoppers in the genus Melanoplus are usually the species involved in damage to garden plants, there are some other species that can be regionally damaging or attract attention. Clearwinged grasshopper (Camnula pellucida)1 has had several historical outbreaks in the Rocky Mountain/High Plains region. It is a fairly common species, found in most of North America except the southeastern states. Adults are medium­sized and yellow to brown with mottled forewings and transparent hindwings. Grasses are favored, and the species can be a severe pest of small grains, but it occasionally damages onions, lettuce, cabbage, and peas in gardens. Clearwinged grasshopper eggs hatch quite early in the season, following a few warm days in early spring, and most eggs hatch over a brief period. During the summer, when eggs are being laid, the females alternately move from feeding sites in fields to egg­laying beds where soil conditions are favorable. Valley grasshopper (Oedaleonotus enigma)1 is found in semiarid areas of western North America, and is most commonly noted to be damaging in California. Eggs hatch in spring, often in early April in California, and they feed primarily on broadleaf plants, including shrubs. Both long­winged and short­winged (brachypterous) adult forms may be produced, with high temperatures favoring the latter. Carolina grasshopper (Dissosteira carolina)1 is a common, large grasshopper sometimes seen hovering over areas of bare ground. The hindwings, exposed in flight, are colorfully marked with black and have a yellow border; however, the overall color of the grasshopper, and of the covering forewings, is tannish to gray brown. Carolina grasshopper feeds on a wide variety of plants but is rarely abundant enough to cause serious damage. Eastern lubber grasshopper (Romalea guttata)2 is the largest grasshopper found in North America. Heavy­bodied and reaching a length of 2 to almost 3 inches, it is a colorful insect of variable patterning, primarily black in young stages with more yellow and orange in the adults. The short, nonfunctioning wings are pinkish or reddish. Eastern lubber is found in the southeastern states, from South Carolina to east Texas. It is most abundant in slightly moist habitats where it feeds on a wide range of weedy plants, but it does occasionally invade vegetable and flower gardens. Eggs hatch in March and April. In much of the High Plains and southern Rocky Mountain region, the plains lubber (Brachystola magna)2 is present and rivals eastern lubber in size. It feeds primarily on wild sunflower, kochia, hoary vervain, and other rangeland plants, rarely damaging cultivated plants. This species is usually green to brown and also has short wings. 1

 Orthoptera: Acrididae; 2 Orthoptera: Romaleidae

44

A. Carolina grasshopper. WHITNEY CRANSHAW

B. Eastern lubber grasshoppers feeding on crinum lilies. DOUG CALDWELL, UNIVERSITY OF FLORIDA

C. Eastern lubber grasshopper. DAVID SHETLAR

A

D. Pair of plains lubber grasshoppers. WHITNEY CRANSHAW

B

C D

Insects that chew on Leaves and needLes

FIELD CRICKETS

(Gryllus spp.)1

Damage Field crickets eat a wide variety of plant materials. Although rarely damaging to garden plants, they are occasionally associated with injury to seedlings of many plants, including tomatoes and beans. Field crickets are also one of the insects most commonly associated with damage to irrigation tubing. Occasionally field crickets will incidentally enter homes, where their persistent chirping may be considered annoying; chewing damage to fabrics by field cricket has also been reported. Distribution Field crickets are found throughout North America, with 16 species. It is difficult to distinguish most species by physical features; some often separated only by aspects of behavior, including their life cycle and the male’s song. Fall field cricket G. pennsylvanicus)1 and spring field cricket (G. veletis) tend to predominate in most of North America. Southeastern field cricket (G.  rubens), also known as the “eastern trilling cricket,” is restricted to the southeastern states. It is physically identical to texas field cricket (G. texensis) which occurs in Texas, Oklahoma, and southern states, sometimes in spectacular swarms attracted to lights. Appearance Field crickets are predominantly black, often shiny, but may have some brown on the front wing. When fully grown they are about ¾ inch long. Males and females can be easily separated by the presence or absence of the prominent ovipositor, used by the females to lay eggs. Field crickets are also well known among the “singing” insects, producing the familiar trilling chirping noises of the night. Only the males sing, which they do by rubbing special ridged structures (file, scraper) along the edge of the wings. Different songs are used to attract mates, during courtship, and to defend territories from other males. Life History and Habits Field crickets are active at ground level, usually resting under sheltering debris during the day and active at night. Overwintering stages may vary; fall field cricket spends winter as eggs in soil, spring field cricket as nearly full­grown nymphs. Eggs are laid in small groups in slightly damp soil. After egg hatch, nymphs take 2–3 months to develop, during which time they molt eight or nine times. Most field crickets have a single generation per year, but the southeastern and the Texas field cricket have two.

Other Crickets and Katydids The robust ground crickets (Allonemobius spp.)1 are a complex of six closely related species distinguishable largely by differences in song, habitat, and minor morphological features. All are varying shades of brown and can be distinguished from field crickets by having long spurs on the hind leg. They are most abundant in grassy areas, including turfgrass areas. Robust field crickets are omnivorous, feeding on dead plant material and fungi, but mostly various low­growing plants, with legumes such as clover and alfalfa preferred. The striped ground cricket (A. fasciatus) has the widest range, occurring over much of eastern North America, into Canada and the Pacific Northwest. The southern ground cricket (A. socius) is often the most common species in southern states. These crickets can be common in and around yards and fields, but they rarely damage garden plants. Most species have a one­year life cycle and overwinter in the egg stage; the southern ground cricket can have two generations. Tree crickets (Oecanthus spp.)1 are similar in length to field crickets but more slender­bodied and occur on aboveground areas of plants. Typical species are green or yellow­green; some have dark markings and black appendages. They are most commonly associated with trees and shrubs, particularly tree fruits and caneberries. All have one generation per year, with winter spent in the egg stage. 46

A

B

C D

A. Field cricket laying eggs. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Female field cricket. DAVID SHETLAR

C. Male field cricket. WHITNEY CRANSHAW

D. Field cricket,

late-instar nymph. WHITNEY CRANSHAW

E. Striped ground

cricket, female.

JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Striped ground

cricket, male.

JIM KALISCH, UNIVERSITY OF NEBRASKA

E

F

G H

G. Blackhorned tree cricket, female. DAVID CAPPAERT

I

H. Blackhorned tree cricket, male. DAVID CAPPAERT

I. Tree cricket at egg hatch. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J. Tree cricket oviposition wounds

in twig.

WHITNEY CRANSHAW

J

Insects that chew on Leaves and needLes

otheR cRIcKets and Kat YdIds Although tree crickets may feed on leaves, they do little damage. Plants are injured primarily during late summer when eggs are laid. Females insert eggs into stems and canes, which may result in rough calloused areas around the wound, increase susceptibility to stem breakage, and allow entry of canker­producing fungi into the plant. One of the common species one may find is the blackhorned tree cricket (O. nigricornis), easily distinguished because adults usually have black legs and dark markings on the head and pronotum. The twospotted tree cricket (Neoxabea bipunctata) is very common and is distinctive because of the tan color with two darker spots on the upper surface of the folded wings. Narrowwinged tree cricket (O. niveus) is another common species. The snowy tree cricket (O. fultoni)1 is a pale green species that occurs over a broad area of the northern U.S. and parts of southern Canada. It is particularly well known because it has been shown that it can be used to determine temperature, as a type of living thermometer., based on its rate of chirping, which varies reliably with temperature in a manner that has been quantified. The formula for determining temperature by chirping rate is known as Dolbear’s Law, after A. E. Dolbear, who first published on the phenomenon in 1897. The formula is T = 40 + N15, where T is temperature (in Fahrenheit) and N is the number of chirps in 15 seconds. Katydids 2 are substantially larger than tree crickets and have a general resemblance to grasshoppers but have much longer antennae and thin jumping hind legs. Most are green, which allows them to blend in well with the foliage of trees and shrubs on which they feed. Both the nymphs and adults chew leaves, rarely causing noticeable injuries. Most katydids lay their flattened eggs along twigs and these can resemble a double row of fish scales. Katydids are far more commonly heard than seen as the males make calls during evening and night to attract mates. These sounds are produced by stridulation, in a manner similar to crickets, by rubbing special structures of the forewings (the “file” and “scraper”). Perhaps best known is the song of the true katydid (Pterophylla camellifolia),2 a loud rasping “katy­did” call. This insect is widely distributed east of the Rocky Mountains, with substantial regional variation in the types of calls it produces. Clicking calls are characteristic of the broadwinged katydid (Microcentrum rhombifolium),2 also known as the greater angle-wing katydid, a species that can be found across the U.S. and in parts of southern Canada; the related lesser angle-wing katydid, M. retinerve, is restricted to eastern North America. Bush katydids (Scudderia spp.),2 marked by narrower wings, produce various rattling calls. Bush katydids tend to be more commonly encountered in the southern U.S. in gardens where perennials, grasses, and shrubs are used. These have very brightly colored nymphs that draw attention. Camel crickets 3 are wingless crickets that possess very long antennae and have a characteristically humped body in profile. Several dozen Ceuthophilus species are native to North America, with some found in very restricted environments, notably caves. Several species can be common in and around yards and gardens—and sometimes within buildings, where they are usually found in more humid areas of the structure. Camel crickets feed at night and have very omnivorous food habits, consuming fungi, dead plant matter, carrion, and dead insects. Living plants are rarely damaged. An introduced species known as the greenhouse camel cricket (Diestrammena asynamora)3 has become widely established in much of eastern North America, and in many areas it is now the most common camel cricket found outdoors and within buildings. This species more often damages living plants and is a particular pest threat within greenhouses. 1

Orthoptera: Gryllidae; 2 Orthoptera: Tettigoniidae; 3 Orthoptera: Rhaphidophoridae

48

A C

B A. Snowy tree cricket, female.

E. Eggs of the broadwinged katydid.

JIM KALISCH, UNIVERSITY OF NEBRASKA

WHITNEY CRANSHAW

B. Snowy tree cricket, male.

F. Broadwinged katydid nymph.

DAVID SHETLAR

WHITNEY CRANSHAW

C. “True” katydid.

G. Bush katydid, Scudderia sp.

HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

D. Broadwinged katydid. WHITNEY CRANSHAW

WHITNEY CRANSHAW

H. Greenhouse camel cricket. JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Camel cricket. DAVID SHETLAR

D

E

F

G

H

I

Insects that chew on Leaves and needLes

COMMON (NORTHERN) WALKINGSTICK (Diapheromera femorata)1

hosts Oak, black cherry, elm, basswood, and black locust are favored plants. Paper birch, aspen, dogwood, and hickory are occasional hosts. Damage Nymphs and adults chew leaves. Damage is usually minor, but occasional outbreaks in forests cause significant defoliation. Distribution Over much of the area east of the Great Plains except the most southern states. It is most numerous around the Great Lakes. Appearance Full­grown adults reach a length of about 3 inches. They are highly variable in color and may be nearly pure green, gray, brown, or mottled. Life History and Habits Eggs of the common walkingstick hatch in late spring from eggs resting on soil. In forests the young nymphs usually feed first on the leaves of low­growing plants, then move to trees as they get older. Adults are present by midsummer, and the females drop their seedlike black eggs indiscriminately until frost. In southern areas of the range, these eggs usually hatch the following spring, but in the northern states and Canada they remain dormant until the second season.

Related Species There are 29 species of walkingsticks in North America, but most are rarely observed. Twostriped walkingstick (Anisomorpha buprestoides) is one of the larger North American species, with a body length of about 2½–3 inches, and is marked with 3 longitudinal black stripes. It is found in the Gulf States, where it feeds primarily on oak, although rose, crape myrtle, and other plants are also reported hosts. For defense it can discharge a directed squirt, over a distance of 12 inches or more, of a strong smelling fluid that can be very irritating to eyes and mucous membranes. The northern twostriped walkingstick, A. ferruginea, is a related, smaller species with more northern range. The most common species in the Great Plains and Rocky Mountains States is the prairie walkingstick (D. velii), which feeds on various prairie shrubs and grasses, notably big bluestem. 1

 Phasmatodea: Heteronemiidae

50

A B

C

D

A. Walkingstick. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

B. Walkingstick. DAVID CAPPAERT

C. Prairie walkingstick, mating pair. WHITNEY CRANSHAW

D. Mating pair of Anisomorpha sp. walkingsticks. HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

51

Insects that chew on Leaves and needLes

EUROPEAN EARWIG (Forficula auricularia)1 hosts European earwig is a true omnivore and feeds on a diet of insects and plant matter. Small, soft­bodied insects such as aphids and insect eggs are important protein sources; these are supplemented with soft plant matter from leaves and flower petals, especially during dry weather. European earwig can be particularly abundant on plants that also provide tight areas for daytime shelter, such as large flowers (e.g., rose, dahlia) and the ear tips of corn. Damage Adults and nymphs may feed on leaves, flower blossoms, and corn silks. Tender vegetable seedlings may be entirely consumed and soft, ripe fruits such as peaches and nectarines may be tunneled, the earwigs usually entering through the stem end. The habit of Euopean earwig to seek out tight, dark places to spend the day can make it an unwanted presence in many types of harvested fruits, vegetables, and flowers. Distribution As the name implies, European earwig is an introduced species. It has spread rapidly and is now found throughout almost all of North America with the exception of some southern states. Appearance Adults are approximately ¾ inch long with prominent pincers. The general color is reddish brown, often with bronze tones. Short, pale brown wing covers are present on the thorax. Males have long, bowed pinchers while those of females are fairly straight. Life History and Habits European earwigs overwinter primarily as adult females. They become active on warm days in late winter, when the females dig small nests beneath rocks, within mulched areas of garden beds, or in other protected sites. A cluster of about 50 eggs is produced and then tended by the mother. After the eggs hatch, typically in late March or April, the mother continues to guard and care for the young earwigs for several weeks until they have molted and are ready to leave the nest. The young then disperse to forage on their own, becoming full grown in about 1 month. Often the mother lays a second, smaller egg mass in May or June. There is only one generation per year, but developing earwigs may be present throughout the growing season because of the double broods of overwintered females. Foraging occurs at night, with movement to dark, sheltered areas during the day. As the season progresses, the earwigs increasingly tend to aggregate in these shelter sites. Although the European earwig has wings, it very rarely, if ever, flies.

Other Earwigs Ringlegged earwig (Euborellia annulipes)2 is found primarily in warmer areas but is occasionally found throughout much of the continent. It is appears black with white bands on the legs and is wingless. Like the European earwig it has omnivorous food habits, doing some leaf chewing, but feeds primarily on other arthropods and is often an important biological control of some pest insects. Two generations are produced annually. Three species of earwigs in the genus Doru1 occur in the southern U.S. They have wings and are marked with tan bands on the area behind the head (pronotum) and front wings. They are predators of caterpillars and other insects. Shore earwig (Labidura riparia)3 is the largest earwig found in the southern U.S. and Mexico, most commonly in coastal areas. It is also a predator but will occasionally throw up mounds of soil in gardens and low­ cut turf. Adults can effectively apply a noticeable pinch with their cerci.  Dermaptera: Forficulidae; 2 Dermaptera: Carcinophoridae; 3 Dermaptera: Labiduridae

1

52

B C

A D

A. European earwigs resting in leaf fold. DAVID SHETLAR

B. Female (top) and male (bottom) European earwigs. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. European earwig female tending

eggs.

DAVID SHETLAR

E

D. Immature European earwig. WHITNEY CRANSHAW

E. European earwig feeding at night. WHITNEY CRANSHAW

F. Ringlegged earwig. DAVID SHETLAR

G. Doru sp. earwig. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

H. Shore earwig. DAVID SHETLAR

F

G H

Insects that chew on Leaves and needLes

COCKROACHES Cockroaches are primarily tropical insects, with only about 50 species present in North America, and many are introduced species. Often these introduced species have limited distribution within the region, and some are essen­ tially restricted to living within buildings, including most of the more notorious commensal species that can be serious household pests. Notable household pest cockroaches include the German cockroach (Blattella germanica),1 brownbanded cockroach (Supella longipalpa),1 American cockroach (Periplaneta americana),2 smokybrown cockroach (Periplaneta fulginosa),2 and Oriental cockroach (Blatta orientalis).2 Outdoors, cockroaches are usually found under fallen leaves, among woodpiles, under wood shingles, around compost piles, and in other sheltered sites during the day. They forage for food at night, and most cockroaches are omnivores that feed on a wide variety of foods, with decaying plant matter usually making up most of the diet; however, a few species do feed on living plants, particularly soft seedlings, and can be plant pests. One cockroach that has been reported to cause serious injury to seedling plants in greenhouses is the Australian cockroach (Periplaneta australasiae). It closely resembles the American cockroach but is slightly smaller and has the edges of the thorax bordered in yellow. Also common in greenhouses and in atrium plantings can be the Surinam cockroach (Pycnoscelus surinamensis),3 a type of burrowing cockroach that can easily tunnel into the soil and mulch around plants. At night they emerge and may chew on soft parts of plants. In Hawaii the Pacific beetle cockroach (Diploptera punctata)3 chews on the bark of cypress and juniper, sometimes causing serious damage. Madeira cockroach (Rhyparobia maderae)3 is a pest of soft fruits (banana, grapes) in tropical areas; it has been periodically introduced on produce, but has been found only in localized areas and is not well established in North America. The green banana cockroach (Panchlora nivea),3 also known as the “Cuban cockroach,” is another non­native species now well established in the Gulf States. It is a very attractive green color and not considered a pest species, limiting its feeding to dead and decaying plant matter. A non­native cockroach that may cause more nuanced effects in gardens is the Asian cockroach (Blattella asahinai). Now well established in much of the southern/southeastern parts of the U.S., it has been shown to be an important predator of insects, notably feeding on eggs of caterpillars. This cockroach is very similar in appearance to the German cockroach, but it differs in habits by rarely entering buildings and is normally found outdoors among fallen leaves and similar debris. The Asian cockroach can also readily fly, unlike its more human­adapted relative, the German cockroach. The cockroaches that are native to the U.S. are best represented by various woods cockroaches (Parcoblatta spp.).1 About a dozen species can be found scattered across much of the U.S., inhabiting wooded areas and feeding on decaying plant matter. Adults typically reach a length of ¾ to 1 inch. Females are a bit smaller than males, and their wings do not extend to fully cover the abdomen. Males have fully developed wings. Only rarely do they enter buildings, but males are good fliers and are often attracted to outdoor lights. 1

Blattodea: Ectobiidae; 2 Blattodea: Blattidae; 3 Blattodea: Blaberidae

54

A C

B D

A. American cockroach. DAVID SHETLAR

B. German cockroach. DAVID SHETLAR

C. Oriental cockroach, various life stages. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Australian cockroach, various life stages.

G. Asian cockroach, nymph.

JIM KALISCH, UNIVERSITY OF NEBRASKA

JOHNNY N. DELL, BUGWOOD.ORG

E. Surinam cockroach.

H. Pennsylvania wood roach.

DAVID SHETLAR

JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Green banana cockroach, Panchlora nivea.

I. Woods cockroach, Parcoblatta virginica.

DAVID SHETLAR

WHITNEY CRANSHAW

E

F

G

H

I

Insects that chew on Leaves and needLes

IMPORTED CABBAGEWORM

(Pieris rapae)1

hosts Essentially all cultivated mustard family plants, including cabbage, broccoli, kale, Brussels sprouts, and collards. Many cruciferous weeds are also important host plants. Damage Larvae chew foliage. Most early feeding occurs on outer leaves, but older larvae tend to feed more intensively on the newer growth and can seriously tunnel the heads of many plants. Distribution Common throughout North America. Appearance The caterpillars are rather sluggish, velvety green with 5 pairs of distinct prolegs. A faint yellow line runs along the back of older larvae. The adult, often known as the cabbage white, has upper wings that are predominantly white, with a slightly dark tip of the forewing. Males have a single black spot on the forewing, whereas females have two such spots. The underside of the wings is yellowish. Life History and Habits In the northern U.S. and Canada, imported cabbageworms spend winter as pupae among plant debris in the vicinity of previously infested plants. The adults are one of the first butterflies to emerge in spring. After a period of mating and egg maturation, females begin to lay their yellow, bullet­shaped eggs on leaves. The eggs are laid singly, often on the underside of the leaf as the female perches on the leaf edge, and eggs may be produced over the course of about three weeks. Larvae hatch in 3–5 days and begin to feed on plants, often first remaining on the outer leaves. Later they tunnel into the head. Larvae are full grown in 2–3 weeks. Pupation occurs in the vicinity of the plant. Two to four generations are typically completed in much of the northern area of the range. In the southern U.S., however, breeding can be continual and as many as six to eight generations may occur.

Other Sulfur and White Butterflies Southern cabbageworm (Pontia protodice)1 is found primarily in the southern U.S. but may disperse northward into the Prairie Provinces. Larvae are much more brightly colored than imported cabbageworm, with black spotting and yellow striping. Feeding habits are similar to those of imported cabbageworm, but southern cabbageworm tends to feed more often on buds and flowers. The adult stage is known as the checkered white butterfly and possesses dark spotting on its white wings. The great southern white (Ascia monuste) is a nearly pure white species that is considerably larger than the cabbage butterfly, and larvae may occasionally be found feeding on radish, cabbage, and other Brassicaceae. It is a southern species, most often found in the Gulf States, and ranges into South America. On occasion it may stray into northern areas as far north as Maryland and Colorado. Alfalfa caterpillar (Colias eurytheme)1 feeds on legumes, including pea, most clovers, alfalfa, and bean. The caterpillars are dark green with a light line running along each side. Adults are orange­yellow butterflies that sometimes become abundant where alfalfa is grown. Closely related and of similar habit is clouded sulfur (C. philodice). Imported cabbageworm damage to broccoli.

 Lepidoptera: Pieridae

1

WHITNEY CRANSHAW

56

A B

C A. Egg of the imported cabbageworm. DAVID CAPPAERT, BUGWOOD.ORG

B. Imported cabbageworm

F

D E

at egg hatch.

DAVID CAPPAERT, BUGWOOD.ORG

C. Late-instar larvae of

imported cabbageworm. WHITNEY CRANSHAW

D. Adult of the imported

cabbageworm, the cabbage white. DAVID CAPPAERT, BUGWOOD.ORG

E. Mating pair of cabbage

white butterflies.

G

DAVID SHETLAR

F. Chrysalis of imported cabbageworm. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

G. Larva of the checkered white,

H

the southern cabbageworm. WHITNEY CRANSHAW

H. Checkered white butterfly. WHITNEY CRANSHAW

I. Larva of the great southern

I white, Ascia monuste.

ALTON J. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

J. Alfalfa caterpillar. JOHN CAPINERA, UNIVERSITY OF FLORIDA

K. Recently emerged adult of

the alfalfa caterpillar, next to its chrysalis.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

L. Clouded sulfur. DAVID CAPPAERT, BUGWOOD.ORG

J

K

L

Insects that chew on Leaves and needLes

SWALLOWTAILS Swallowtails include some of the largest and most striking butterflies found in North America, a welcome addition to most any garden. The caterpillar stages feed on leaves and are also of unusual and interesting appearance, with many having bright warning coloration or large eyespot markings, or are of cryptic appearance resembling bird droppings. Larvae also have the unique habit of being able to extend forked fleshy scent glands (osmeteria) from behind the head when disturbed. These glands also secrete odors that may be distasteful to potential predators.

Parsleyworm/Black Swallowtail (Papilio polyxenes)1 hosts Dill, parsley, and fennel are common hosts. The caterpillars may also be found on carrot, Queen Anne’s lace, celery, caraway, and other plants in the family Apiaceae. Common rue (Ruta graveolens) is also an occasional host. Damage The caterpillars develop primarily by chewing on leaves. When flowering structures are present they may clip flower heads and feed on developing seeds. Distribution Primarily east of the Rockies, although occasionally found in southern California and Arizona. Appearance Adults are known as black swallowtails, large butterflies with a wingspan of 2¼ to 3¼ inches. The primary coloration is shiny black, sometimes with iridescent blue, marked with yellow bands or spots along the edge of the wings. Young caterpillars, known as parsleyworms, are mottled black and white, resembling bird droppings. Later instars dramatically transform to possess prominent banding of yellow, white, and black. When disturbed they will usually extend a yellow­orange scent gland (osmeterium) from behind the front of the head. Life History and Habits Parsleyworm spends the winter as a pupa (chrysalis) attached to tree bark, rocks, the sides of buildings, or other protected locations. Adults typically emerge in late May and early June. After mating females will lay eggs over a period of several weeks, laying a series of individual eggs, usually on younger leaves or flowers of their host plants. Males establish territories they will regularly patrol, waiting for receptive females to pass and chasing away males. Eggs hatch 4–9 days after being laid and the caterpillars feed for about 3–4 weeks, undergoing a series of color changes and patterning as they get older. When full grown, they wander away from the host plant to find a protected spot where they will transform to the pupal stage. The pupa is in the form of a greenish or grayish­brown chrysalis, the colors matching the background to which it is attached. There are typically two generations produced per year in northern areas and three in southern areas. In the early season generations, the adult butterflies emerge from the chrysalis in about two weeks following pupation. In the last generation, the insect remains dormant within the chrysalis and emerges the following year.

58

A

B

C D

E

A. Parsleyworm. DAVID SHETLAR

B. Parsleyworm with osmeteria

everted.

SUSAN ELLIS, BUGWOOD.ORG

C. Egg of the parsleyworm/black

swallowtail. DAVID SHETLAR

F

D. Early-instar parsleyworm larva. DAVID SHETLAR

E. Middle-instar parsleyworm

larva.

JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Chrysalis of the parsleyworm/

black swallowtail. WHITNEY CRANSHAW

G. Parsleyworm preparing to

pupate (prepupa). DAVID SHETLAR

H. Black swallowtail, female. JOHN CAPINERA

I. Black swallowtail, male. DAVID SHETLAR

H

I

G

Insects that chew on Leaves and needLes

swaLLowtaILs

Other Swallowtails The closely related anise swallowtail (Papilio zelicaon) develops on fennel and some plants in the citrus family (Rutaceae). It is found primarily west of the Continental Divide, including the southwestern U.S., and its larvae are sometimes known as the California orangedog. Short-tailed swallowtail (P. brevicauda) occurs in eastern Canada and occasionally damages the foliage of parsnip. Tiger swallowtails are large yellow and black butterflies. In western North America two common species are two-tailed swallowtail (Papilio multicaudatus), developing primarily on chokecherry and ash, and western tiger swallowtail (P. rutulus), associated with willow, cottonwood, and chokecherry. In eastern North America eastern tiger swallowtail (P. glaucus) develops on the foliage of various trees, including wild cherry, sweetbay, basswood, tuliptree, birch, ash, cottonwood, mountain­ash, and willow. Young tiger swallowtail caterpillars are mottled black and white and resemble bird droppings. Older caterpillars may be brown or lime green with prominent eyespots. When sufficiently disturbed, these larvae rear up and extrude their forked yellow scent glands, producing an appearance of a rearing snake. Giant swallowtail (P. cresphontes) is common in much of the southwestern and southeastern U.S., commonly migrating northward. Caterpillars develop on citrus, and the conspicuous caterpillars are sometimes known as orangedogs.  Lepidoptera: Papilionidae

1

Egg of a two-tailed swallowtail.

Late-instar larva, brown form, of the two-tailed swallowtail.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

60

A

B

c D

E

A. Eastern tiger swallowtail. HERBERT A. “JOE” E. PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

F

B. Two-tailed swallowtail. WHITNEY CRANSHAW

C. Early-instar larva of the two-tailed swallowtail. WHITNEY CRANSHAW

D. Giant swallowtail. DAVID SHETLAR

E. Late-instar larva, green form, of the two-tailed

swallowtail, everting osmeterium. JOHN CAPINERA, UNIVERSITY OF FLORIDA

F. Orangedog, larva of the giant swallowtail. DAVID SHETLAR

Insects that chew on Leaves and needLes

BRUSHFOOTED BUTTERFLIES Brushfooted butterflies (Nymphalidae family) are a common group of moderately large butterflies. The upper surfaces of the wings are often brightly colored, but the lower surfaces may be more camouflaged. The front pair of legs is greatly reduced. Although many brush­footed butterflies feed at flowers, others visit sap flows, fermenting fruit, and animal dung. Few species ever seriously damage plants in the caterpillar stage.

Painted Lady/Thistle Caterpillar (Vanessa cardui)1 hosts A wide range of plants, with more than 100 species from several plant families reported. Common hosts include Canada thistle, other thistles, sunflower, Jerusalem artichoke, hollyhock, common mallow, and lupine. Damage Caterpillars chew foliage, sometimes causing significant defoliation. Distribution Painted lady is one of the most widely distributed butterflies in the world, found on almost every continent. It occurs throughout the U.S. and southern Canada as either a winter resident or seasonal migrant. Appearance The caterpillar stage, known as thistle caterpillar, is generally black with some lighter flecking and numerous fleshy dark spines. It is almost always associated with a loose silken shelter it constructs among leaves. The adult stage of the insect is known as painted lady. It is generally orange with irregular black and white spotting on the wings. Life History and Habits Painted lady is an annual migrant in much of North America, spending the winter in more southerly areas, including Mexico. In spring, migrations are northward; in fall, to the south. Females lay eggs singly on host plants. Caterpillars produce a shelter of loose webbing by tying leaves together. When abundant, they extensively defoliate plants, and once the food plant is destroyed, the caterpillars migrate. Pupation occurs in a silvery chrysalis, usually some distance from the food plant. Adults emerge about one week after pupation and usually disperse from the area. Several overlapping generations are produced annually, with returning southward migrations observed in late summer.

Other Brushfooted Butterflies Three other Vanessa species of butterflies occur commonly over much of North America. The red admiral (Vanessa atalanta) is the most distinctively different in appearance, with upper wings having large dark areas and edged with orange stripes and white spots. It can be found throughout the U.S. and southern Canada. Three generations are normally produced in the southern areas, two in much of its North American range, and one generation in the north, where it may not regularly survive winters. Seasonal differences in appearance, with butterflies produced during summer being larger and brighter than those produced in winter. The red admiral is most commonly observed in moist sites, such as near streams, and along edges of woodland. The larvae feed on stinging nettles (Urtica spp.) and false nettle (Boehmeria cylindrica).

62

A C D

E

F

A. Painted lady. WHITNEY CRANSHAW

B. Chrysalis of the painted lady. WHITNEY CRANSHAW

C. Painted lady, side view. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Painted lady larva in thistle. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Larva of the red admiral. DAVID SHETLAR

F. Red admiral. DAVID SHETLAR

B

Insects that chew on Leaves and needLes

BRUshFooted BUtteRFLIes The American lady (V. virginiensis) also has a wide distribution that can include much of North America, although it is most common east of the Mississippi. The range of plants used as larval foods is considerably narrower than that of the painted lady, with everlasting types of composites (e.g., pearly everlasting, sweet everlasting, plantain­leaved pussytoes) being the most common hosts. Three or four generations are produced in the southern U.S., although reproduction may be temporarily suspended during midwinter. Survival through winter in areas with freezing winters is unlikely, and the presence of American lady in these areas results from annual migrations from the south. The West Coast lady (V. annabella) has the most restricted distribution, occurring only in western North America. Larvae develop on nettles and various mallows, including hollyhock. The monarch (Danaus plexippus) is one of the most familiar of the North American butterflies, both large in size and brightly patterned with orange and black. The larvae develop on various milkweeds (Asclepias), are colorfully striped with white, black and yellow, and have two pairs of filaments: a pair arising from the thorax and a pair from the tip of the abdomen. Garden plants that commonly support monarch caterpillars include A. tuberosa (butterfly milkweed), A. syriaca (common milkweed), A. incarnata (swamp milkweed), and A. curassavica (tropical milkweed or bloodflower). All these plants contain compounds (cardiac glycosides) that are toxic to mammals and birds, and both the adult and larval stages store these in their body for defense. The monarch is a migratory species that spends part of the winter in a temporarily dormant state at specific sites where they aggregate. Populations that occur in areas east of the Rocky Mountains migrate to Mexico in autumn and aggregate in forested areas in mountains east of Mexico City. Populations that develop in the Pacific States produce winter aggregations in several different sites of pine forest. Most of these western overwintering aggregation sites are in California, but some monarchs move into western Mexico. The overwintered butterflies resume activity in early spring, laying eggs on newly available host plants on which a new generation develops. Adults of these then disperse northward, where they extensively colonize much of the U.S. and southern Canada. Also developing on milkweeds is the queen (Danaus gilippus). This is a subtropical and tropical species that can breed year­round in the extreme southern areas of Texas and Florida. Elsewhere it occurs as an incidental summer migrant. The larvae are also brightly patterned but have some bluish coloration and 3 pairs of black filaments, which can distinguish them from monarch caterpillars. Of remarkably similar appearance to the monarch is the adult of the viceroy (Limenitis archippus). Larvae of this butterfly develop mostly on willow, and they are generally found throughout North America, particularly in moist sites that support their host plants. The caterpillars and the pupae resemble bird droppings.

64

A

B

C D

E

H

F

G

J

A. American lady. JOHNNY N. DELL, BUGWOOD.ORG

B. Larva of the

American lady. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Western lady. TERRY SPIVERY, USDA-FS, BUGWOOD.ORG

D. Monarch.

I

DAVID SHETLAR

E. Larva of the

monarch butterfly. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Chrysalis of the monarch butterfly. DAVID SHETLAR

G. Mating pair of

monarch butterflies. WHITNEY CRANSHAW

H. Comparison

of monarch (left) and viceroy (right) butterflies. WHITNEY CRANSHAW

I. Larva of the viceroy. HOWARD ENSIGN EVANS

J. Chrysalis of the viceroy

butterfly.

JIM KALISCH, UNIVERSITY OF NEBRASKA

Insects that chew on Leaves and needLes

BRUshFooted BUtteRFLIes Mourning cloak (Nymphalis antiopa) is a dark purple­black butterfly with a yellowish border on the wing. It is one of the few butterflies that winters in the adult stage and may be observed flying about during warm spells in midwinter. Eggs are laid in spring in masses on aspen, cottonwood, poplar, willow, birch, elm, or hackberry. Larvae, known as spiny elm caterpillars, are generally dark colored with purple markings and feed as a group during early instars. Often entire branches are stripped by larval feeding. When full­grown the caterpillars pupate, and the adults that subsequently emerge remain in a reproductively dormant state for the rest of the year. Adults butterflies may periodically feed at flowers, at sap flows, and on rotting fruit through summer and fall, but only a single generation is produced each year. Variegated fritillary (Euptoieta claudia) produces brightly colored larvae covered with fleshy spines. They feed on pansy, violet, Johnny­jump­up, wild flax, and occasionally sedum, Passiflora, alyssum, and purslane. This species can be common and damaging to gardens and is sometimes known as “pansyworm.” It is primarily a southern species, overwintering as a full­grown larva, but it frequently strays into northern states during summer. Hackberry butterfly (Asterocampa celtis) and tawny emperor (A. clyton) are associated with hackberry and sugarberry throughout the range of these plants. Question-mark (Polygonia interrogationis) develops on succulent foliage of elm, basswood, and hackberry in the eastern states. Larvae of the common buckeye (Junonia coenia) feed on plantains, snapdragon, and toadflax. Gorgone checkerspot (Chlosyne gorgone) develops on sunflowers and Lysimachia. 1

 Lepidoptera: Nymphalidae

above: Larva of the variegated fritillary. WHITNEY CRANSHAW

right: Larva of the question mark butterfly.

top: Larva of the hackberry butterfly.

HERBERT A. “JOE” PASS III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

WHITNEY CRANSHAW

above: Larvae of the Gorgone checkerspot. JIM KALISCH, UNIVERSITY OF NEBRASKA

66

B C

D

A E

F

A. Pair of mourning cloak butterflies. WHITNEY CRANSHAW

B. Larva of the mourning cloak,

the spiny elm caterpillar.

STEVEN KATOVICH, USDA-FOREST SERVICE, BUGWOOD.ORG

C. Variegated fritillary. WHITNEY CRANSHAW

D. Question mark butterfly. HERBERT A. “JOE” PASS III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

E. Adult hackberry butterfly feeding

on fluids from a dead raccoon. WHITNEY CRANSHAW

F. Larva of the common buckeye

butterfly.

JERRY A. PAYNE, USDA-ARS, BUGWOOD.ORG

G. Common buckeye butterfly. DAVID SHETLAR

H. Gorgone checkerspot. WHITNEY CRANSHAW

G H

Insects that chew on Leaves and needLes

HORNWORMS AND SPHINX MOTHS Hornworms (Sphingidae family) are among the largest caterpillars found in North America. All are marked by having, at least in the first stages, a prominent “horn” on the hind end. More than 120 species occur on the continent, but only a very few (e.g., tobacco hornworm, tomato hornworm, catalpa sphinx) become sufficiently abundant to regularly cause damage to plants. The majority develop on shade trees and shrubs, where damage is rarely noticed. Adults are strong­flying, heavy­bodied moths known as sphinx moths or hawk moths. The moths feed on nectar from deep­lobed flowers. Those that are active during the day are sometimes known as “hummingbird moths.”

Tomato Hornworm/Fivespotted Hawk Moth (Manduca quinquemaculata)1

Tobacco Hornworm/Carolina Sphinx (Manduca sexta)1

hosts Tomato and tobacco are particularly susceptible to injury. Pepper, potato, and certain nightshade family weeds are also hosts. Damage Caterpillars chew leaves and can defoliate plants rapidly. Fruits, particularly green fruit, may also be chewed. Distribution Both species are found widely throughout the U.S. and southern Canada. Tobacco hornworm tends to predominate in southern areas and tomato hornworm in the north, but distributions overlap considerably. Appearance Larvae develop into large caterpillars, with five pairs of prolegs and a flexible “horn” on the last segment. Most are generally green. Seven diagonal white stripes are present along the side of the tobacco hornworm, and the horn is usually red. Tomato hornworm has a series of V­shaped white markings along the sides, and the horn is often black. Less common dark green or even black forms of tomato hornworm may be present. Adults of both are strong­flying, heavy­bodied moths. The forewings may have a span of up to 5 inches and are generally gray or grayish brown with light wavy markings. Life History and Habits Tomato and tobacco hornworms spend the winter months in the pupal stage, within a chamber approximately 4–6 inches deep in the soil. Adult moths emerge in mid­ to late spring and may migrate long distances. Eggs resemble small pearls and are laid singly on foliage. The newly hatched caterpillars possess a horn that is nearly the same length as the body and subsequently pass through four to five additional larval instars over the course of about a month. Full­grown larvae burrow several inches into soil and create a cell in which pupation occurs. Where these insects can successfully survive winter conditions there are typically two generations produced annually. The adults are very strong fliers and in more northern areas, incidence of tomato and tobacco hornworms from year to year may be strongly influenced by migrations of moths originating from more southerly areas.

68

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A.Tomato hornworm. WHITNEY CRANSHAW

B.Egg of a tomato hornworm. DAVID SHETLAR

C.Tomato hornworm caterpillars

showing different color morphs. JIM KALISCH, UNIVERSITY OF NEBRASKA

D.Adult of the tomato hornworm. DAVID SHETLAR

E.Tomato hornworm,

young larva. DAVID SHETLAR

F.Adult of the tobacco hornworm. JOHN CAPINERA, UNIVERSITY OF FLORIDA

G.Tobacco hornworm. WHITNEY CRANSHAW

H. Pupa of a tobacco hornworm. JOHN CAPINERA, UNIVERSITY OF FLORIDA

E

F

G H

Insects that chew on Leaves and needLes

hoRnwoRMs and sPhInX Moths

Other Common Hornworms Whitelined sphinx (Hyles lineata)1 is the most widely distributed sphinx moth in North America. It is particularly common throughout western North America, where it is familiar to gardeners as the most commonly encountered “hummingbird moth” and is marked with a prominent white band on the forewing. Larvae develop on a wide variety of plants, including portulaca, evening primrose, and grape. They can be highly variable in color, ranging from bright green to black. Two generations are produced annually, with overwintering occurring as a pupa in soil. Adults of great ash sphinx (Sphinx chersis)1 are also commonly observed as day­flying hummingbird moths. Larvae of this species develop on ash, lilac, and privet. Larvae of achemon sphinx (Eumorpha Full-grown achemon)1 are unusual in that they lose the terminal caterpillar of the horn during the last larval molt. Instead, the last­instar pandorus sphinx. HERBERT A. “JOE” PASE larva is marked by a prominent eyespot at the hind end. III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG The caterpillars develop on Virginia creeper, grape, and related vines. Apparently there is one generation pro­ duced per year, with full­grown caterpillars most commonly observed in late August and early Septem­ ber. The achemon sphinx has broad distribution throughout most of the U.S. The closely related pandorus sphinx (E. pandorus) has a more restricted distribution to the eastern half of North America, but similarly feeds on grape family plants. Also occurring on Virginia creeper and grape in the eastern U.S. is Virginia creeper sphinx (Darapsa myron).1 Catalpa sphinx (Ceratomia catalpae)1 occurs throughout most of the eastern U.S., being particularly abundant in the southern states, where it may occur from Florida through parts of Texas. It develops on all species of catalpa and is sometimes abundant enough to defoliate trees, usually in August and September. Up to four generations may be produced annually in southern parts of the range. The caterpillars, sometimes known as “catawba worms,” are highly prized as fish bait in some locations. Related species include elm sphinx (C.  amyntor), which feeds on elm and occasionally birch, basswood, and cherry, and waved sphinx (C. undulosa), which develops on ash, privet, oak, and hawthorn. Walnut sphinx (Amorpha juglandis) occurs on black walnut, hickory, beech, butternut, and top: Catalpa sphinx moth larva shortly after egg hatch. DAVID SHETLAR pecan in eastern North America. It occurs over much of above: Larva of the elm sphinx. the Continent east of the Rocky Mountains. WHITNEY CRANSHAW 70

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A. Adult of the whitelined sphinx.

F. Larva of the great ash sphinx.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

B. Whitelined sphinx caterpillar, green phase.

G. Catalpa sphinx larva,

WHITNEY CRANSHAW

HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

C. Whitelined sphinx

caterpillar, dark phase. WHITNEY CRANSHAW

D. Larva of the achemon

sphinx, brown morph.

HAROLD LARSEN, COLORADO STATE UNIVERSITY

E. Larva of the achemon

sphinx, green morph. WHITNEY CRANSHAW

light phase.

H. Catalpa sphinx larva, dark phase. DAVID SHETLAR

I. Adult of the achemon

sphinx.

WHITNEY CRANSHAW

J. Adult of the catalpa sphinx. HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE

Insects that chew on Leaves and needLes

hoRnwoRMs and sPhInX Moths Sweetpotato hornworm (Agrius cingulata), also known as pink-spotted hawk moth, is a tropical and subtropical species that feeds on sweetpotato and some related weeds. It is common in the southern U.S., occasionally straying into the Midwest. Hornworms in the genus Hemaris are among the smallest in the family. Adults, sometimes known as “clearwing sphinx” or “bumble bee clearwings” often fly during the day. They have an unusual appearance, with wings largely clear of scales and a heavy body form so they somewhat resemble a large bumble bee. Larvae develop on various shrubs, including honeysuckle, snowberry, cherry, plum, and cranberry. Hummingbird clearwing (H. thysbe), found primarily in eastern North America, and the broadly distributed snowberry clearwing (H. diffinis) are the dominant species. Poplar and willow host many kinds of hornworms. Twinspotted sphinx (Smerinthus jamaicensis) and one-eyed sphinx (S. cerisyi) are both quite common in northern areas. Twinspotted sphinx occurs primarily in the eastern half of the northern U.S. and southern Canada and one­eyed sphinx in the western half, although ranges overlap. Some of the largest sphinx moths are the big poplar sphinx (Pachysphinx occidentalis) and the modest sphinx (P. modesta), restricted to the western half of North America.  Lepidoptera: Sphingidae

1

right: Late-instar larva of the modest sphinx, Pachysphinx modesta. DAVID LEATHERMAN below: Pair of western poplar sphinx. WHITNEY CRANSHAW

A. Adult sweetpotato hornworm. KARAN A. RAWLINS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

B. Sweetpotato hornworm larvae, showing

different color morphs.

FOREST AND KIM STARR, STARR ENVIRONMENTAL, BUGWOOD.ORG

C. Adult of the hummingbird clearwing moth. DAVID CAPPAERT

D. Larva of the hummingbird clearwing moth. WHITNEY CRANSHAW

E. Adult of the hummingbird clearwing moth. DAVID SHETLAR

F. Snowberry sphinx. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Larva of the snowberry sphinx. JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Adult of the twinspotted sphinx. HOWARD ENSIGN EVANS.

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Insects that chew on Leaves and needLes

PROMINENT MOTHS/NOTODONTIDS Several caterpillars of the prominent moth family (Notodontidae) are associated with trees and shrubs. In general form, the caterpillars somewhat resemble climbing cutworms but often have distinct markings or fleshy projections. A few species are pests of trees and shrubs, and these are usually observed feeding in groups. In response to disturbance, members of the feeding group typically arch and twitch to deter predators.

Walnut Caterpillar (Datana integerrina)1 hosts Walnut, butternut, pecan, and hickory. Damage Larvae chew leaves, first skeletonizing and later consuming most of the leaf except for main veins. Distribution Much of the eastern U.S. but particularly common in the central and southcentral states. Appearance Full­grown caterpillars are about 2 inches long, dark purple to gray, with some thin white to yellow stripes along the sides of a body generally clothed in long hairs. When disturbed, a group of larvae usually arch their heads and abdomens in a defensive posture. Adults are moderate­sized brown moths with a wingspan of about 2 inches and are marked with some dark lines. Life History and Habits Winter is spent as a pupa, in a cell constructed in soil in the vicinity of previously infested trees. Adults emerge in mid­ to late spring, and females lay eggs in masses. Upon hatching, the caterpillars feed gregariously, first skeletonizing leaves and later feeding more generally. Larvae periodically migrate from foliage to large branches and trunks, where they rest in masses and molt, often in synchrony. The full­grown caterpillars often wander considerable distances before pupating. Two generations are produced in the southern states, with adults emerging in midsummer. One generation is common in northern areas.

Other Notodontids/Prominent Moths on Shade Trees Yellownecked caterpillar (Datana ministra) is a common species in the Appalachian Mountains and may occur in much of the eastern U.S. The caterpillars are marked with a bright yellow patch behind the head. Young larvae are first orange but turn black in the later instars. They have a wide host range, including many deciduous fruit, nut, and shade trees. Azalea caterpillar (D. major) is often a serious defoliator of azalea in the southeastern U.S. The caterpillars are brightly patterned, yellow and black with a red head and legs. One generation per year is typical, with peak injury in mid­ to late summer.

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A. Walnut caterpillars, late instar. DAVID SHETLAR

B. Walnut caterpillar, adult. DAVID SHETLAR

C. Walnut caterpillar egg mass. HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

D. Walnut caterpillars massed on branch. DAVID SHETLAR

E. Walnut caterpillars at egg hatch. DAVID SHETLAR

F. Yellownecked caterpillars. DAVID SHETLAR

G. Yellownecked caterpillars. DAVID SHETLAR

F

G

Insects that chew on Leaves and needLes

PRoMInent Moths/notodontIds Redhumped caterpillar (Schizura concinna) is probably the most commonly encountered and widespread of the prominent caterpillars in North America. Caterpillars are marked with a pronounced reddish hump behind the head, and during early development they feed gregariously, sometimes stripping individual branches. Apple and crabapple are among the common hosts, although this species develops on many woody plants. One generation is produced per year. The closely related unicorn caterpillar (S. unicornis) is an unusual brown and green caterpillar with a large fleshy projection on the first segment of the abdomen. Of very similar appearance is false unicorn caterpillar (S. ipomoeae), sometimes known as “morning glory prominent.” Dark markings on the head and abdomen, absent on false unicorn caterpillar, can distinguish the larvae. Both species of unicorn caterpillars are found throughout most of North America and may feed on a wide range of deciduous trees and shrubs. Orangehumped mapleworm (Symmerista leucitys) is a northern species that develops primarily on sugar maple. The caterpillars have an orange­red head and longitudinal black, yellow, and white striping with an orange marking on the hind end. Young stages feed gregariously and skeletonize the upper leaf surface. Older caterpillars are solitary and feed along the leaf margins. Redhumped oakworm (S. canicosta) also occurs in the northeastern U.S. and southeastern Canada, where it develops primarily on white and bur oak. Basswood, sugar maple, paper birch, beech, and elm are less common hosts. Saddled prominent (Heterocampa guttivitta) is a caterpillar of bizarre appearance. First­instar larvae have black antler­like horns behind the head that are lost at the first molt. Full­grown caterpillars are about 1½ inches long, generally green with an orange­red “saddle marking” on the middle. The species is most common in New England. Variable oakleaf caterpillar (Lochmaeus manteo) occurs over a broader area of eastern North America, from southern Ontario to northern Texas. White oak is the preferred host, but several other trees are occasionally infested. Damage is most common in the southern states, where two generations per year can occur. This caterpillar can also cause blistering of exposed skin from a formic acid mixture it can spray when disturbed. The California oakworm (Phryganidia californica)1 is a common caterpillar along coastal areas of California and southern Oregon and is associated with coast live oak. Caterpillars survive the winter as early­stage larvae on the underside of leaves, causing minor skeletonizing. They rapidly develop during early spring and may defoliate trees during outbreaks. They then pupate on bark of trunks, suspended from limbs or on nearby vegetation. Adults, which are tan­gray moths with a wingspan of approximately 1¼ inches, are weak fliers and subsequently lay their eggs in the near vicinity of previously infested plants. Eggs are laid as small masses on twigs or leaves during late summer and early fall. Two generations per year are normally produced; a third generation is sometimes produced if favorable conditions occur.  Lepidoptera: Notodontidae

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A. Redhumped caterpillar.

F. Redhumped oakworm.

LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

B. Unicorn caterpillar.

G. Saddled prominent.

JIM KALISCH, UNIVERSITY OF NEBRASKA

BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

C. False unicorn caterpillar. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

D. Adult of the unicorn caterpillar. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Orangehumped oakworm. USDA-FOREST SERVICE REGION 2, BUGWOOD.ORG

H. Variable oakleaf caterpillar. WHITNEY CRANSHAW

I. California oakworm. JACK KELLY CLARK, UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

Insects that chew on Leaves and needLes

GIANT SILKWORMS/ROYAL MOTHS The giant silkworms (Saturniidae family) include the largest caterpillars that can be encountered, with some more than 5 inches long. All feed on leaves of trees and shrubs, and individual caterpillars consume impressive amounts toward the end of their life cycle, usually in mid­ to late summer. Rarely are they abundant enough to cause significant injury; however, their presence is mostly a curiosity—or even a source of wonder—because of their large size and appearance. Furthermore, populations of several species have been in sharp decline for many years, due to several human­assisted causes. Adults, often known as royal moths, are large moths that may have a wingspan exceeding 6 inches. Adults do not feed and thus die a few days after emergence from the cocoon. Moths are usually present in late spring or early summer.

Cecropia Moth (Hyalophora cecropia)1 hosts At least 50 species of deciduous trees and shrubs are hosts of larvae. Boxelder, sugar maple, wild cherry and plum, apple, alder, birch, dogwood, willow, lilac, ash, and viburnum are common hosts. Damage Cecropia moth caterpillars can be among the most conspicuous late­season defoliators of shrubs. Because the feeding occurs late in the season, however, it causes little, if any, plant injury. Distribution Primarily east of the Rockies. Appearance The larvae are large, sluggish, sea green caterpillars, from 3 to 4 inches long. They possess numerous colored knoblike tubercles—pale blue along the sides, orange on the thorax, and yellow on the abdomen. Adults are large and colorful moths with a wingspan of 5½ to 6½ inches. They have brownish gray wings with white crescent­ shaped eyespots, a dark spot near the tip of each forewing, and red­bordered crossbands on the abdomen. The pupa develops in a tough cocoon attached along its entire length to a twig. Life History and Habits Winter is spent as a pupa in the cocoon, usually attached to a small branch. Adults emerge in late spring. They do not feed, but they mate and females lay eggs on twigs over the course of a few days before dying. The caterpillars then begin to feed on leaves and develop over a period of 2–3 months. All stages of cecropia moth caterpillars bear prominent tubercles on the body, but the caterpillars develop more intense coloration as they age. One generation is produced per year. Cocoon of the cecropia moth.

Other Giant Silkworms/Royal Moths

DAVID SHETLAR

Hickory horned devil (Citheronia regalis)1 is a caterpillar of bizarre appearance that may be 5 inches long. Generally blue green, it has numerous spikes, particularly two long curving pairs on the thorax, giving it a rather dragonlike appearance. It is found in much of the eastern U.S., being more common in the southern states. Hickory, walnut, and a few other trees and shrubs may host the caterpillars. When feeding is completed, the larvae descend trees and walk about in search of soil in which to pupate. Adults are large moths with prominent orange markings and stripes known as regal moths. 78

B

A

A. Cecropia moth, male. DAVID SHETLAR

B. Late-instar cecropia

moth caterpillar.

JOHN GHENT, BUGWOOD.ORG

C. Cecropia moth eggs. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Early-instar cecropia

moth caterpillars.

JIM KALISCH, UNIVERSITY OF NEBRASKA

D

E

F

G

E. Hickory horned

devil, full-grown larva. DAVID SHETLAR

F. Hickory horned

devil, young larva. DAVID SHETLAR

G. Regal moths, adults of

the hickory horned devil. DAVID SHETLAR

C

Insects that chew on Leaves and needLes

GIant sILKwoRMs/RoYaL Moths Luna moth (Actias luna)1 is one of the most distinctive moths of North America, having pale green wings developed into an elongate “swallowtails” and marked with a yellow spot. Larvae are translucent pale green with a pale yellow line along the lower side and feed on a wide variety of nut, fruit, and shade trees. The species is known from parts of Texas and Nebraska eastward but has become considerably less abundant in recent decades. Larvae of Polyphemus moth (Antheraea polyphemus)1 are stout­bodied, apple green, and only sparsely marked by spines. This species is widely distributed throughout much of North America and feeds on many deciduous trees and shrubs in late summer. Dogwood, oak, willow, maple, and birch are among the common plants on which the caterpillars develop. Caterpillars of Promethea moth (Callosamia promethea)1 are pale bluish green and possess four prominent red­orange spikes near the head and one yellow spike near the rear. They occur in the eastern U.S. and southeastern Canada. Hosts include cherry, magnolia, tuliptree, ash, and lilac. The closely related tuliptree silkmoth (C. angulifera) develops solely on tuliptree and with a distribution in eastern North America that matches its host plant. Imperial moth (Eacles imperialis)1 develops on a wide range of shade trees, including some conifers as well as deciduous trees. Most often the caterpillars are green and covered with short, light blue­green hairs. Darker morphs sometimes occur that are largely brown or even black.

above: Cocoon of the Polyphemus moth cut away to expose pupa. WHITNEY CRANSHAW left: Caterpillar of the luna moth. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

below: Promethea moth caterpillar. TOM MURRAY

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A. Luna moth. DAVID SHETLAR

B. Polyphemus moth caterpillar. DAVID SHETLAR

C. Caterpillar of the promethea moth. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

D. Polyphemus moth. DAVID SHETLAR

E. Imperial moth caterpillar. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

F. Imperial moth caterpillar. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Imperial moth. JIM KALISCH, UNIVERSITY OF NEBRASKA

G

Insects that chew on Leaves and needLes

GIant sILKwoRMs/RoYaL Moths Pandora moth (Coloradia pandora)1 is a western species associated with pines. It has had several historical outbreaks, and the caterpillars have sometimes been used as a food source by Native Americans. The life cycle requires 2 years to complete, with partially grown larvae wintering on the tree during the first year and then moving to the soil to pupate in a cocoon following the second year. Greenstriped mapleworm (Dryocampa rubicunda)1 is associated with maple throughout the eastern U.S. and is particularly common in the southern half of its range where outbreaks sometimes are recorded. Caterpillars possess a cherry red head and yellow­green body with seven dark green lines running the length. The insect is also marked with two slender, flexible horns behind the head. Orangestriped oakworm (Anisota senatoria)1 occurs in much of the eastern half of the U.S., excluding some of the southeastern states. It feeds on oak and occasionally causes extensive defoliation in late summer. Spiny oakworm (A. stigma) is marked by two prominent spines on the thorax. It ranges east from southern Ontario to parts of Texas and develops on oak and hazel. Io moth (Automeris io)1 is one of the smaller giant silkworms, reaching about 3 inches when mature. The larvae possess numerous stinging hairs that produce a painful reaction on touch. Io moth caterpillars are the most widespread and commonly encountered of the caterpillars in North America that can produce painful stings. Larvae are large, pale green caterpillars with a lateral stripe of pink and creamy white down each side, covered with clusters of branching spines. They develop on a wide range of deciduous shade trees including willow, elm, apple, maple, hickory, and sycamore and are about 3 inches long at maturity. Pupation occurs in a cocoon, and the stinging hairs of the larvae coat the cocoon. Adults have a wingspan of 2½ to 3 inches, the females with lightly patterned purplish red wings, the males smaller with yellowish wings, and both with a large circular black eyespot on the hindwings. One generation is produced in most areas, but two can occur in the more southern states. A few species of Hemileuca1 species, sometimes known as “buck moths,” are occasional tree pests. Older larvae are generally dark and possess numerous tufts of branched spines. The spines are attached to poison glands capable of producing a painful sting, although not as painful as that of Io moth. The most common western species, Nevada buck moth (H. nevadensis), develops on poplar and willow. Eastern buck moth (H. maia) is an eastern species that feeds on scrub, live, blackjack, and dwarf chestnut oak. New England buck moth (H. lucina) is restricted to the New England States and feeds on oak, black cherry, willow, gray birch, and blueberry. Adults of all buck moths are fairly large, fly during fall days, and have wings prominently patterned with white and black. Egg masses survive winters and the larvae feed over much of the spring and summer months.  Lepidoptera: Saturniidae

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A. Pandora moth caterpillar. DAVID LEATHERMAN

B. Greenstriped

F. Io moth caterpillar. STEVEN KATOVICH, USDA-FOREST SERVICE, BUGWOOD.ORG

G. Adult of the Io moth.

mapleworm adult.

RONALD J. BILLINGS, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

WILLIAM CIESLA, FOREST HEALTH MANAGEMENT INTERNATIONAL, BUGWOOD.ORG

H. Caterpillar of the eastern buck moth, Hemileuca maia.

C. Greenstriped

mapleworm.

GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD. ORG

D. Orangestriped

oakworm.

DAVID SHETLAR.

E. Spiny oakworm. DAVID SHETLAR

GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD. ORG

I. Adult of the eastern buck moth, Hemileuca maia. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD. ORG

I

Insects that chew on Leaves and needLes

SLUG CATERPILLARS/FLANNEL MOTHS AND OTHER STINGING CATERPILLARS The slug caterpillars (Limacodidae) are often bizarre in appearance and attract attention but are rarely abundant. Most larvae possess prominent spines and bright coloration and may be an unusual shape. The spines are highly irritating upon contact and can produce a painful reaction. Because of the stinging hairs, some species are locally known as “asps.” Saddleback caterpillar (Sibine stimulea)1 is among the most commonly encountered species, found in much of the eastern half of the U.S. and particularly abundant in the Atlantic States. Larvae are brown with a pronounced green saddle­shaped area over the center of the body. Colorful sharp spines, connected to poison gland cells, extend from both front and back and are extremely painful. Saddleback caterpillars feed on apple, pear, cherry, corn, canna, lily, dahlia, and many other plants but are never abundant enough to cause serious plant injury. The pupa occurs in a cocoon, and the stinging hairs are retained on the surface. Adults fly in July and August in the north and year­round in the extreme south. Stinging rose caterpillar (Parasa indetermina)1 also has tufts of stinging hairs, but the general color is reddish or orange red with striping down the center of the back. Common hosts include wild rose, redbud, oak, hickory, bayberry, wild cherry, and sycamore. Two Euclea1 species (E. delphinii, E. nanina) with stinging hairs, known as “spiny oak slugs” feed on a wide variety of trees and shrubs in eastern North America. Caterpillars of hag moth (Phobetron pithecium)1 have numerous long, curved spines along the sides and particularly enlarged areas on the third, fifth, and seventh segments. The spines are connected to poison glands, and contact with the spines produces a painful reaction. Larvae feed on many deciduous trees and shrubs, including wild rose, sassafras, alder, and spirea. Another species with stinging hairs that is common in parts of the southern U.S. is puss caterpillar (Megalopyge opercularis).2 Larvae are densely covered in long hairs that may be yellowish, reddish brown, or mouse gray. The young larvae typically feed in groups, skeletonizing the leaf surfaces of many deciduous trees including oak, elm, hackberry, and sycamore. Two generations are produced annually. A related species that occurs in the southeastern U.S. is hackberry leaf slug (Norape ovina).2 Larvae have six small tufts of stinging hairs on each segment and feed on several woody plants, particularly redbud, red maple, and hackberry. The adult is known as the white flannel moth. A related species found in southwestern states that also has stinging hairs is mesquite stinger (N. tenera).  Lepidoptera: Limacodidae; 2 Lepidoptera: Megalopygidae

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A. Saddleback caterpillar. DAVID SHETLAR

B. Stinging rose caterpillar. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

C. Adult of the stinging rose caterpillar. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

D. A spiny oak slug. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

E. Caterpillar of the hag moth. JERRY A. PAYNE, USDA-ARS, BUGWOOD.ORG

F. Puss caterpillar. DAVID SHETLAR

G. Hackberry leaf slugs. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

G

Insects that chew on Leaves and needLes

TUSSOCK MOTHS The term “tussock moth” is loosely applied to certain caterpillars, within two families, that are thickly covered with hairs and have patches of hairs clumped together in dense tufts. The hairs of many species can be very irritating to skin and eyes.

Whitemarked Tussock Moth (Orygia leucostigma)1 hosts A wide variety of trees and shrubs, including apple, basswood, elm, sycamore, maple, birch, pyracantha, live oak, mimosa, and redbud. Some conifers are occasional hosts. Damage Larvae chew leaves, occasionally causing significant defoliation. Distribution Generally distributed east of the Great Plains. Also known from British Columbia. Appearance Larvae are cream­colored overall with coral red heads. On four segments of the abdomen distinctive brushlike tufts of white or yellowish hairs are present, and there are pencil­like tufts of hairs at both the hind and front ends. Adult females are wingless, about ½ inch in length. Adult males are grayish brown with a wingspan of about 11⁄5 inches and a distinctive white spot at the base of the forewing. Life History and Habits Winter is spent as eggs that were laid adjacent to wherever females previously pupated. Eggs hatch in mid­ to late spring, and the early­stage larvae skeletonize leaves. Later­stage larvae feed more generally and become full grown 3–4 weeks after egg hatch. They often wander a considerable distance before pupating, and the pupal stage occurs in a cocoon mixed with hairs of the larvae. A second generation is common in much of the range, with peak feeding in midsummer.

Related and Similar Species Douglas-fir tussock moth (Orgyia pseudotsugata)1 is a western species ranging from Colorado into the Pacific Northwest. It feeds on spruce, Douglas­fir, and white fir. Overwintered egg masses hatch shortly after bud break, and the young larvae first consume emergent new growth. Defoliation typically is concentrated on the upper areas of the plant, and serious defoliation can cause tree crowns to die and trees to become susceptible to bark beetles. Sensitization to the hairs of the caterpillars is reported in some people following outbreaks of this insect, particularly when the full­grown larvae wander off the tree in search of pupation sites. Males can fly but females are wingless, mating and laying eggs among the cocoon and pupal skin fragments in early summer. One generation is produced per year. Western tussock moth (O. vetusta) is found throughout the Pacific States. Larvae develop on various fruit and nut trees, hawthorn, manzanita, oak, pyracantha, toyon, walnut, and willow. Two cycles of feeding occur annually, in spring and in late summer/early fall. Rusty tussock moth (O. antiqua) is widely distributed and found throughout much of the northern U.S., southern Canada, and into northern California. It is rarely seriously damaging but has a wide host range including many hardwood trees and shrubs and conifers. The common name relates to the rusty color of the adult male moth. Caterpillars of the milkweed tussock moth (Euchaetes egle)1 feed on the leaves of various milkweeds and, occasionally, on dogbane. Eggs are laid as masses on the underside of leaves and the early­stage larvae feed as a group. Later larvae disperse throughout the plant and develop prominent tufts of black, white, and orange hairs. Milkweed tussock moth occurs throughout eastern North America and undergoes two generations per year. 86

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A. Whitemarked tussock moth. DAVID CAPPAERT, BUGWOOD.ORG

B. Female whitemarked tussock moth laying eggs. DAVID SHETLAR

C. Douglas-fir tussock

moth egg mass at hatching. DAVID LEATHERMAN

D. Douglas-fir tussock

moth caterpillar.

WILLIAM CIESLA, FOREST HEALTH MANAGEMENT INTERNATIONAL, BUGWOOD.ORG

E. Adult male Douglas-fir

tussock moth.

DAVID LEATHERMAN

F. Adult female Douglas-fir

tussock moth next to cocoon. JERALD E. DEWEY, USDA-FOREST SERVICE, BUGWOOD.ORG

G. Western tussock

H moth caterpillar. DAVID SHETLAR

H. Milkweed tussock moth caterpillar. DAVID SHETLAR

Insects that chew on Leaves and needLes

tUssocK Moths Satin moth (Leucoma salicis)1 is a European species found in the northeastern and northwestern U.S. and adjacent areas of Canada. Several shade trees and shrubs are hosts, including poplar, willow, aspen, and oak. The life history is unusual, with winter spent as a partially grown larva in a silken bag attached to a tree, a habit somewhat resembling that of bagworms (page 116). Peak feeding occurs when the larvae emerge to feed on new growth in spring. The pupa is jet black and is produced in late spring, with adults active in early summer. Eggs are produced during this time. They later hatch and produce larvae that feed for a brief period as leaf skeletonizers, until they move to winter shelters. Hickory tussock moth (Lophocampa caryae)1 feeds from July through September on a wide range of deciduous trees and shrubs, including nut trees, apple, basswood, oak, and birch. Eggs are laid in masses, and subsequent early­stage caterpillars feed as a group, later dispersing. All stages of the caterpillars have a black head and are pale yellow, often becoming white as they complete development. Pupation in a cocoon occurs around the base of plants and is the wintering stage. Hickory tussock moth occurs over the northeastern quarter of the U.S. and in southeastern Canada. Sycamore tussock moth (L. harrisii) develops on sycamore and plane tree in the eastern U.S. Eggs are laid in late spring with subsequent peak larval feeding in mid­ to late summer. Caterpillars of banded tussock moth (Halysidota tessellaris),1 also known as the “pale tussock moth,” feed on various flowers as well as the foliage of sycamore, alder, oak, hickory, and other plants. Oleander caterpillar (Syntomeida epilais)1 feeds on oleander in Florida and southern Georgia. Eggs are laid as masses, and the caterpillars feed in groups, moving up and down the plant as they get older. They are hairy caterpillars, bright orange with tufts of long black hairs. At pupation they continue to aggregate, pupating in a group. Adults are steel blue in color with polka­dotted wings and an orange tip to the abdomen. Moths fly during the day. A related species that feeds on oleander, spotted oleander caterpillar (Empyreuma affinis)2 occurs in extreme southern Florida and the Florida Keys. American dagger moth (Acronicta americana)2 is a predominately yellow caterpillar with dark tufts of pencil­hairs. It feeds primarily on maple and boxelder, infrequently on apple, basswood, oak, and willow. The caterpillars feed at night and have the unusual habit of cutting the partially consumed leaf at the petiole before retreating to daytime shelter. This species is widely distributed east of the Rockies. Related species that feed on poplar, cottonwood, and willow are cottonwood dagger moth (A. lepusculina) and poplar dagger moth (A. leporina). Habits and general appearance of the caterpillars are similar to those of American dagger moth.  Lepidoptera: Erebidae; 2 Lepidoptera: Noctuidae

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Hickory tussock moth caterpillars. DAVID SHETLAR

Caterpillar of the poplar dagger moth. DAVID SHETLAR

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A. Satin moth caterpillar.

F G

BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

B. Sycamore tussock moth caterpillar. JAMES SOLOMON, USDA-FOREST SERVICE, BUGWOOD.ORG

C. Caterpillar of the banded (pale) tussock moth. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

D. Adult of the oleander caterpillar laying eggs. DOUG CALDWELL, UNIVERSITY OF FLORIDA

E. Spotted oleander caterpillar (above) and

oleander caterpillar (below).

DOUG CALDWELL, UNIVERSITY OF FLORIDA

F. Adults of the American dagger moth. WHITNEY CRANSHAW

G. Caterpillar of the American dagger moth. DAVID SHETLAR

Insects that chew on Leaves and needLes

GYPSY MOTH (Lymantria dispar)1 hosts Caterpillars of the gypsy moth feed on an extremely wide range of plants. Oak and aspen are among the trees that are particularly favored, but plants as diverse as hemlock, white pine, and poison ivy are also eaten by gypsy moth caterpillars. Damage Larvae chew leaves of plants during late spring. Gypsy moth is an outbreak species of forests and causes extensive defoliation during outbreak events. Outbreaks persisting for two or more consecutive years produce significant weakening of plants so they become disposed to secondary pests, such as twolined chestnut borer. Droppings (frass) and leaf fragments produced by caterpillar outbreaks can produce serious nuisance problem issues. Distribution Since its original, accidental introduction outside Boston in 1868, gypsy moth has steadily extended its range. It is currently found in a broad swath over much of the northern U.S. as far west as parts of eastern Minnesota and southward into the Carolinas. Isolated infestations have been found in almost every state because of the movement of egg masses on plant materials and other infested items moved in commerce. A strain subspecies of the gypsy moth native to parts of Russia, known as Asian gypsy moth, produces females that are capable of flight. This insect has on occasion been introduced into the Pacific Northwest. Strong efforts to limit its introduction and to eradicate known infestations are ongoing by government agencies in both the U.S. and Canada. Appearance Larvae are generally mottled gray and have pairs of colored tubercules, blue in front and red in back. They have numerous hairs on the body that can be irritating to human skin. Male moths are generally dark brown with wavy darker markings across the wings. Females have wings that are generally white with dark wavy stripes; however, they are incapable of flight. Life History and Habits Winter is spent as eggs laid in a mass covered with hairs from the body of the female. Eggs usually hatch in April, and the young larvae often move to the tips of branches where many may be dispersed by wind (ballooning). Larval development typically involves five (male) or six (female) caterpillar stages (instars) completed over the course of about 6 weeks. Most feeding occurs at night, with the larvae moving to trunks and branches during the day to rest and molt. Later stages often feed during the day, however, particularly during outbreaks. The larvae may settle on plants for pupation or wander and pupate on rocks, adjacent vegetation, sides of buildings, and other upright surfaces in the vicinity. The pupa is naked and only loosely covered with and attached by silk. Adults emerge about 2 weeks later. The male adult is a strong flier, but females are flightless and lay eggs near where they pupate. After mating, females lay a single egg mass, typically containing more than 250 eggs and covered with pale yellow hairs from the female’s abdomen. The eggs require an extended cold period for hatching and remain dormant until the following spring. Lepidoptera: Erebidae

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A. Late-instar caterpillar of the gypsy moth. DAVID SHETLAR

B. Egg mass of the gypsy moth. DAVID SHETLAR

C. Adult male gypsy moth. DAVID SHETLAR

D. Adult female gypsy moth laying eggs. DAVID SHETLAR

E. Gypsy moth egg mass at egg hatch. DAVID SHETLAR

F. Larvae and pupae of gypsy moth

on a tree trunk. DAVID SHETLAR

Insects that chew on Leaves and needLes

WOOLLYBEARS The term “woollybear” is loosely applied to some densely hairy caterpillars formerly of the family Arctiidae (now family Erebidae, subfamily Arctiinae). The term “woollybear” is most commonly used for those species that can be observed wandering on the ground late in the growing season. Yellow woollybear (Spilosoma virginica)1 is a generalist leaf feeder that can occur on almost all garden plants and is very widely distributed in North America. The caterpillars are covered with fine hairs of uniform color. Young stages are always quite pale, and yellowish coloration predominates throughout development. Brown forms sometimes occur. Adults have nearly pure white wings that span 1½ to 2 inches. One black spot occurs on the forewing, three spots on the hindwing. Winter is spent as a pupa in a loose cocoon mixed with hairs from the larvae, under debris and other protected sites around the soil surface. First­generation adults emerge in midspring, and females lay eggs in masses on leaves. The newly hatched larvae originally feed as a group and skeletonize the undersurface of leaves. They disperse and feed more generally as they get older. They then pupate and produce a second generation. Those that do not go into winter dormancy at this point produce a third generation, after which the overwintering pupae occur. Saltmarsh caterpillar (Estigmene acrea)1 is the most common damaging species of woollybear, particularly in the southwestern U.S. Feeding habits are similar to those of yellow woollybear. Caterpillars are originally dark brown but later turn variable colors, including yellowish brown or black. Winter is spent as a mature larva in the cocoon, and pupation occurs in spring. The adult, known as the acrea moth, has white forewings marked with numerous dark spots. Hindwings of the male are yellow, of the female white. There may be three or four generations a year in southern areas, a single generation in the north. Banded woollybear (Pyrrharctia isabella)1 rarely damages crops, limiting most feeding to a wide range of weeds. The caterpillar is well recognized, however, by its broad brown central band bordered by black. The central band does tend to widen as the caterpillars mature, but there is no basis for the folk legend that its relative width predicts the severity of the upcoming winter. Winter is spent as a nearly full­grown caterpillar that resumes feeding for a brief period the following spring before pupating. Adults are known as Isabella moths. One to two generations are produced annually.  Lepidoptera: Erebidae (Arctiinae)

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A. Banded woollybear.

E. Saltmarsh caterpillar.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

B. Yellow woollybear.

F. Saltmarsh caterpillar.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

C. Adults of the banded woollybear.

G. Saltmarsh caterpillar adult

WHITNEY CRANSHAW

D. Adult of the yellow woollybear. DAVID SHETLAR

with egg masses. ROBERT HAMMON

Insects that chew on Leaves and needLes

CLIMBING CUTWORMS AND ARMYWORMS Caterpillars in the family Noctuidae that feed at or just below the soil and that cut plants are usually known as cutworms. These species are covered in chapter 6 with other insects found associated with soil and roots. In addition, there are many species of “climbing cutworms” that do not restrict feeding to the soil surface and that climb plants, usually at night, to chew leaves, buds, and developing fruit. Those that have a habit of feeding aboveground and also becoming abundant at times and occurring in large migrations may also be known as “armyworms.” Adult stages of cutworms and armyworms are moderately large gray or brown moths, usually with indistinct markings.

Variegated Cutworm (Peridroma saucia)1 hosts Variegated cutworm has arguably the widest range of host plants of any caterpillar that occurs in North America; it is damaging to vegetables, many fruit crops, and field crops. Potato, pea, cabbage, lettuce, mint, and tomato are among the garden crops most commonly damaged. Damage Larvae feed on foliage, buds, and shoots and may cut seedlings. Existing fruit may be tunneled. Potato tubers are gouged by feeding larvae. Distribution Variegated cutworm is a species with very wide host range and can be found throughout North America. Appearance Larvae are among the most recognizable of the cutworms, with a series of pale yellow spots on the back of most segments. A dark “W” mark is usually present on the eighth abdominal segment. Adult moths are ashy or light dirty brown with some dark brown mottling. Life History and Habits Variegated cutworm usually winters as a pupa in the soil, but it may be active year­round in extreme southern areas. Adults are strong fliers and may disperse over wide areas. Eggs are laid in batches of 60 or more on stems and leaves or on nearby inanimate objects such as fences and buildings. Larvae feed primarily at night but may be active during the day on occasion. The entire life cycle can be completed in 6–8 weeks and 2 generations are usually produced annually in the northern U.S. In warmer areas of the south, as many as 4 generations are sometimes reported.

Fall Armyworm (Spodoptera frugiperda)1 hosts Primarily grasses, including corn and bermudagrass. Legumes, some vegetables, fruit trees, and flowers are occasionally damaged. Damage In young corn, larvae tunnel into the whorl and shred the emerging leaves. As ears develop, they tunnel into ears, often entering from the sides as well as the tips. When turfgrass is chewed it has a ragged appearance. Distribution Fall armyworm is a tropical species that irregularly survives winter in the U.S., even in the Gulf States. It is highly dispersive, and migrations from Mexico and Central America occur annually, frequently reaching as far north as New England by early summer. Appearance Adults are similar to other cutworms, with a wingspan of about 1½ inches and dark gray forewings mottled with lighter and darker patches and crossing lines. There is a noticeable whitish spot near the wing tip. Larvae range from light tan to green or nearly black. A prominent inverted white Y on the head distinguishes this species from armyworm and some other cutworms. 94

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A. Variegated cutworm in tomato fruit. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Variegated cutworm. DAVID SHETLAR

C. Variegated cutworm pupa. DAVID SHETLAR

I

D. Variegated cutworm adult. DAVID SHETLAR

E. Variegated cutworm egg mass. DAVID SHETLAR

F. Fall armyworm egg mass at hatch. DAVID SHETLAR

G. Fall armyworm egg mass on bentgrass. DAVID SHETLAR

H. Fall armyworm. DAVID SHETLAR

I. Fall armyworm, adult. DAVID SHETLAR

Insects that chew on Leaves and needLes

cLIMBInG cUtwoRMs and aRMY woRMs Life History and Habits Annual activity begins in spring when adult migrations reach the U.S. or when overwintering pupae emerge as adults in southern states. Eggs are laid at night in masses of about 400 eggs, covered with hairs of the moth. Egg masses are laid directly on corn and other plants, but infestations of turfgrass often result from larvae dispersing from eggs laid on inanimate objects such as goal posts, flagging, and the underside of tree leaves. Younger stages often feed on only a single side of the leaf blade, leaving a transparent outer surface. Older larvae are more general feeders and consume entire areas of the leaf. When populations are abundant and food becomes limiting, fall armyworm larvae may move in masses in an armyworm­like manner. Larval development takes about 2–3 weeks to complete, and pupation occurs in the soil in a loose cocoon. Three or four generations per year are typical for the southern U.S. and one or two in the north.

Beet Armyworm (Spodoptera exigua)1 hosts A wide range of plants are eaten by beet armyworm , including vegetables such as lettuce, most crucifer crops, beet, tomato, bean, onion, and asparagus. Many herbaceous ornamentals and weeds are also hosts. Damage Caterpillars feed primarily on foliage but may chew into stems and sometimes upper roots. Beet armyworm may bore into the heada of leafy vegetables, characteristically entering plants from the base. Distribution Beet armyworm is found primarily in the southern U.S., where it can successfully survive winter conditions. It is a highly dispersive species that may sometimes migrate into more northern areas in large numbers, creating occasional outbreaks in more northern areas. Appearance Caterpillars are smooth and light olive green. Dark lateral stripes and fine wavy light stripes along the back are the primary markings. Adults have slightly mottled grayish brown forewings with a pale spot in the middle of the front margin. Life History and Habits Winter is usually spent as a pupa in a shallow earthen cell. Adults emerge in spring, and females lay eggs in masses. Approximately 80 eggs are laid in a mass, which is then covered with hairs, giving it a cottony appearance. Early­instar larvae feed as a group and skeletonize the leaves. Older larvae disperse and feed singly, often tunneling into plant parts. Beet armyworm larvae can be quite mobile and frequently move between plants. The life cycle can be completed in about a month under normal summer conditions, and four generations are commonly produced annually over much of the range.

Other Climbing Cutworms and Armyworms Yellowstriped armyworm (Spodoptera ornithogalli) and western yellowstriped armyworm (S. praefica) have a wide host range including most vegetables, some flowers, and occasionally even turfgasses. They are sometimes important defoliators of commercial vegetable crops but rarely are serious pests in gardens, with caterpillars often preferring various weeds, including grasses such as foxtails. Yellowstriped armyworm is found over a broad area of the eastern U.S. east of the Rockies but also extends southwest into southern California. Western yellowstriped cutworm predominates in northern California and the Pacific Northwest. Life cycles of both species are similar to that of the beet armyworm. Southern armyworm (S. eridania) is a common pest of vegetables in the southeastern states. The larvae are generally dark with prominent yellow stripes running the length of the body. Young larvae feed as a group, skeletonizing leaves. As they get older, they become solitary and may enter fruit, exposed tubers, and stems as well as feed on leaves. Four generations are thought to occur in Florida, with activity from March through October. 96

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A. Fall armyworm damage to bermudagrass. DAVID SHETLAR

b. Beet armyworm larva. JOHN CAPINERA, UNIVERSITY OF FLORIDA

C. Beet armyworm egg mass. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

D. Beet armyworm larva. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

E. Yellowstriped armyworm. DAVID SHETLAR

F. Yellowstriped armyworm,

adult.

DAVID SHETLAR

G. Southern armyworm. RONALD SMITH, AUBURN UNIVERSITY, BUGWOOD.ORG

Insects that chew on Leaves and needLes

cLIMBInG cUtwoRMs and aRMY woRMs Armyworm (Mythimna unipuncta),1 sometimes known as the “true armyworm,” is primarily a grass feeder. The adult moths are uniformly brown, distinguished by a small white dot in the center of the forewing. The moth is sometimes referred to as the “white­speck” due to this marking. They are strong fliers and may migrate long distances. Eggs are laid in masses of more than 100 eggs, usually among dense grasses or other moist vegetation. Grasses are highly preferred, and armyworm is primarily a pest of small grains and, less commonly, turfgrasses. However, it feeds on a wide variety of plants and can damage most vegetable crops. When populations are abundant and available food has been consumed, armyworm caterpillars will migrate in large masses to seek new food sources. Armyworm occurs throughout much of North America but is most common east of the Rocky Mountains. The overwintering stage can be variable; both pupae (northern locations) and larvae (southern states) are reported. Four or five generations are produced annually. Outbreaks can be explosive but rapidly decline because of natural controls. Bertha armyworm (Mamestra configurata)1 is primarily a pest in the Prairie Provinces and British Columbia but is occasionally damaging in the Pacific Northwest and northern High Plains. It has a wide host range but feeds primarily on crucifers and beet family plants, with wild mustard and lambsquarter being important weed hosts. Other commonly damaged plants include potato, beans, and several garden flowers such as hollyhock, petunia, and zinnia. Moths emerge in June and July, and females lay eggs as masses on the underside of leaves. Young stages are greenish with narrow pale stripes on the back and sides. Later stages become darker, sometimes brownish. Feeding occurs at night, when the larvae work as “climbing cutworms,” chewing leaves and flower buds. Pupation occurs in the soil, in a cell often dug to a depth of 1 foot or more. The name spotted cutworm is applied to two species of similar habit, Xestia c-nigrum1 and X. dolosa. The caterpillars are grayish brown or green with a series of distinct paired black triangular wedges along the back. Spotted cutworms climb foliage and have been reported damaging fruit buds as well as a wide variety of vegetables and garden plants, particularly in summer. Winter is spent in the larval stage, with pupation in spring. One generaton per year is normally produced in Canada and the northern states and up to three generations may develop in southern areas. Western bean cutworm (Loxagrotis albicosta)1 is primarily an insect of the western Great Plains. Although beans and tomato are occasionally damaged, it most commonly damages corn. Larvae chew leaves and tunnel ears during late summer. Eggs are laid as masses in late July and August, and larvae may occur in small groups, unlike more solitary cutworms such as corn earworm. After feeding is completed, larvae tunnel into the soil to pupate. One generation is produced annually. Granulate cutworm (Agrotis subterranea)1 is the most important cutworm pest of vegetables in the Gulf States and ranges northward to Ohio. Adult females lay eggs directly on foliage, and the young larvae skeletonize leaves as they feed. Older larvae move to the soil during day and feed at night, becoming generalized leaf feeders. Granulate cutworm may cut seedlings, consume leaves, and incidentally damage fruit of a wide range of vegetable crops. It may reproduce continually in southern areas, with all stages present year­round. In Tennessee there are three generations, with winter spent as a pupa. Zebra caterpillar (Melanchra picta)1 is one of the most distinctive garden caterpillars. Black, white, and yellow stripes run the length of the body, and numerous small, alternating black and yellow bands run across the body. This species may feed on several vegetables as well as some flowers but is primarily damaging only to cabbage and related plants. Winter is spent as a pupa in the soil. The adults are chocolate brown moths that lay eggs as masses. The newly hatched larvae feed as a group, skeletonizing the leaf surface. Older larvae disperse and feed more generally on leaves and flowers. Two generations are normally completed annually. 98

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A. Armyworm. DAVID SHETLAR

B. Armyworm, adult. WHITNEY CRANSHAW

C. Zebra caterpillar. WHITNEY CRANSHAW

D. Adult of the zebra

caterpillar.

THE KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Western bean cutworm. JIM KALISCH, UNIVERSITY OF NEBRASKA

Insects that chew on Leaves and needLes

cLIMBInG cUtwoRMs and aRMY woRMs Eightspotted forester (Alypia octomaculata)1 feeds on grape and Virginia creeper east of the Rockies. The common name refers to the features of the adult, a velvety black moth with paired light markings on each of the four wings. Moths fly during the day and can often be seen visiting flowers for nectar. The caterpillars are white or pale bluish, well patterned with rows of black spotting, orange banding along the side, and a rounded hump on the hind end. They chew leaves from early June through August. Apparently two generations are produced, with adults most common in May and early August. Winter is spent as a pupa in a cocoon in the soil. Okra caterpillar (Anomis erosa)1 feeds on leaves of okra and related mallow family plants in the southeastern U.S. Although common, it is rarely abundant enough to cause serious injury. The caterpillars walk in a manner similar to loopers, but they do possess a fourth, albeit small, pair of prolegs. Okra caterpillars are yellowish green or green and have a dark stripe down the back. One of the few chewing insects that damage ferns is Florida fern caterpillar (Callopistria floridensis),1 native to many southeastern and Gulf States. The caterpillars have two color phases, either pale green or velvety black, and are marked with two wavy light stripes. Velvetbean caterpillar (Anticarsia gemmatalis) is the most common caterpillar that feeds on leaves of soybean in the southeastern states. It is native to tropical America and occurs in the U.S. as an annual migrant. Other legumes are hosts of this insect, including kudzu, velvetbean, black locust, hairy indigo, and white sweetclover. The large yellow underwing (Noctua pronuba)1 is a European species that has rapidly colonized large areas of the continent. The adult insect is most commonly observed, and its common name is appropriately descriptive as the moths have a wingspan that may exceed 2 inches. Underneath the brown, mottled forewings are bright yellow hindwings, margined with black. The caterpillars feed on a wide variety of plants commonly grown in gardens and may cause damage in spring to plants both near ground level and on aboveground leaves and buds. It is also the adult stage of the underwing moths (Catocala spp.)2 that is most likely to be seen, often near outdoor lights. These are large moths, typically with wingspans of 2–3 inches. The front wings are grayish, often with wavy patterns, which allow them to blend well with bark of trees. However, the underwings are very brightly colored and patterned, and these may be suddenly flashed when the moth is disturbed. The caterpillars are sometimes called “false loopers,” though they have the full complement of five prolegs. These caterpillars are rarely observed as they blend in well on twigs and small branches. More than 100 species of underwing moths occur in the U.S. and Canada, and the caterpillars of almost all species chew leaves of various trees and shrubs. Oaks, hickory, walnut, birch and beech are among the most common host plants.  Lepidoptera: Noctuidae

1

A. Eightspotted forester, adult.

E. Scarlet underwing moth, Catocala coccinea.

JOHNNY N. DELL, BUGWOOD.ORG

WHITNEY CRANSHAW

B. Eightspotted forester caterpillar.

F. Florida fern caterpillars.

JOHNNY N. DELL, BUGWOOD.ORG

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION, BUGWOOD.ORG

C. Larva of the large yellow underwing.

G. Caterpillar of the penitent underwing, Catocala piatrix.

DAVID SHETLAR

WHITNEY CRANSHAW

D. Velvetbean caterpillar. CLEMSON UNIVERSITY - USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD. ORG

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Insects that chew on Leaves and needLes

LOOPERS Many insects described as “loopers” are members of the cutworm subfamily Plusiinae. These are characterized by having only three pair of prolegs on the abdomen, versus five pairs found among most other members of the order. This causes them to walk in a looping fashion, somewhat like the inchworms (page 104), the other common caterpillar family that has a reduced number of prolegs (two pairs).

Cabbage Looper (Trichoplusia ni)1 hosts Despite its name, cabbage looper is not limited to mustard family plants but may also damage plants as diverse as potato, tomato, pea, lettuce, spinach, nasturtium, and carnation. It is sometimes found as a greenhouse pest on various ornamentals. Damage Larvae chew leaves of various plants, occasionally causing serious defoliation. Late instars tend to tunnel into heads of cabbage, lettuce, and other plants, causing additional injury. Distribution Throughout North America, common. Cabbage looper thrives best in warmer climates and survives poorly following winters in areas with extended freezing temperatures. Adults, however, are strong fliers and annually migrate long distances. Appearance Caterpillars are pale green, darkening somewhat as they get older. Faint white stripes run the length of the body. Adults are of moderate size (wingspan about 1½ inches) with mottled gray or brown forewings and a distinctive silvery white U­mark with a single spot below. Life History and Habits Eggs are hemispherical and glued singly to foliage, often in small groups. They hatch in a few days, and the first­stage larvae are creamy colored. They go through a series of molts as they develop, becoming full grown in about 3 weeks. Young larvae typically feed on outer leaves, producing windowpaning patterns on thick­leaved plants such as cabbage. Late stages feed more generally and tend to tunnel into heads. Pupation occurs on or in the nearby vicinity of host plants in a loose cocoon, and the pupal stage lasts 1–2 weeks. The number of generations produced annually is highly variable, and during the growing season generations greatly overlap and become indistinct.

Other Common Garden Loopers Celery looper (Anagrapha falcifera)1 is found throughout most of North America and feeds on a wide range of broadleaf plants; however, it is rarely abundant enough to cause serious injury to gardens. Pea, lettuce, celery, and beet are among the common hosts. Alfalfa looper (Autographa californica)1 is a western species particularly abundant in the Pacific States. It develops on a wide range of vegetables and even some fruits but is most damaging to lettuce, beans, and cabbage family crops. Two or three generations may be completed annually, with winter spent as a pupa in a loose cocoon. Plantain looper (A. precationis) is an eastern species. It feeds on a wide variety of weeds and is rarely damaging to gardens but may occur on some vegetables (bean, cabbage, pea, parsnip) and several ornamental plants (hollyhock, sunflower). Larvae can be distinguished from other loopers by the presence of three thin light stripes on each side of the back and a white stripe along the side. Winter apparently is spent as a larva, with pupation in spring. Two or three generations may occur annually. 102

B

A C

D E

F

G

A. Late-instar cabbage looper caterpillar. WHITNEY CRANSHAW

B. Cabbage looper egg. WHITNEY CRANSHAW

C. Cabbage looper adult feeding at flower. WHITNEY CRANSHAW

D. Early-instar cabbage looper after molt. WHITNEY CRANSHAW

E. Cabbage looper pupa within a loose

cocoon.

WHITNEY CRANSHAW

F. Alfalfa looper. JOHN CAPINERA, UNIVERSITY OF FLORIDA

G. Alfalfa looper adult. WHITNEY CRANSHAW

Insects that chew on Leaves and needLes

LooPeRs, and canKeRwoRMs, InchwoRMs, and sPanwoRMs Soybean looper (Pseudoplusia includens)1 occurs primarily in the southern states, where it may feed on leaves of many plants. In addition to tomato and some other vegetables, it commonly damages foliage of many flowers, including aster, begonia, geranium, chrysanthemum, and poinsettia. Soybean looper may breed continually in extreme southern areas, producing up to five generations annually. Two generations are more commonly reported from the more northern areas where it occurs. Two closely related species, the forage looper (Caenurgina erechtea)2 and clover looper (C. crassiuscula), are most likely to be encountered in turfgrass. The caterpillars most often develop on grasses and clovers, although they may also feed on ragweed and lupines. Larval damage is insignificant, but presence of the adults settling on lawns may cause concern. Striped grass looper (Mocis latipes)2 is a periodic turfgrass pest in the southern states from Texas across to Georgia and Florida. Bahiagrass, bermudagrass, and St. Augustinegrass are preferred turfgrass hosts and it feeds on several grasses, including corn.  Lepidoptera: Noctuidae; 2 Lepidoptera: Erebidae

1

CANKERWORMS, INCHWORMS, AND SPANWORMS Cankerworms, inchworms, and spanworms (Geometridae) develop as slender caterpillars marked by the absence of all but two (rarely three) pairs of prolegs. This causes them to walk in an unusual manner, in a series of loops and extensions of the body. Inchworms or measuring worms are general terms applied to the larvae, whereas adults are known as geometers. Adults of most species are slender­bodied moths with broad wings of about 1 inch in length. Both the hind­ and forewing are usually patterned similarly, and they may be held upright or flat to the sides of the body. This is a large family of insects with more than 1,400 North American species, a handful of which may noticeably occur on shade trees and shrubs in yards and gardens.

Fall Cankerworm (Alsophila pometaria)1 hosts A wide range, including ash, basswood, beech, boxelder, black cherry, elm, red and sugar maples, and red and white oaks. Damage Larvae chew leaves, occasionally causing significant defoliation. During outbreaks there are minor nuisance issues involving the excreted droppings and numerous larvae that spin down from trees on silk threads. Distribution Widely distributed through southern Canada to Alberta and in the U.S. from North Carolina west to Colorado. Isolated populations are reported from Utah and California. Appearance Larvae vary from light green to dark brownish green and are about 1 inch when full grown. The light green form has white lines along the body; dark forms, which predominate during outbreaks, have a broad black stripe on the back. Unlike most inchworms, fall cankerworm has three pairs of prolegs because of the presence of a very small pair on the fifth segment. Male moths are brownish gray with a wingspan slightly greater than 1 inch. Females are wingless and brownish gray.

104

A C

B

A. Soybean looper. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

B. Forage looper, adult. WHITNEY CRANSHAW

D

C. Clover looper. TOM MURRAY

D. Forage looper. TOM MURRAY

E. Grass looper.

E

DAVID SHETLAR

F. Adult of the grass looper. DAVID SHETLAR

F G H

G. Fall cankerworm, green form. WHITNEY CRANSHAW

H. Fall cankerworm, dark form. DAVID SHETLAR

I. Mating pair of fall

cankerworms. DAVID SHETLAR

J. Fall cankerworm female

laying eggs. DAVID SHETLAR

K. Fall cankerworm larva

spinning down from tree. DAVID SHETLAR

I

J

K

Insects that chew on Leaves and needLes

canKeRwoRMs, InchwoRMs, and sPanwoRMs Life History and Habits Most often fall cankerworm winters as eggs in a mass glued to small twigs. Eggs hatch in late April and early May. Young larvae feed on the lower leaf surface and produce skeletonizing wounds. As they get older, they feed in a more general manner and consume all of the leaf except the main veins. When full grown they spin down from the trees, enter the soil, and pupate in a cocoon. Adults usually emerge after a hard freeze in fall. The flightless females climb the trees and, after mating, lay masses of about 100 eggs in a band around twigs. Occasionally emergence occurs in early spring, particularly in northern areas of the range.

Other Cankerworms, Inchworms, and Spanworms Spring cankerworm (Paleacrita vernata)1 often occurs in co­infestations with fall cankerworm and shares much of its broad range of host plants. Caterpillars are green to reddish brown, have a single yellowish stripe on each side, and lack the small third pair of prolegs of fall cankerworm. Spring cankerworm adults emerge in late winter, during warm spells in February and March. Females are flightless and climb trunks to lay eggs in masses under bark flakes and in trunk crevices. Peak feeding by larvae occurs in late spring, after which the larvae spin to the ground to pupate. Elm spanworm (Ennomos subsignaria)1 feeds on elm, hickory, ash, oak, basswood, and birch and sometimes appears in large outbreak numbers similar to and coincident with cankerworms. Larvae may vary in color from slate black to light green, with darker forms predominating when populations are high. When full grown they usually pupate in a cocoon attached to the tree. Adults of both sexes are winged and nearly pure white. Females lay eggs in masses on twigs and small branches during midsummer. Linden looper (Erannis tiliaria)1 is a common caterpillar of shade trees throughout much of the northern half of the U.S. and Canada, east of the Rockies. It has a broad host range, including basswood, apple, maple, and oak. Females are wingless and lay eggs in fall, in small clusters under loose bark. One generation is produced per year. Winter moth (Operophtera brumata)1 is a European species that was separately introduced into both the northwestern states, where it presently occurs in Oregon, Washington, and British Columbia, and the Maritime Provinces, from which it has since spread into large areas of New England. Adults appear over a period of several weeks, from late November through December, and females lay masses of eggs on the trunk and branches of host trees. A wide range of hosts may be used by winter moth, but maple, oak, apple, crabapple, ash, fringetree, and blueberry are most common. Eggs hatch in late March or early April, and the green caterpillars first feed by tunneling into the unopened buds, including the flower buds of blueberries. After buds open the green­colored caterpillars feed more generally on the emerging leaves and can cause extensive defoliation of plants. They become full grown in late May and early June then drop to the soil where they pupate. Barberry looper (Coryphista meadii)1 caterpillars feed on leaves of mahonia and barberry, sometimes seriously defoliating the plants. Winter is spent as a pupa in the ground, and the adults lay eggs in masses of about 100 on twigs in early spring. Larvae first skeletonize leaves and later consume the entire tough leaf except the larger veins. Three generations may be produced during a growing season. Holly looper (Thysanopyga intractata)1 is found in the eastern U.S. wherever its primary host plant, American holly, is present. It is a highly migratory insect, and overwintering populations in the Gulf States may disperse long distances by midsummer. Caterpillars are light green. Typical injury to holly appears as deep notching cuts along the leaf margins. 106

B C

D

A e

A. Spring cankerworm. DAVID SHETLAR

B. Elm spanworm. TOM MURRAY

C. Linden looper larva. BOB HAMMON, COLORADO STATE UNIVERSITY

D. Linden looper larvae just after egg

hatch.

BOB HAMMON, COLORADO STATE UNIVERSITY

E. Adult male of the winter moth.

F

G

ROBERT CHILDS, UNIVERSITY OF MASSACHUSETTS, BUGWOOD.ORG

F. Caterpillar of the winter moth. TOM MURRAY

G. Linden looper adult female moth. BOB HAMMON, COLORADO STATE UNIVERSITY

H. Linden looper adult male. BOB HAMMON, COLORADO STATE UNIVERSITY

I. Barberry looper. TOM MURRAY

H

I

Insects that chew on Leaves and needLes

canKeRwoRMs, InchwoRMs, and sPanwoRMs Currant spanworm (Speranza ribearia)1 is generally distributed in the northern U.S. and southern Canada, east of the Rockies. Currants and gooseberry (Ribes spp.) are hosts. Larvae first feed on leaf tips and then become general defoliators. They are primarily white with yellow stripes that run along the back and sides. Numerous dark spots are also present, making larvae superficially resemble larvae of the more common currant sawfly. Dull yellow­gray eggs that subsequently overwinter are laid in early summer on branches, usually in the lower canopy. Bruce spanworm (Operopthtera bruceata)1 occurs throughout southern Canada and the upper midwestern and northeastern states. It develops on a wide variety of shade and forest trees, including sugar maple, aspen, willow, and beech. It sometimes damages blueberry and raspberry as well. Overwintering eggs hatch in early spring, and most larval feeding occurs during May and June. Larvae vary from greenish to dark brown and have three light stripes. They may feed in small groups and sometimes loosely web leaves together as they feed. Pupation occurs in a cocoon around the base of a plant. Adults emerge in fall and mate, and females lay numerous single eggs in various crevices on the plant. Females have rudimentary wings but are incapable of flight. The snowbush spanworm (Melanchroia chephise) feeds on leaves of snowbush (Breynia nivosa) and a few other plants, including Otaheite gooseberry, white sapote, and snow­on­the­mountain. The caterpillars are brightly colored with black banding. The adult moths have uniformly dark gray wings, tipped with white. This species occurs in the southeastern U.S., from Oklahoma to Florida. Omnivorous loopers (Sabulodes aegrotata, S. caberata)1 are Pacific Coast species that feed on a wide range of trees and shrubs, including acacia, boxelder, California buckeye, chestnut, citrus, elm, eucalyptus, fruit trees, ginkgo, magnolia, maple, pepper tree, and willow. Larvae feed in leaves that they tie together with silk. Early feeding appears primarily as skeletonizing but later becomes more generalized. Pupation also usually occurs in the rolled leaves. As many as five generations may be produced in a year. Bougainvillea is a common host for the bougainvillea looper (Disclisioprocta stellata), which occurs in Hawaii, California, and across the southern U.S. Feeding injuries produce a ragged scalloping along leaf edges. Other garden plants that may also be eaten by this insect include amaranthus and four o’clocks. Filament bearer (Nematocampa limbata)1 is an eastern species that has a rather bizarre appearance, with long filaments on the second and third abdominal segments. It has a wide host range that includes hemlock and fir as well as various deciduous trees such as maple, oak, pin cherry, buckeye, and apple. Horned spanworm (N. resistaria),1 a minor pest of cranberry in the northeastern U.S., possesses similar fleshy filaments on the abdomen. Several Lambdina1 species affect shade trees. Hemlock looper (L. fiscellaria fiscellaria) is an eastern species that has produced historical forest outbreaks, particularly involving Canada hemlock. Several other trees may also host this insect, including balsam fir and spruce. A subspecies, sometimes known as the “western hemlock looper” (L. fiscellaria lugubrosa) is present from Oregon to Alaska, where western hemlock is the primary host. Eastern pine looper (L. pellucidaria) has also occurred in outbreaks among native pines. In the western states, oak looper (L. vitraria) can be common on oak, particularly Gambel oak. Almost all the Lambdina species overwinter as eggs on trunks and among protective debris. Larval feeding occurs in spring, and one generation is produced annually. On occasion populations may increase dramatically, producing an outbreak, but numerous natural enemies act on these insects so that damaging populations rarely occur in consecutive years.  Lepidoptera: Geometridae

1

108

A

B

C D

E

F

A. Bruce spanworm. E. BRADFORD WALKER, VERMONT DEPARTMENT OF FORESTS, PARKS AND RECREATION, BUGWOOD.ORG

B. Snowbush spanworm larvae. DOUG CALDWELL, UNIVERSITY OF FLORIDA

C. Adult of the snowbush spanworm. DOUG CALDWELL, UNIVERSITY OF FLORIDA

D. Bougainvillea loopers. DAVID ROSEN, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

E. Larva and defoliation caused by oak

looper.

USDA FOREST SERVICE-OGDEN, BUGWOOD.ORG

F. Hemlock looper. CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

Insects that chew on Leaves and needLes

DIAMONDBACK MOTH (Plutella xylostella)1 hosts A wide variety of plants in the mustard family, including cabbage, broccoli, mustard, watercress, and many related weeds. Damage Caterpillars feed on leaves. Although very small (individual caterpillars consume far less than do the larger cabbage looper or imported cabbageworm), they can be extremely abundant. Diamondback moth has increased in importance because of its ability to develop resistance to many commonly used insecticides. Distribution Throughout North America. Appearance Larvae are small caterpillars, less than ½ inch when full grown, and are pale green with the hind pair of prolegs conspicuously protruding. Larvae wriggle vigorously and drop from plants when disturbed. Adults have generally gray wings which, when folded over the body, show a series of white diamond patterns on the back. Life History and Habits In northern areas, diamondback moths winter as pupae, with adults emerging and becoming active in early spring. In southern areas, development may be continuous. Eggs are laid singly or in small groups on leaves of various mustard family plants. Young larvae typically feed on the underside of leaves and produce windowpane injuries. Older larvae feed more generally. Pupation occurs in a loose cocoon, usually attached to outer leaves. Three to four generations are typically produced annually in northern areas, with more than a dozen possible in the south.  Lepidoptera: Plutellidae

1

SKELETONIZERS The term “skeletonizer” is broadly applied to caterpillars of several moth families that feed between veins of leaves, producing skeletonized appearance though there are beetles and sawflies that skeletonize leaves. Apple and thorn skeletonizer (Choreutis pariana)1 is common in much of the northern U.S. and southern Canada, sometimes occurring in populations that fluctuate greatly in abundance between seasons. It is associated primarily with fruit trees but has a wide host range that includes crabapple, apple, birch, cherry, hawthorn, willow, and mountain­ash. The overwintering moths lay eggs shortly after bud break. Larvae first feed on the underside of leaves under a covering of silk. They later migrate to the upper leaf surface and construct a new shelter by tying adjacent leaves together. During the warm season, the life cycle can be completed in a month, and up to four generations per year can be produced. Oak ribbed skeletonizer (Bucculatrix albertiella)2 occurs in the Pacific States. Young larvae feed as leafminers of oak leaves. As they get older, they skeletonize the surface. They produce characteristic cocoons that are strongly ribbed. Two generations are produced in Washington. Oak skeletonizer (B. ainsliella) is particularly common around the Great Lakes but ranges from New England to Mississippi. It feeds on oak and chestnut. Adults appear in late May and lay eggs on leaves. Initial feeding occurs as small mines, and later feeding skeletonizes the underside of leaves. Small patches of webbing are produced whenever oak skeletonizers molt, and they also pupate in white, ribbed cocoons.

110

A

B A. Diamondback moth.

C D

DAVID CAPPAERT, BUGWOOD.ORG

B. Diamondback moth

caterpillar.

ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

C. Diamondback moth injury

to broccoli.

WHITNEY CRANSHAW

D. Diamondback moth pupa,

within a loose cocoon. WHITNEY CRANSHAW

E

F

G

H

J

I

E. Damage by apple and thorn skeletonizer. ROBIN ROSETTA, OREGON STATE UNIVERSITY

F. Apple and thorn skeletonizer. ERIC LAGASA, WASHINGTON STATE DEPARTMENT OF AGRICULTURE, BUGWOOD.ORG

G. Adult of the oak skeletonizer. DAVID SHETLAR

H. Damage by oak skeletonizer. DAVID SHETLAR

I. Pupae of the oak skeletonizer. JAMES SOLOMON, USDA-FOREST SERVICE, BUGWOOD.ORG

J. Oak skeletonizer caterpillar. G. KEITH DOUCE, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

Insects that chew on Leaves and needLes

sKeLetonIZeRs Birch skeletonizer (Bucculatrix canadensisella) feeds on birch, particularly paper birch. It pupates off the tree, spinning down when full grown and producing a dark cocoon in leaf litter and other debris. Apple bucculatrix (B. pomifoliella) occurs in the northeastern U.S. and southeastern Canada, where it feeds on hawthorn, apple, black cherry, and serviceberry. Hollyhock leaf skeletonizer (B. thurnberiella) skeletonizes hollyhock and malva in California. Western grapeleaf skeletonizer (Harrisina metallica)3 is found west of the Rockies, where it develops on wild and cultivated grapes, Virginia creeper, and Boston ivy. Some fruit trees are occasionally infested. Adults are unusual bluish black or greenish black moths with a wingspan over 1 inch; they first emerge from late April through mid­May. Females lay eggs in clustered groups on the underside of leaves, usually in shaded areas of the vines. The larvae feed together, often side by side, during most of their development, skeletonizing leaves from the underside. As the larvae get older, extensive defoliation can rapidly occur. The larvae are strikingly colored insects with brightly colored bands of yellow, white, blue, and black across the body. They are also covered with moderate­sized hairs that can be very irritating to people who are sensitive to them. In central California three generations are produced annually. Winter is spent as a pupa in a cocoon, often attached to loose bark of the vines. In the eastern states, grapeleaf skeletonizer (H. americana) is present and similarly feeds on grape and Virginia creeper. Most of its habits parallel those of western grapeleaf skeletonizer. Larvae are yellowish with black banding and usually feed gregariously, although late­stage larvae chew holes in leaves. One generation is typically completed, sometimes a second. Pryeria sinica (“euonymus leaf notcher”)3 is a newly established species in Virginia and Maryland, with expanding range, that develops on leaves of Euonymus and Celastrus. Young larvae feed as a group and skeletonize but later disperse throughout the plant and cause more generalized defoliation, particularly around leaf edges. Injury occurs in April and May and there is one generation per year. Palm leaf skeletonizer (Homaledra sabalella)4 is an insect native to Florida and areas of the Carribean, which develops on sabal palmettos and occasionally palms, including coconut. The caterpillars feed gregariously, primarily on lower leaf surface, and create a silken tube that becomes mixed with their excreted frass. Larvae of maple trumpet skeletonizer (Calastega aceriella)5 make unusual trumpetlike tubes of silk and incorporate frass that covers their bodies. Adults lay eggs on leaves of sugar and red maples in June and early July, and the larvae develop as skeletonizers feeding between veins of loosely folded leaves. They drop to the ground later in the summer when full grown and pupate in a cocoon. One generation is produced. Maple trumpet skeletonizer occurs in the northeastern U.S. and southeastern Canada.  Lepidoptera: Choreutidae; 2 Lepidoptera: Bucculatricidae; 3 Lepidoptera: Zygaenidae;

1 4

Lepidoptera: Pterolonchidae; 5 Lepidoptera: Tortricidae

112

A

B

C D

E

A. Larva of the birch skeletonizer.

E. Adult of the grapeleaf

DAVID SHETLAR

DAVID CAPPAERT, BUGWOOD.ORG

B. Damage produced by birch skeletonizer.

F. Late-instar larvae of the euonymus leaf notcher.

DAVID SHETLAR

ERIC DAY, VIRGINIA POLYTECHNIC AND STATE UNIVERSITY, BUGWOOD.ORG

C. Grapeleaf skeletonizer

larvae.

JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Western grapeleaf skeletonizer larvae. HAROLD LARSEN, COLORADO STATE UNIVERSITY

F

skeletonizer.

G Skeletonizing damage

by young larvae of the euonymus leaf notcher.

ERIC DAY, VIRGINIA POLYTECHNIC AND STATE UNIVERSITY, BUGWOOD.ORG

G

Insects that chew on Leaves and needLes

BAGWORMS AND CASEBEARERS Bagworms (Psychidae) are unusual caterpillars that develop in a silken case covered with leaf fragments or other debris. Adult females are wingless moths that remain in the case. Adult males, if they are produced, are winged. The term “casebearer” is generally applied to larvae of small moths (Coleophoridae) that produce a parchmentlike case that the caterpillar carries throughout development; however, some other types of caterpillars construct protective cases of silk that in­corporate leaf material and/or frass. Case making, with incorporated frass, also occurs with the larvae of leaf beetles in the genera Neochlamisus and Exema (page 182).

Bagworm (Thyridopteryx ephemeraeformis)1 hosts Juniper, cedar, false cypress, and arborvitae are most commonly infested. Bagworm may feed on a wide variety of other woody plants including black locust, elm, pine, cabbage palmetto, honeylocust, buckeye, sycamore, and willow. Damage Caterpillars chew foliage and during outbreaks can seriously defoliate plants. Swellings on twigs sometimes occur around the site where bags were attached for pupation. Distribution Generally in the eastern U.S. from southern New England to parts of Nebraska and south to Texas and Florida. Appearance Bagworm is a bizarre caterpillar that develops in a silken bag with bits of interwoven twigs and foliage. When full sized, the bag may be 1½ to 2 inches long. Females remain in the bag through all life stages. Males emerge from the bag and are black, daytime­flying moths that resemble small bumble bees with clear wings that span about 1 inch. Life History and Habits Bagworm winters as eggs in the bag of the mother. In most areas eggs remain dormant until late spring, at which time the larvae emerge and disperse, often ballooning on strands of silk. They begin to feed and construct the case almost immediately, first being found on the upper leaf surface, where they feed on surface tissues. Later they migrate to the underside of leaves and feed more generally, expanding the bag as they grow. When full grown they pupate in late summer. Winged males fly in September to mate with females that remain in their bags. One generation is produced annually in most areas; bagworm may reproduce continually in parts of Florida.

114

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C

D E

A. Bagworms cases on juniper. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Female bagworm exposed within case. DAVID SHETLAR

C. Female bagworm, exposed

D. Bagworm larvae leaving case after egg hatch. DAVID SHETLAR

E. Young bagworm,

within case. DAVID SHETLAR

within case and dissected to show egg.

mating with female in bag.

DAVID SHETLAR

DAVID SHETLAR

F. Bagworm adult male,

F

Insects that chew on Leaves and needLes

BaGwoRMs and caseBeaReRs

Other Bagworms In the southern states, ranging from Virginia to Texas, Abbot’s bagworm (Oiketicus abbotii)1 is also present. It feeds on a variety of commonly grown shrubs, including pyracantha, arborvitae, rose, sugarberry, avocado, mesquite, and giant leadtree. It makes a larger and more distinctive bag than does the bagworm. Grass bagworm (Psyche casta)1 produces a case in the form of a small bundle of grass pieces that is usually noticed when attached to a fence post, building siding, or tree trunk. The cases are constructed of silk with ½­ to 1­inch pieces of grass blades attached. The small caterpillars that make these cases do so in the spring and reach maturity by mid­May. The bags are very well hidden in the grass as the pieces are first green, but they turn brown over time. When mature, the caterpillars in their bags crawl up a permanent surface and attach the bag to it. By mid­June, tiny male gray moths emerge. These seek out the non­winged female bags and mate. After mating, the female deposits her eggs within the bag. The caterpillars feed on a wide variety of plants including grasses, lichens, mosses, and other low­growing plants. Snailcase bagworm (Apterona helix),1 sometimes known as garden bagworm, is an odd insect that constructs a coiled case of silk covered with particles of soil and excrement. Larvae have a wide host range that includes broccoli, bean, squash, gypsophila, violet, alfalfa, vetch, rose, apple, pear, ponderosa pine, and Douglas­fir. Snailcase bagworm is found in localized areas throughout the western states and has become established in parts of New York, Pennsylvania, Massachusetts, and Michigan. The introduced insect is easily spread by humans and can be expected to increase its range. Winter is spent as a young larva in the case of the mother bagworm. Larvae emerge in spring to complete development, producing the typical case they carry and remain in throughout life. As they feed, larvae often chew the leaf interior, similar to a leafminer but with the bag remaining on the outside. Injuries result from windowpaning or from skeletonizing. Mature larvae have a migratory habit and move to a vertical surface where they fasten firmly for pupation. Adult females emerge in the case in August and lay eggs. Males are unknown for this species. Two European species of bagworms that feed on lichen and algae are present in some areas of eastern North America, Dahlica triquetrella1 and D. lichenella. Neither is damaging to garden plants, but their cases may attract interest when seen attached to rocks, walls, and other sites where lichen are present. Bits of their food plants and small pieces of soil are often incorporated into the larval cases. 1

 Lepidoptera: Psychidae

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A

B

C D

E

F

A. Grass bagworm, larva. DAVID SHETLAR

B. Grass bagworm, adult

male.

DAVID SHETLAR

C. Snailcase bagworms. WHITNEY CRANSHAW

D. Snailcase bagworms feeding on Canada thistle. WHITNEY CRANSHAW

E. Snailcase bagworm

crawling up wall. WHITNEY CRANSHAW

F. Snailcase bagworms

settled for pupation under eaves of a barn. WHITNEY CRANSHAW

Insects that chew on Leaves and needLes

BaGwoRMs and caseBeaReRs

Casebearers Pistol casebearer (Coleophora malivorella)1 is widespread east of the Rocky Mountains and feeds on leaves and buds of most tree fruits, especially apple, pear, and cherry. Larvae feed and destroy leaf and flower buds early in the season. Later they make shallow mines as they feed on maturing fruit and leaves. Winter is spent as a partially grown larva in the case, which is dirty gray­brown. Larvae move to buds with warm days in spring, and as they grow they continue to enlarge the case with silk mixed with leaf fragments and excrement. The case becomes curved in later stages, somewhat resembling a pistol. Around mid­June the larvae secure the cases to twigs or leaves and pupate. After about 2 weeks, adult moths emerge and lay eggs within a few days of emergence. Eggs are laid on the upper side of leaves. After egg hatch, larvae tunnel to the underside of leaves, form new silk cases, feed until fall, and secure themselves to twigs for winter. Cigar casebearer (Coleophora serratella)1 has a similar life history and overlaps both in its range of hosts and in distribution. Larvae are dark orange with a black head and produce a cigar­shaped case of leaf fragments. Adults are small steel­gray moths with fringed wings and are present in early summer. Elm casebearer (C. ulmifoliella)1 is an eastern U.S. species that makes a small case by folding and cutting the edge of an elm leaf. From within these cases, the larvae mine brown patches between leaf veins of American, red, and slippery elm. Pecan cigar casebearer (C. laticornella) causes similar injury to pecan. The first generation of pecan leaf casebearer (Acrobasis juglandis)2 also damages early­season growth of pecan. Later generations cause little damage to host trees. Older larvae live in grayish, trumpet­shaped cases attached to the undersides of leaflets. Larch casebearer (Coleophora laricella)1 is an introduced species that now occurs throughout the range of native larch and occurs as a pest where larch is used in landscape plantings. Peak injury is caused shortly after bud break when the overwintered larvae resume feeding. They mine individual needles, as deeply as their bodies can extend beyond the case they carry. They become full grown and pupate by late spring in the case constructed of silk and portions of damaged needles. Adults lay eggs in late spring and early summer. Early­stage larvae feed through the summer as needleminers and then create a case in which they winter. The case is located at the base of larch buds and resembles dead needles.  Lepidoptera: Coleophoridae; 2 Lepidoptera: Pyralidae

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A

B

C

F

D

E

H

I

G

A. Case of a cigar casebearer.

D. Adult of the elm casebearer.

WHITNEY CRANSHAW

DAVID SHETLAR

G. Adult larch casebearer. DAVID SHETLAR

B. Elm casebearer.

E. Casebearer pupating on wall.

H. Larch casebearer.

DAVID SHETLAR

WHITNEY CRANSHAW

DAVID SHETLAR

C. Pecan cigar casebearer.

F. Larch casebearer.

I. Pecan leaf casebearer.

H. C. ELLIS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

DAVID SHETLAR

JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

Insects that chew on Leaves and needLes

BaGwoRMs and caseBeaReRs

Caterpillars that Produce Cases of Leaf Fragments Maple leafcutter (Paraclemensia acerifoliella)1 feeds on maple in the northeastern U.S. and southern Canada. Early larvae initiate feeding as leafminers, shortly after new leaves have emerged. Older larvae move outside and fashion a case out of round fragments cut from leaves. When feeding, the larva attaches the case to the leaf surface and feeds as far as it can reach, producing circular holes in the leaves. Feeding is usually completed by late spring, and the larva drops to the ground to pupate and overwinter. Leaf crumpler (Acrobasis indigenella)2 produces a silken shelter tube attached to twigs. The caterpillars feed on leaves of a wide variety of rosaceous plants, including hedge cotoneaster, crabapple, pyracantha, hawthorn, and pear. It occurs in most of North America east of the Mississippi River and in California. Winter is spent as a partially grown larva in the case. Larvae resume feeding in spring and may leave their cases to feed at night, returning with leaf fragments. Pupation occurs in May, and adults lay eggs on leaves a few weeks later, producing a summer generation that is usually most damaging. In most areas two generations are annually produced, but only one may occur in more northern areas. China mark moth (Nymphuliella daeckealis)3 develops on waterlily (Nymphoides, Nymphaea) and is one of several caterpillars adapted to living on aquatic plants. Winter is spent as a partially developed caterpillar within a shelter attached to the stems of plants. In spring when water warms they move to the surface and resume feeding, producing skeletonizing injuries. At all times the larvae live within pieces of cut leaves, a habit leading to the common name “sandwich­man caterpillar.” New pieces are cut as the caterpillars grow, giving waterlily leaves a ragged appearance. These leaf shelters also float, allowing the caterpillars to move among plants. Pupation occurs within the cut leaf shelter and adults subsequently emerge. The insect gets its name from the features of the adult moth, which has white forewings marked with dark gray. Eggs are laid on the surface of leaves. Three generations a year are normally completed in Maryland. Waterlily leafcutter (Elophila obliteralis)3 also cuts leaves to construct a shelter and feeds on several aquatic plants, including waterlily, pondweed, and duckweed. Although damage to plants is usually minor, it has been found to significantly damage Hygrophila, an important invasive aquatic weed in Florida. Lepidoptera: Incurvariidae; 2 Lepidoptera: Pyralidae; 3 Lepidoptera: Crambidae

1 

Maple leafcutter larva exposed from leaf shelter. RONALD S. KELLEY, VERMONT DEPARTMENT OF FORESTS, PARKS AND RECREATION, BUGWOOD.ORG

Injury by leaf crumpler caterpillar. JIM KALISCH, UNIVERSITY OF NEBRASKA

B

A C

D E

F

A. Maple leafcutter injury. RONALD S. KELLEY, VERMONT DEPARTMENT OF FORESTS, PARKS AND RECREATION, BUGWOOD.ORG

B. Leaf crumpler caterpillar in its case. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Leaf crumpler

showing long tube case it produces.

G

JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Adult of the leaf crumpler. JIM KALISCH, UNIVERSITY OF NEBRASKA

H

E. Leaf shelter produced

by larva of the China mark moth. STANTON GILL, UNIVERSITY OF MARYLAND

F. Larva of the China mark moth. STANTON GILL, UNIVERSITY OF MARYLAND

G. Adult of the

waterlily leafcutter. USDA-ARS, BUGWOOD.ORG

H. Waterlily leafcutter. USDA-ARS, BUGWOOD.ORG

Insects that chew on Leaves and needLes

CATERPILLARS THAT PRODUCE SMALL SILKEN SHELTERS Several types of caterpillars use silk to create small shelters among the foliage on which they are feeding. These are often described as being some type of leafroller, leaftier, or webworm and most occur in the families Tortricidae, Crambidae, and Hesperiidae. In general, the term “leafroller” is used for insects that roll the edge of a leaf, and leaftiers web together two or more leaves to produce a shelter. However, these common names are fairly loosely used and may also be applied to insects with habits that combine both behaviors as well as some caterpillars that create a portable leaf case (discussed above). The use of the term “webworm” is even less consistently used and is applied to insects that make discrete silken tube shelters, others that loosely web leaves together, and some that feed in groups and create large silken tents.

Sod Webworms Sod webworm is a general description of a family of caterpillars (Crambidae) that develop exclusively or primarily on grasses and sedges. Larvae of most species produce a silk­lined tube at the base of the plants in which they live. Adults are often described as “lawn moths,” although there are other types of moths that are sometimes common on lawns. A few species (e.g., cranberry girdler) have a subterranean feeding habit and are discussed in chapter 6, insects associated with roots. A typical species found associated with turfgrasses that is widely distributed in the northern U.S. and southern Canada is the larger sod webworm (Pediasia trisecta).1 Larvae develop primarily on bluegrass, but bentgrass, ryegrass, and fescues may be eaten. Early­stage larvae locate within the leaf fold at the base of the plant and feed on the leaf surface. As they get older, they move to the base of the plant and form a silken tube used as a retreat. They emerge at night and clip grass blades that are dragged back to the shelter and consumed. In high populations, the feeding injuries may produce turfgrass areas that appear thin and have a ragged appearance. The silk tunnel often fills with fecal droppings (frass) and leaf fragments, forcing the larvae to initiate a new tunnel. Larval development following egg hatch may take 30–50 days to complete, after which a cocoon is formed in which to pupate. Adults are snout moths with a wingspan of about 1 inch; at rest the wings are slightly folded over the body, giving the moth a tubular body form. During the day they rest on vegetation and become active at dusk. During egg laying the females fly low over the plants, scattering eggs while in flight. Winter is spent in the form of a partially developed larva, protected within a silken shelter, that resumes feeding in early spring. The number of generations produced by P. trisecta varies by location, with three generations reported from New Jersey and Virginia, and only a single generation noted in Washington.

122

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B

C D

A. Sod webworm larva. DAVID SHETLAR

B. Damage produced by sod webworm. DAVID SHETLAR

C. Adult of the larger sod webworm. DAVID SHETLAR

D. Sod webworm larva. DAVID SHETLAR

E. Life stages of a sod webworm. DAVID SHETLAR

E

Insects that chew on Leaves and needLes

cateRPILLaRs that PRodUce sMaLL sILKen sheLteRs About twenty species of sod webworms have been reported to develop in lawns. Most have feeding habits generally similar to those of the larger sod webworm, although there may be differences in the number of generations produced and periods of peak larval activity. Among those developing on cool-season turfgrasses (bluegrasses, ryegrasses, bentgrasses) are: western lawn moth (Tehama bonifatella), bluegrass webworm (Parapediasia teterrella), striped sod webworm (Fissicrambus mutabilis), elegant sod webworm (Microcrambus elegans), vagabond crambus (Agriphila vulgivagella), lesser vagabond crambus (Agriphila ruricolella), yellow crambus (Neodactria luteolellus), corn root webworm (N. calig­ inosellus), Leach’s crambus (Crambus leachellus), Sperry’s lawn moth (C. sperryellus), silverstriped webworm (C. praefectellus), and Thaumatopsis pexellus.1 The most serious sod webworm pest of warm-season turfgrasses in the southern U.S. is tropical sod webworm (Herpetogramma phaeopteralis), which develops year-round on St. Augustinegrass, bermudagrass, and centipedegrass. Peak injury occurs in fall. Larvae of the snowy urola moth (Urola nivalis)1 also develop on grasses, but the adult is somewhat larger and considerably more showy than are most sod webworms. The snowy urola moth can be found over a broad area of the eastern U.S., ranging into parts of Texas and Arizona. Adults of lucerne webworm (Nomophila nearctica)1 can be seen very commonly on lawns and lowgrowing plants. The moths are somewhat larger than sod webworms, with brown wings marked with darker brown streaks and veins. The larvae feed on many types of low-growing plants, including grasses, clovers, sweetclovers, dichondra, and prostrate knotweed.  Lepidoptera: Crambidae

1

Tropical sod webworm larva.

Tropical sod webworm larva.

DAVID SHETLAR

DAVID SHETLAR

124

A

B C D

A. Adult of the bluegrass webworm. DAVID SHETLAR

B. Adult of the vagabond crambus. DAVID SHETLAR

C. Adult of the tropical sod

webworm.

D. Adult of the snowy urola. DAVID SHETLAR

E. Lucerne webworm. DAVID SHETLAR

F. Adult of the Lucerne webworm. DAVID SHETLAR

DAVID SHETLAR

E

F

Insects that chew on Leaves and needLes

cateRPILLaRs that PRodUce sMaLL sILKen sheLteRs

“Garden Webworms” Two closely related species sometimes damaging to gardens are alfalfa webworm (Loxostege cerealis)1 and beet webworm (L. sticticalis). Caterpillars are about ¾ inch when full grown. They are green or yellowish green when young but darken as they get older. Larvae are found in silken tunnels spun among the foliage and wriggle vigorously when disturbed. These insects may occur on a wide range of garden vegetables, including cabbage, beet, carrot, lettuce, and cucumber. They also occur on several weeds, including lambsquarter, pigweed, and dock. Both species are found primarily in western North America. Alfalfa and beet webworms winter as mature larvae in soil. Adults are active in spring and lay eggs in a small mass that looks somewhat like overlapping fish scales. The newly hatched caterpillars make a small silk pad and skeletonize the leaf surface. Older larvae more extensively web together foliage and produce a silken tube where they rest and from which they emerge to feed. Pupation occurs in the upper soil in a silk­lined cell. Two to four generations may occur per year, depending on temperature and location. Garden webworm (Achyra rantalis)1 can be found in the eastern U.S. and parts of California but is primarily damaging in the southern High Plains. It shares many habits with beet and alfalfa webworms and also produces webbing of leaves tied together to form a loose shelter. Young larvae skeletonize, and older stages feed more generally on leaves. Larvae are generally yellow­green with prominent dark spots and a yellowish head. Beans and peas are common hosts. Celery leaftier (Udea rubigalis),1 also known as greenhouse leaftier, is broadly distributed in North America and occurs as both a greenhouse and garden pest. Beets, lettuce, and celery are the most common vegetable hosts. Ornamental plants on which they feed include chrysanthemum, petunia, geranium, coleus, azalea, and begonia. The caterpillars feed on the leaves, silking them together in a manner similar to that of other “garden webworms.” Mature caterpillars are pale green with a narrow, darker green band along the back and whitish bands along each side. Generations can be completed in from 1 to 3 months, depending on temperature. In the northern half of California and the Pacific States, the closely related false celery leaftier (U. profundalis) is present and sometimes similarly damaging. Cabbage webworm (Hellula rogatalis)1 is found throughout the southern U.S., occasionally dispersing into northern states. Larvae develop on cabbage and related crucifers and cause the most damage when older larvae web leaves together that they chew, damaging the growing point. Younger caterpillars act as leafminers and may tunnel main veins, causing tip dieback. Cabbage webworm is yellowish gray with a dark head and usually found in the loose webbing it produces. Cross-striped cabbageworm (Evergestis rimosalis)1 is an occasional pest of collards, Brussels sprouts, and related vegetable plants. It can be found over much of the eastern U.S. but is common only in some of the southeastern states. Caterpillars have a distinctive patterning of thin black and white striping on the back and prominent yellow lines on the sides. Several generations are produced annually; in southern areas, the species can often be active and damaging by early spring. A related species, purplebacked cabbageworm (E. pallidata), is a species of more northern distribution, ranging into eastern Canada. Larvae feed on cabbage family plants and the mature caterpillars are olive green or purple­brown.  Lepidoptera: Crambidae

1

126

B

A

C D E

F

G A. Beet webworm. FRANK PEAIRS, COLORADO STATE UNIVERSITY

B. Alfalfa webworm eggs. JOHN CAPINERA, UNIVERSITY OF FLORIDA

C. Alfalfa webworm. FRANK PEAIRS, COLORADO STATE UNIVERSITY

D. Adult alfalfa webworm. WHITNEY CRANSHAW

E. Garden webworm. ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

F. Adult of the garden webworm. DAVID SHETLAR

G. Cross-striped cabbageworms. DAVID SHETLAR

Insects that chew on Leaves and needLes

FRUITTREE LEAFROLLER

(Archips argyrospila)1

hosts A wide variety of deciduous trees and shrubs, including apple, crabapple, honeylocust, ash, and linden. Damage Larvae first fold over a leaf and chew it, producing skeletonized patches. Older larvae tie together several leaves with silk and their feeding produces a ragged appearance. On fruit trees, incidental feeding on young fruit may occur, inducing fruit abortion or distortion (catfacing). Distribution Throughout most of North America. Appearance Larvae are green with a black head and found in the folded or tied leaves. When disturbed they wriggle vigorously and may escape the shelter by dropping down on a strand of silk. Adults have rusty brown wings with silvery or pale gold patches. Wingspan is about ¾ inch. Life History and Habits Fruittree leafroller spends winter in the egg stage. Eggs are laid in a flat gray­brown mass, typically containing more than 100 eggs, glued to twigs. Egg hatch occurs in early spring shortly after leaves emerge. Young larvae usually feed first around the tips and emerging leaves. Older larvae begin to tie up leaves with webbing and feed inside this shelter. When mature, larvae usually pupate in the rolled leaves but may disperse to bark cracks of the trunk and large branches. Adult moths appear 2 weeks later, mate, and lay the overwintering egg masses. There is one generation per year.

Other Leafrollers, Leaffolders, and Leaftiers Boxelder leafroller (Archips negundana)1 is found throughout most of the northern half of the U.S. and Canada, feeding on leaves of boxelder and, less commonly, honeysuckle and alder. Rose Tortrix (A. rosana), sometimes known as “filbert leafroller,” develops on filbert, apple, pear, hawthorn, cherry, currant, and privet in the northwestern U.S. and western Canada. The life histories of these other Archips species are similar to that of fruittree leafroller. Oak leafroller (A. semiferana) is primarily associated with red oaks in eastern North America and Gambel oak in the Rocky Mountain region. Late­stage larvae often roll leaves but may tie leaves together and produce visible webbing during outbreaks where significant defoliation occurs. Several other caterpillars tie together leaves of oaks, notably the oak webworm (A. fervida) and oak leaftier (Acleris semipurpurana).1 Injury produced by boxelder leafroller. USDA FOREST SERVICE-OGDEN, BUGWOOD.ORG

128

Oak leaftier injury. DAVID SHETLAR

A C

B A. Leaf tying and feeding

on terminal leaves by fruittree leafroller.

D

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

B. Fruittree leafroller larva. JEFF HAHN, UNIVERSITY OF MINNESOTA

C. Adult fruittree leafroller

next to pupal skin.

JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Egg mass of the fruittree leafroller. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

E. Oak leafroller larva

and pupa.

WILLIAM M. CIESLA, FOREST HEALTH MANAGEMENT INTERNATIONAL, BUGWOOD.ORG

F. Oak leafroller adult. WILLIAM M. CIESLA, FOREST HEALTH MANAGEMENT INTERNATIONAL, BUGWOOD.ORG

G. Boxelder leafroller larva. BILL KLEIN, USDA FOREST SERVICE, BUGWOOD.ORG

E

F

G

129

Insects that chew on Leaves and needLes

LeaFRoLLeRs, LeaFFoLdeRs, and LeaFtIeRs In Louisiana and Mississippi, overwintered eggs of baldcypress leafroller (Archips goyerana) hatch at bud break and the young initially feed within the cluster of emerging needles. Older larvae tie together needles and complete their development within this shelter. Baldcypress webworm (Coleotechnites apicitripunctella)2 develops as a needleminer of hemlock and baldcypress. The mined needles are webbed together into a small mat and the larvae spend winter within this shelter. It occurs in the midwestern and northeastern U.S. and parts of southeastern Canada. Mined needles of spruce are tied together in a similar manner by spruce needleminer (Taniva albolineana).4 Eyespotted bud moth (Spilonota ocellana)1 is a pest of tree fruits and caneberries in the Pacific States and British Columbia. Winter is spent as a young larva within a cocoon attached to the bark (hibernaculum). Larvae emerge and begin to feed around bud break in spring, damaging newly opening buds and leaves. They may also tunnel in shoots of apple or cherry, causing twig dieback. By late spring they complete development, usually pupating on the plant. Eggs are laid during midsummer, and larvae active at this time feed on leaves, typically cutting them and rolling them together, fastened with silken thread. Fruit damage occurs when leaves of feeding shelters include fruit, which may then be scarred by feeding larvae. Obliquebanded leafroller (Choristoneura rosaceana)1 is one of the most common leafrollers, found throughout most of North America except in arid areas of the southwestern U.S. It has an extremely wide host range but feeds primarily on azalea and various rosaceous plants, including fruit trees. Damage begins earlier than with some other leafrollers, as winter is spent as a partially grown larva in a protected cocoon (hibernaculum) on the bark, from which it emerges and tunnels into buds during spring. Developing fruit may also be damaged at this time. First­generation adults are present in late spring, and eggs are laid as masses on leaves during June. The summer generation is completed by August. Large aspen tortrix (C. conflictana) is a forest species that feeds on aspen leaves. Larvae may roll the edge of a single leaf or tie together two leaves to produce a feeding shelter.

above: Eyespotted budworm larva. THE KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

below: Mined needles and associated webbing produced by several spruce needleminers. WHITNEY CRANSHAW

Larva of the large aspen tortrix. DAVID SHETLAR

130

A C D

B E

A. Baldcypress webworm. CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

B. Injury produced by baldcypress webworm. DAVID SHETLAR

F

C. Adult baldcypress

webworm.

DAVID SHETLAR

D. Adult and pupal skin of the

obliquebanded leafroller.

JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Obliquebanded leafroller. TODD M. GILLIGAN AND MARC E. EPSTEIN, USDA ITP, BUGWOOD.ORG

F. Adult obliquebanded leafroller. WHITNEY CRANSHAW

G. Leafrolling produced

by large aspen tortrix.

STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

h. Egg mass of the large aspen tortrix. STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

G H

Insects that chew on Leaves and needLes

LeaFRoLLeRs, LeaFFoLdeRs, and LeaFtIeRs Light brown apple moth (Epiphyas postvittana)1 is a species native to Australia that has recently become established in California. It is a generalist in feeding habits, capable of developing on a very wide variety of hosts; however, it is still unclear how serious a pest this will develop into in North America. In Hawaii, where it was earlier introduced, feeding injury is seen to occur largely on noncrop plants, some of which are considered invasive weeds. Redbanded leafroller (Argyotaenia velutinana)1 is an occasional pest of apple orchards in the northeastern and midwestern states. Both the body and head of larvae are uniformly colored green to pale yellow. The larvae live in a loose silken shelter they spin on leaves and among buds and emerging growth. Leaf­feeding injuries are insignificant, but serious fruit injury is caused when developing fruit is incorporated into the webbing and chewed. Young fruits on which first­generation larvae feed often abort or develop deep gouging wounds. Injuries inflicted by the summer generation produce more superficial fruit scarring. Orange tortrix (A. citrana) is a western species that ties together and feeds on the leaves of tree fruits, citrus, willow, oak, goldenrod, geranium, begonia, black walnut, and many other plants. It usually does little damage, but citrus might be damaged when larvae incidentally chew into the peel of fruit tied among the leaves of the feeding shelter. A minor but commonly observed pest of eastern white pine is pine tube moth (A. pinatubana), which forms shelters of 5–20 needles tied together with silk into a tube. It chews the needles until they are about 1 inch long and then abandons the shelter to form a new one. Two generations occur per year in Pennsylvania, with adults emerging in early to mid­April and the second­generation adults present in July. Blackheaded fireworm (Rhopobota naevana),1 sometimes known as holly bud moth, is a common insect in much of North America. Young larvae of the first generation feed on the opening buds of apple, cherry, blueberry, holly, and other woody ornamentals. Later stages act as leafrollers, tying together leaves in which they feed. Two generations occur, with moths from the second generation present in June in North Carolina. The wintering stage consists of eggs laid on the host plant. Cherry bark tortrix (Enarmonia formosana)1 may develop on most tree fruits and is presently found in parts of Washington and British Columbia. Larvae feed primarily on bark, causing some injuries to underlying cambium. Bark is loosened from these activities and may allow development of cankers. Older stone fruits (Prunus spp.) with preexisting wounds are most commonly attacked. Several leafrollers in the genus Platynota1 are minor pests of fruit crops in most areas of the U.S. In the eastern states, variegated leafroller (P. flavedana) is occasionally damaging to strawberry and apples when larvae incidentally chew young fruit that is incorporated along with the leaves they silk together. The host range is fairly wide and also includes rose, peach, azalea, begonia, and helianthus, although leaf­feeding injuries are minor. Variegated leafroller has two generations in the Midwest, with peak egg­laying in June and again in late August in Michigan. Winter is spent as a partially grown larva at the base of plants, and some spring feeding on low­growing plants occurs in spring before pupation. Tufted apple bud moth (P. idaeusalis) has become an increasingly important pest of apples in the upper Midwest and eastern states. It produces a unique leaf injury as larvae partially sever the petiole, causing the leaf to hang and wilt. The last­stage larva folds and ties the leaf and feeds in it. One generation is produced per year, with most eggs being laid in mid­ to late June. Blackhaw, blackberry, Osage orange, and goldenrod are other hosts.

132

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B

C D E

G H

F

A. Larvae and damage produced by light brown apple moth. TODD M. GILLIGAN AND MARC E. EPSTEIN, USDA ITP, BUGWOOD.ORG

B. Orange tortrix larva. ERIC LAGASA, WASHINGTON STATE DEPARTMENT OF AGRICULTURE, BUGWOOD.ORG

C. Orange tortrix adult. ERIC LAGASA, WASHINGTON STATE DEPARTMENT OF AGRICULTURE, BUGWOOD.ORG

D. Larva of the pine tube moth. DAVID SHETLAR

E. Symptoms produced by

a larva of the pine tube moth. DAVID SHETLAR

F. Larva of the holly bud

moth/blackheaded fireworm. ROBIN ROSETTA, OREGON STATE UNIVERSITY

G. Damage produced by

blackheaded fireworm/holly bud moth. ROBIN ROSETTA, OREGON STATE UNIVERSITY

H. Tufted apple bud moth. DAVID SHETLAR

Insects that chew on Leaves and needLes

LeaFRoLLeRs, LeaFFoLdeRs, and LeaFtIeRs Omnivorous leafroller (Platynota stultana)1 occurs throughout much of the southern half of the U.S. It has an extremely wide host range that includes most tree fruits, cotton, rose, chrysanthemum, and numerous weed hosts including lambsquarter, curly dock, little mallow, and many legumes. It typically ties together and feeds on new foliage; however, most damage occurs when these feeding shelters also include fruit that is subsequently scarred by shallow feeding grooves. Several generations may occur, with up to six per year reported from Arizona. A species of similar habits is Sparganothis sulfureana,1 variously known as sparganothis leafroller, blueberry leafroller, or cranberry leafroller. It also has a wide range of hosts, as diverse as apple, clover, buttercup, strawberry, blueberry, cranberry, willow, and pine. Two generations are produced. Overwintering larvae mature during spring, and the adults appear in June. Eggs are laid in masses, and the larvae feed on foliage, flowers, and fruit. Fruits may be tunneled but are also chewed on the surface, a type of injury different from that produced by cranberry fruitworm (page 552). The second­generation adults are present in late August and September. Apple pandemis (Pandemis pyrusana)1 is a moderately important pest of apple, pear, cherry, and caneberries in the Pacific Coast States and British Columbia. Larvae are green with a straw­ or gold­colored head and very similar to obliquebanded leafroller and orange tortrix in the damage they produce. Although primarily a leaf feeder, apple pandemis may incidentally chew blossoms and the surface of young fruit during the spring generation. The summer generation limits feeding to leaves, producing windowpaning symptoms. A related species is threelined leafroller (P. limitata), which feeds on willow, aspen, ash, oak, apple, birch, and many hardwoods in much of the northern U.S. and Canada. Pandemis cerasana is known to feed on oak and raspberry in British Columbia. Several species of Ancylis1 tie leaves and occasionally damage fruit of many species. Sycamore leaffolder (A. platanana) is a common species in the eastern states. It folds the leaves of sycamore and develops in a silken tube at the base of the fold. Strawberry leafroller (A. comptana fragariae) is widespread in the U.S. and occasionally damaging to strawberry, less commonly raspberry. Adults emerge in April and May and lay eggs singly on foliage. The larvae tie together the leaflets and skeletonize them from within. Two to three generations per year are reported to occur in Illinois. Ancylis discigerana and A. logiana are two eastern species commonly associated with leaffolding of birch.

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A

B

D

E F

A. Omnivorous leafroller. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

B. Apple pandemis larva. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Omnivorous leafroller adult. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

D. Omnivorous leafroller egg mass. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

G

E. Injury and larva produced

by sycamore leaffolder.

JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

F. Strawberry leafroller. STEVEN ASMUS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

G. Leaf injury produced by birch

leaffolder, Ancylis discigerana.

RONALD S. KELLY, VERMONT DEPARTMENT OF FORESTS, PARKS AND RECREATION, BUGWOOD.ORG

Insects that chew on Leaves and needLes

LeaFRoLLeRs, LeaFFoLdeRs, and LeaFtIeRs The leaf­tying habit of hydrangea leaftier (Olethreutes ferriferana)1 produces a conspicuous cupping of leaves on the top of hydrangea plants. Eggs are laid on the tips of plants in spring and the larvae then fold over three or four leaves, incorporating the developing flower buds within this shelter. It is presently found east of the Mississippi. In the Pacific States the ominivorous leaftier (Cnephasia longana)1 is also found throughout much of the U.S. It feeds on a wide range of plants, including vetch, wild daisies, flax, strawberry, filbert, pear, hops, and many nursery crops. Winter is spent as a minute first­stage larva that becomes active during warm days in late winter and early spring. It then disperses, being wind­blown on silk threads, and crawls to suitable plants. The larvae first tunnel into the plant, creating small mines in leaves. Later stages feed on foliage, usually at the tips of plants they tie loosely with silk. In the northeastern states, sumac leafroller (Episimus argutanus)1 can be common on sumac, witch­hazel, and poison ivy. Two generations are produced annually. In the Pacific Northwest, carnation tortrix (Cacoecimorpha pronubana) may be common on cherry laurel; it is also known to feed on avocado, olive, and carnation. Redbud leaves are folded and tied with silk by redbud leaffolder (Fascista cercerisella).2 The larvae, which are marked with black and white bands, are highly active when disturbed. Two generations are produced annually. Leaffolding of grapes and Virginia creeper can be produced by grape leaffolder (Desmia funeralis).3 Younger larvae initially feed in small protected sites on the vines. Later they form shelters of folded or rolled leaves within which they feed, producing a conspicuous skeletonizing type of injury. The insect is widespread in the North America and will normally produce three generations in southern areas, two in the northern areas of its range. Winter is spent in the pupal stage under fallen leaves and other debris around the base of plants. New growth of canna may be fed on by lesser canna leafroller (Geshna cannalis).4 Most feeding occurs on the surface of unfolded leaves, which may be loosely tied together. In Florida, adult moths may begin to lay eggs in late winter, and several generations can be completed at intervals of about 1½ months. Lesser canna leafroller is restricted to the southeastern U.S., where it commonly occurs in co­infestation with larger canna leafroller (page 138). Genista caterpillar (Uresiphita reversalis)4 feeds on crape myrtle, Texas laurel, honeysuckle, golden­ chain, and yew in many areas in the southern half of the U.S. The caterpillars are about 1 inch when full grown, orange or green with small patches of white hairs emerging from dark spots. Eggs are laid as small masses, and early­stage larvae feed in groups, producing some associated webbing. Later­stage larvae disperse throughout the plant, and after feeding is completed they frequently wander from the plant and may pupate on adjacent buildings. Two generations are produced annually. American lotus borer (Ostrinia penitalis)4 is a common insect associated with American lotus in eastern North America. Adults are first active in midspring, and eggs are laid as amber­colored masses on the leaf surface. The young caterpillars concentrate feeding at the edge of the leaf. Skeletonizing injuries are typical, and large amounts of webbing are produced to prevent larvae from being washed off plants and to afford protection. Late­stage caterpillars migrate to petioles where they excavate a tunnel. After feeding for a while in this protective retreat, they pupate. A midsummer generation is subsequently produced. American lotus borer is capable of swimming, and there can be considerable movement among plants and migration to shoreline plants. Pupation is also reported to commonly occur in stems of various smartweeds and knotweeds and occasionally in other plants.  Lepidoptera: Tortricidae; 2 Lepidoptera: Gelichiidae; 3 Lepidoptera: Crambidae; 4 Lepidoptera: Pyralidae

1

136

A C

B A. Hydrangea leaftier

injury and larva. DAVID SHETLAR

B. Adult of the

hydrangea leaftier. DAVID SHETLAR

C. Carnation tortrix

larva.

ERIC LAGASA, WASHINGTON STATE DEPARTMENT OF AGRICULTURE

D. Genista caterpillars.

E

DAVID SHETLAR

E. Leaffolding symptom

produced by redbud leaffolder. DAVID SHETLAR

F. Larvae of the redbud

leaffolder.

DAVID SHETLAR

G. Grape leaffolder. DAVID SHETLAR

F

G

D

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SKIPPERS Skippers are a family (Hesperiidae) within the order Lepidoptera that have adults that fly during the day. Most closely related to the other day-flying Lepidoptera, the butterflies (Papilionidae, Pieridae, Nymphalidae, Lycaenidae), adult skippers can be differentiated by having a relatively stout body, with wings proportionately smaller than butterflies, and antennae that terminate in a hook (rather than a club). Larvae of skippers are marked by having a large round head, and pupal stages are usually covered with a loose cocoon of silk. Approximately 275 species occur in North America, the great majority of which develop feeding on grasses. Silverspotted Skipper (Epargyreus clarus)1 is the most commonly encountered skipper, found throughout most of the southern border provinces of Canada and most of the continental U.S. except the Great Basin and west Texas. Adults are light brown, heavy-bodied butterflies with a wingspan ranging from 1¾ to 2⅝ inches. The overall color of the wings is brown with a yellow-brown band, but the underside of the lobed hindwing has a metallic silver band. Larvae develop on wisteria and various leguminous plants such as black locust, honeylocust, false indigo bush, soybean, (Amorpha) and Cassia species. A full-grown larva is about 2 inches long. It has a dark reddish brown head with large yellow eye patches. The prothoracic shield is brown and the abdomen is yellow with darker transverse stripes and spots. During egg laying, females alight on potential host plants to attach single eggs to leaves. The eggs are green with a red top. After hatching, the young larvae make shelters on the apical halves of leaves by cutting a flap on the leaf margin, folding it over and attaching it with silk. Larger larvae often silk several leaves together to form shelters. They leave the shelters only to feed or to make larger shelters. When mature, the larvae pupate inside the leaf nest. The pupal stage gives rise to summer adults, but pupae formed in the fall spend the winter in the leaf nests. In the more northern parts of its range, one generation is normal, but three to four generations can occur in southern states. Larger canna leafroller (Calpodes ethlius)1 chews the leaves of canna lily in the southern and parts of the eastern U.S. It also characteristically folds leaves, fastening them with silk. Several generations can be completed, with larval development taking about 2 weeks. Pupation occurs on a pad of silk in the folded leaf. Peak injury is usually observed in mid- to late summer.

A. Silverspotted skipper adult.

E. Larva of the larger canna leafroller.

DAVID CAPPAERT, BUGWOOD.ORG

DAVID SHETLAR

B. Leaf folding produced by silverspotted skipper larva.

F. Pupa of the larger canna leafroller.

DAVID SHETLAR

HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

C. Larva of the silverspotted skipper.

G. Adult of the larger canna leafroller.

DAVID SHETLAR

HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

D. Leafrolling produced by larger canna leafroller. DAVID SHETLAR

138

A C D

E

F

G

139

B

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SKIPPERS Larvae of fiery skipper (Hylephila phyleus)1 chew blades of various turfgrasses. Bermudagrass is often preferred, but St. Augustinegrass, bentgrass, and some grassy weeds such as crabgrass are also eaten. The insect is very widely distributed across the southern half of the U.S., and there are reports of it occasionally being injurious in California and Hawaii. Larvae have a black head with a distinct constriction just behind it. The body color is pale greenish yellow, but larvae darken with age. They construct a loosely webbed shelter among the base of grass plants from which they emerge to forage on nearby grass blades at night. Adults are orange, yellow, or brown heavybodied butterflies with a wingspan of about 1 inch. A great many other skippers develop on grasses. A few of these will feed on turfgrasses, including Peck’s skipper (Polites peckius) and the European skipper (Thymelicus lineola).1 These grass-feeding skippers can be common insects, with adults often seen visiting garden flowers, but they do not occur in populations large enough to cause significant turf injury. Bean leafroller (Urbanus proteus)1 is a tropical species restricted to the extreme southeastern U.S. Adults are sometimes known as “longtail skippers” because they possess tail-like extensions of the wings. Females lay eggs singly or in small groups. The caterpillars cut a small patch at the leaf edge and fold and fashion it into a shelter. They emerge to feed at night on leaves and may cause extensive defoliation to beans late in the summer. As larvae get older, they construct a series of shelters, in the last stage webbing together two separate leaves. Pupation occurs in these folded leaves. A generation can be completed in about a month, and several generations are produced during the year. Bean leafroller is sensitive to cold temperatures and probably dies back in most years to southern Florida, dispersing northward the following year.  Lepidoptera: Hesperiidae

1

140

A B

A. Adult of the fiery skipper. DAVID SHETLAR

B. Fiery skipper larva. DAVID SHETLAR

C. Peck’s skipper. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Larva of Peck’s skipper in lawn. DAVID SHETLAR

E. Larva of the bean leafroller. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

F. Adult bean leafroller. JOHN CAPINERA, UNIVERSITY OF FLORIDA

C D

E

F

INSECTS THAT CHEW ON LEAVES AND NEEDLES

CATERPILLARS THAT PRODUCE LARGE SILKEN SHELTERS AND TENTS Caterpillars of several families of Lepidoptera and sawfly larvae of one Hymenoptera family collectively produce a large silken structure within which they rest and/or feed. Perhaps best known are the tent caterpillars (Lasiocampidae), a few of which may be locally common on trees and shrubs in midspring. Many other caterpillars that produce large silken webs may be known as “webworms,” a term that is more loosely applied and includes several caterpillars that are normally solitary (pages 122 and 128).

Mimosa Webworm (Homadaula anisocentra)

1

Eggs of mimosa webworm scattered among webbing. DAVID SHETLAR

hosts Honeylocust, mimosa. Damage Larvae feed on leaf surfaces of honeylocust and mimosa, producing skeletonizing injuries that cause leaves to turn dull gray or appear scorched brown. Individual larvae web together several leaflets and may feed together in groups, creating large areas of unsightly webs. Isolated trees, particularly adjacent to buildings, tend to be most consistently damaged. Distribution Mid-Atlantic and southeastern states west to eastern Kansas and Nebraska. Appearance Caterpillars are grayish to dark brown, sometimes tinged with rose or pink. Full grown they are about ⅝ inch and extremely active, wriggling and dropping on a silken strand when disturbed. Adults are undistinguished gray moths, rarely seen, with a wingspan of ½ inch; wings have a silver sheen and dark blue spots. Life History and Habits Adults begin to lay rosy-colored eggs in late May into June on flowers and foliage. The young larvae produce silk and skeletonize adjacent foliage and flowers. As they get older, their webbing bcomes more extensive and may coalesce with that of adjacent larvae. By midsummer the larvae descend to the ground on silken threads and pupate in cocoons in bark cracks, on adjacent buildings, and among ground cover. A second generation with peak feeding injury in August is often more conspicuously damaging. A third generation is reported in the southeastern area of the range. The overwintering stage is a pupa.

Other Webworms Juniper webworm (Dichomeris marginella)2 develops on most Juniperus species and occasionally on arborvitae. It is a European species that apparently has been introduced on multiple occasions and can be found in many areas of the U.S. and southern Canada. Young larvae mine needles. Later-stage larvae often feed in small groups, producing a shelter of webbing that ties needles together and incorporates bits of chewed needles and frass into the “nest.” Winter is spent in the shelter in the form of late-stage larvae that pupate in spring. One generation is produced per year. 142

A. Webbing of honeylocust leaves produced by mimosa webworm. DAVID SHETLAR

B. Adult of the mimosa webworm. DAVID SHETLAR

C. Mimosa webworm. DAVID SHETLAR

D. Pupae of mimosa

webworm within bark cracks of a honeylocust tree.

A B

DAVID SHETLAR

E. Larva of the juniper

webworm.

CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

f. Juniper webworm adult. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

g. Webbing mixed with

frass and needle fragments produced by juniper webworm.

C D

E

g

f

CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

INSECTS THAT CHEW ON LEAVES AND NEEDLES

CATERPILLARS THAT PRODUCE LARGE SILKEN SHELTERS AND TENTS Cotoneaster webworm (Athrips rancidella)2 is also a European species currently established in northern California and the Pacific Northwest. During spring the larvae skeletonize leaves and make dense webs on cotoneaster that are filled with leaf fragments and frass. Adults are typically present in June and July, when females lay eggs in small groups on leaves. After egg hatch the young larvae feed for about a month then move to branches where they construct a silken shelter, usually in the axils of branches. They remain dormant through winter, resuming activity in March. There is one generation per year. Rock cotoneaster (Cotoneaster horizontalis) is most commonly damaged. Uglynest caterpillar (Archips cerasivorana)3 is found across the northern U.S. and southern Canada. It feeds on a wide range of trees and shrubs, although cherry and chokecherry are most commonly infested. Uglynest caterpillars feed in groups, creating large, loose silken shelters that cover foliage in a manner similar to that of fall webworms. One generation is produced per year, with the olive green caterpillars present from the time of egg hatch in late spring through much of the summer. A large cluster of leaves in the terminals of black and red Cotoneaster webworm. KEN GRAY COLLECTION, oaks may be similarly tied in by oak webworm (A. fervida), a species that OREGON STATE UNIVERSITY occurs from the upper Midwest and eastern Canada into North Carolina. Ailanthus webworm (Atteva punctella)4 is one of the few insects commonly associated with tree-ofheaven. It feeds on leaves and loosely covers them with silk. Pine webworm (Pococerca robustella)5 feeds on several species of pines throughout the eastern U.S. and Canada. In northern areas young caterpillars are present in late spring and originally feed as needleminers. As they get older, they feed in groups, loosely webbing together needles of pine terminals. One generation is produced annually in northern states, with winter spent as a pupa in a cocoon in soil. In the southeast two generations may be produced. Barberry webworm (Omphalocerca cariosa)5 is an eastern species associated with barberry (Berberis spp.) and pawpaw. The larvae are black, about 1½ inches long when full grown, and feed on leaves and new shoots in a loose silken shelter. It occurs across the southeastern U.S., from Texas to Florida and as far north as Illinois. Mahogany webworm (Macalla thrysisalis)5 feed on the spring flush of growth of West Indies mahogany (Swietenia mahagoni) in southern Florida and other areas where this plant grows. Adults lay eggs shortly after the spring flush of growth is produced and the larvae subsequently tie together a small number of leaves on which they feed. The larvae are brightly colored, predominantly yellow with alternating black and white stripes. Feeding occurs on the new growth and is usually concluded within a couple of weeks. One generation is produced per year.  Lepidoptera: Glyphipterygidae; 2 Lepidoptera: Gelechiidae; 3 Lepidoptera: Tortricidae;

1

 Lepidoptera: Yponomeutidae; 5 Lepidoptera: Pyralidae

4

144

A

B

C D E

F

G

A. Webbing of terminal growth produced by uglynest caterpillar. WHITNEY CRANSHAW

B. Uglynest caterpillar. WHITNEY CRANSHAW

C. Webbing and larvae of the oak webworm. STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

H

D. Adult of the ailanthus webworm. DAVID SHETLAR

E. Ailanthus webworm. DAVID SHETLAR

F. Webbing and frass associated

with pine webworm.

CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

G. Pine webworm larva. CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

H. Barberry webworm within a sheath of silk. J. A. DAVIDSON, UNIVERSITY OF MARYLAND, BUGWOOD.ORG

INSECTS THAT CHEW ON LEAVES AND NEEDLES

CATERPILLARS THAT PRODUCE LARGE SILKEN SHELTERS AND TENTS

Fall Webworm (Hyphantria cunea)1 hosts Fall webworm has one of the widest host ranges of any caterpillar and may feed on more than 100 species of deciduous trees and shrubs. Some plants tend to be preferred, including cottonwood, chokecherry, mountainash, pecan, elm, willow, and various fruit and nut trees. Damage The larvae feed on leaves and build unsightly silken tents. Heavy infestations can defoliate trees. Wandering larvae are sometimes a serious nuisance. Fall webworm is the most common tent-making caterpillar in much of North America. Distribution Widely distributed through most of North America, extending from southern Canada to northern Mexico. Appearance Larvae of fall webworm are hairy caterpillars with distinct paired dark spots on each segment of the back. They can be variable in color, however, with both black- and red-headed races present, sometimes together. The general color of the caterpillars is also variable, with the black-headed form tending to be yellow or pale green with light-colored hairs. The red-headed form is usually darker with reddish brown hairs. Caterpillars are about 1 inch long when mature. The adults are attractive satiny white moths, sometimes with brown or black spots. The wingspan is about 1½ inches. Life History and Habits Fall webworm spends the winter as a pupa in a flimsy light-colored cocoon found in protected areas such as bark furrows, crevices along the sides of buildings, or mixed among debris around the soil surface. In southern areas of its distribution, adults begin to emerge in early spring, whereas emergence usually occurs in late June or July in northern areas. Eggs are laid in masses on the underside of leaves, and the young larvae feed together, first skeletonizing the leaf and then incorporating leaves and ultimately entire branches in their loosely spun tent of silk. Unlike in tent caterpillars (below), all larval development and feeding occur in the tents, into which leaf fragments, droppings, and cast skins become incorporated. The caterpillars, when disturbed, often twitch in an effort to deter potential predators. When full grown the larvae usually wander from the plant and search for a protected location to pupate. A single generation occurs in northern areas of the range; in southern states, there may be up to four generations per year.  Lepidoptera: Erebidae (Arctiinae)

1

146

A

B C D

E

F

A. Tent produced by fall webworm. WHITNEY CRANSHAW

B. Late-instar larvae of fall webworm,

brown morph.

WHITNEY CRANSHAW

C. Early-instar tent produced by

fall webworm, black headed morph. DAVID SHETLAR

D. Mating pair of fall webworm moths. DAVID SHETLAR

E. Fall webworm egg mass. DAVID SHETLAR

F. Fall webworm larvae at egg hatch. DAVID SHETLAR

INSECTS THAT CHEW ON LEAVES AND NEEDLES

CATERPILLARS THAT PRODUCE LARGE SILKEN SHELTERS AND TENTS

Eastern Tent Caterpillar (Malacosoma americana)1 hosts Rosaceous plants including most fruit trees (apple, crabapple, plum, cherry, hawthorn); sometimes found on poplar, willow, ash, and birch. Damage Caterpillars chew leaves early in the season and can cause significant defoliation. Developing fruit may be chewed incidentally. Conspicuous tents of tightly woven silk in branch crotches attract attention and may be considered unsightly. Distribution Throughout the eastern U.S. and southern Canada, to the Rocky Mountains. Appearance Larvae are overall dark, primarily black, with a distinct light stripe on the back and a series of blue markings on the sides. Adults are rather stout moths with reddish brown wings marked with a pair of wavy light bands. Life History and Habits Eggs are laid on twigs as distinct masses, shiny black and covered with varnish-like material (spumaline). They hatch shortly after bud break, and the young larvae immediately begin to spin a silken mat in a branch crotch near the egg mass. The tent is gradually expanded as the caterpillars get older. Most often the caterpillars feed at night on nearby foliage, returning to rest together on or in the tent during the day. Late-stage caterpillars tend to disperse through the plant and feed in a more solitary manner. When full grown they migrate from plants and produce white or creamy white cocoons on nearby trunks or rocks, under eaves, or in other sheltered locations. Adults emerge in early summer; after mating, females attach the overwintering egg masses to branches of host trees. One generation is produced per year.

Other Tent Caterpillars Western tent caterpillar (Malacosoma californica) is found in much of the U.S. from the Great Plains westward. It is rarely a pest of ornamental plantings but is common on wild hosts such as mountain-mahogany, wax currant, and aspen. Plum, other fruit trees, willow, and several other deciduous woody plants are less common hosts. The caterpillars can be distinguished from other species by being slightly hairy and having a typically light brown general coloration with powdery blue markings along the sides and a blue head; however, several races are recognized with slightly different appearances.

above: Western tent caterpillars. WHITNEY CRANSHAW

right: Early stage colony of western tent caterpillar, shortly after egg hatch. WHITNEY CRANSHAW

B C

A D

E

F

G

A. Colony of eastern tent caterpillar. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Eastern tent caterpillar. DAVID SHETLAR

C. Early stage colony of eastern

tent caterpillar. DAVID SHETLAR

D. Egg mass of eastern tent

caterpillar at egg hatch. DAVID SHETLAR

E. Egg mass of western tent caterpillar. WHITNEY CRANSHAW

F. Cocoon of the western tent caterpillar. WHITNEY CRANSHAW

G. Mating pair of western

tent caterpillar moths. WHITNEY CRANSHAW

INSECTS THAT CHEW ON LEAVES AND NEEDLES

CATERPILLARS THAT PRODUCE LARGE SILKEN SHELTERS AND TENTS Southwestern tent caterpillar (M. incurva) can be an important pest west of the Rockies, most commonly feeding on poplar and cottonwood along riverways. Eggs hatch very early, in late March or early April, and feeding is completed by mid-May. In the southwestern U.S., Sonoran tent caterpillar (M. tigris) feeds on native stands of oak, especially Gambel oak. In the Pacific States oak is the host for Pacific tent caterpillar (M. constricta). Forest tent caterpillar (M. disstria) is the most widespread and perhaps most frequently damaging tent caterpillar in North America. Ash, aspen, various fruit trees, oak, poplar, and willow are among the many deciduous trees this insect feeds on. In many areas it has short-lived outbreaks during which there is extensive defoliation, particularly to aspen or oak. At these times large numbers of wandering caterpillars may be present, leading to them being locally called “armyworms.” Although this is often the most common of the tent caterpillars (Malacosoma spp.), it does not make a permanent silken tent in branch crotches. Instead, colonies make several resting mats of lightly spun silk during a season on trunks and larger branches. The forest tent caterpillar is also distinctive in having an electric blue color and a series of light “keyhole” patterns along its back.  Lepidoptera: Lasiocampidae

1

Other Tent-making Caterpillars Poplar tentmaker (Clostera inclusa)1 occurs over a wide area of southern Canada and the eastern half of the U.S., ranging south to Georgia. It develops on aspen, poplar, and willow. Larvae feed gregariously and construct a structure of leaves loosely tied with silk. Two generations are produced, with eggs from the overwintered generation laid in March and April, followed by a summer generation with eggs laid mostly in July and August. Winter is spent in a cocoon around the base of previously infested trees. silverspotted tiger moth (Lophocampa argentata)2 is a tent-producing species present in forested areas of the Pacific Northwest North America, where it feeds primarily on Douglas-fir. Eggs are laid in clusters on twigs and needles during midsummer. In about 3 weeks the larvae emerge and begin to produce loose webbing. They feed together and continue to expand the silken tent. They remain in the tent through the winter and resume feeding with the return of warm weather. Late-stage larvae then disperse and feed as individuals. Pupation occurs in late spring in a brown cocoon attached to plants or among debris on the ground. There is one generation per year. In the Rocky Mountain region a related species, L. ingens, feeds on pinyon and juniper in a similar manner. Lophocampa sobrina occurs on Monterey pine in California. 1

Poplar tentmaker.

Lepidoptera: Notodontidae; 2 Lepidoptera: Erebidae (Arctiinae)

STANTON GILL, UNIVERSITY OF MARYLAND COOPERATIVE EXTENSION, BUGWOOD.ORG

150

A

B E D

C

F

G

H

A. Pacific tent caterpillar. DONALD OWEN, CALIFORNIA DEPARTMENT OF FORESTRY AND FIRE PROTECTION, BUGWOOD.ORG

B. Eastern tent

caterpillar (left) and forest tent caterpillar (right). DAVID SHETLAR

C. Southwestern tent

caterpillar.

DAVID LEATHERMAN

D. Forest tent caterpillars. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

E. Mass of forest tent

caterpillars resting on silk mat. DAVID SHETLAR

F. Forest tent caterpillar,

adult female. DAVID SHETLAR

G. Tent produced by

Lophocampa ingens. DAVID LEATHERMAN

H. Forest tent caterpillar,

adult male.

DAVID SHETLAR

I. Late-instar larva of

Lophocampa ingens. FRANK PEAIRS

I

INSECTS THAT CHEW ON LEAVES AND NEEDLES

WEBSPINNING SAWFLIES The webspinning sawflies (Pamphiliidae) are the only web-producing larvae in the order Hymenoptera one may find associated with plants. Unlike other sawflies, the larval stages in members of this family have very reduced legs and prolegs and move little about the plants on which they feed. Instead, most construct shelters of webbing, of a form similar to those produced by certain webworms and tent-making caterpillars, and spend much of the time resting on or within the silken shelter. Although webspinnng sawflies occasionally attract some attention and interest because of the tents they construct, they are not common insects and none are considered serious plant pests. Pine false webworm (Acantholyda erythrocephala)1 is found in much of the northern U.S. and southern Canada. Adults insert small groups of eggs into needles in spring, and the newly hatched larvae spin webs at the base of needles. They feed in this shelter, cutting adjacent needles, which they pull into the web. Often several feed in a loose group, creating a messy “nest” of silk incorporated with needle fragments and frass. When full grown they drop to the ground and spend winter as full-grown larvae in cocoons in the soil at the base of previously infested plants. Eastern white pine and red pine are favored hosts. Other species of Acantholyda also feed on pine. Cephalcia species1 also feed on pines as well as spruce. Some feed gregariously, producing messy nests. Most have solitary habits and live inconspicuously in a silken tube at the base of needles. Some sixteen species of webspinning sawflies in the genus Pamphilius1 occur in North America. Most are solitary leafrollers of various deciduous trees and shrubs, curling leaves and fastening them with silk. P. phyllisae feeds on northern red oak and curls a new leaf after each molt. Its life cycle may take more than a year to complete under certain conditions. Larvae normally are present on plants for about 3 weeks, after which they move to the soil and produce overwintering cocoons. Other species include peach sawfly (P. persicus) and blackberry sawfly (P. dentatus). Plum webspinning sawfly (Neurotoma inconspicua)1 is found in plum and sand cherry throughout much of the midwestern and northeastern U.S. and southern Canada. It feeds in groups, creating nests of large, loose webbing that enclose the tips of branches in a manner similar to that of uglynest caterpillar. Larvae are grayish yellow. One generation is produced annually. In the southern U.S., cherry webspinning sawfly (N.  asciata) has similar habits and is associated with black cherry.  Hymenoptera: Pamphiliidae

1

Adult of Oncyolyda sitkensis, a webspinning sawfly that feeds on blackberry.

Leaf tying and frass associated with a webspinning sawfly on blackberry. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Young larva of Oncyolyda sitkensis, a webspinning sawfly that feeds on blackberry. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

152

A C D

A. “Nest” of silk and frass produced by pine false webworm. DAVID SHETLAR

B. Pine false webworm larva. DAVID SHETLAR

C. Male of the pine

false webworm. DAVID SHETLAR

D. Female of the pine

false webworm. DAVID SHETLAR

E. Mixture of frass and silk

produced by a webspinning sawfly on pine. DAVID LEATHERMAN

F. Webspinning sawflies

on cherry.

DAVID SHETLAR

F

B E

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SAWFLIES In the diverse order Hymenoptera (ants, bees, wasps) few species feed diretly on leaves of plants, and many are critically important in pollination or as natural enemies of plant-feeding insects. Among those that do chew on leaves, the sawflies are by far the most commonly encountered. Larval stages of these insects often have an appearance very similar to that of many caterpillars (larvae of Lepidoptera) and similarly possess prolegs on the abdomen. They can be distinguished from caterpillars by having 6–8 pairs of prolegs (versus 2–5), none of which are tipped by the hooks (crochets) found on caterpillars. Most sawfly larvae are hairless, but some species may be covered with short spines. Adult sawflies are heavy-bodied, nonstinging wasps, uncommonly noticed, that insert eggs into foliage with a sawlike ovipositor. The two main families of sawflies are the conifer sawflies (Diprionidae) and the common sawflies (Tenthredinidae). About three dozen species of conifer sawflies occur in North America, all of which feed on needles of conifers. Larvae of the conifer sawflies often feed in groups and often have bizarre defensive behaviors such as mass twitching, arching, and disgorging of sticky fluids when disturbed. The common sawflies (Tenthredinidae), constitute a much larger insect family (more than 700 North American species) and occur on a wide range of broadleaf plants.

European Pine Sawfly (Neodiprion sertifer)1 hosts Pines, particularly mugho and tabletop pines. Damage Larvae consume the older foliage in spring, before bud break. Seriously affected plants have a tufted “bottle brush” appearance with only new needles present. Distribution Generally distributed throughout the Midwest, Northeast, and parts of southern Canada. Appearance Larvae are grayish green and about 1 inch when full grown. A light stripe runs down the back, and a light stripe followed by a dark green stripe runs along the sides. Adults are about ⅓ inch long. Males are nearly black and have highly feathered antennae. Females are reddish brown and somewhat larger. Life History and Habits European pine sawfly spends winter in the egg stage, inserted in needles. Eggs hatch in midspring and the larvae feed on needles, often in small groups, with three or four per needle being common. When disturbed, they raise both their head and tail in defense. In late spring or early summer, fullgrown larvae move to soil or bark cracks where they form a cocoon and pupate. Adults emerge in late August and September. Females insert six to eight of the overwintering eggs per needle and may lay eggs in about a dozen individual needles. Egg-laying scars may be quite visible, particularly after frosts cause the wounded areas to yellow.

Other Conifer Sawflies Almost three dozen Neodiprion species develop on conifers in North America, mostly on pines. Redheaded pine sawfly (N. lecontei) is an important species in parts of the midwestern U.S. and southeastern Canada. It feeds on two- and three-needle pines, including Scotch, jack, shortleaf, loblolly, slash, red, and mugho. It produces two generations over much of its range, with the spring generation stripping old needles before bud break and the summer generation consuming new needles. Defoliated pines can be killed or have dead branches. Redheaded pine sawfly is gregarious and may form feeding groups that include dozens of larvae that twitch in unison when disturbed. Winter is spent as a prepupa in the cocoon, which is formed among leaf litter or dug shallowly in soil. Redheaded pine sawfly may remain dormant for a few years in this stage. Adults lay eggs in slits in rows along the needle edge. 154

A

B C

D E

F

A. European pine sawfly larvae. DAVID SHETLAR

B. Damage produced by European pine sawfly. DAVID SHETLAR

C. European pine

sawfly, adult female. DAVID SHETLAR

G

D. European pine

sawfly, adult male. DAVID SHETLAR

E. Eggs of European

pine sawfly, inserted into needles. DAVID SHETLAR

F. European pine

sawfly larvae shortly after egg hatch. DAVID SHETLAR

G. Redheaded pine

sawflies.

DAVID SHETLAR

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SAWFLIES Among the other Neodiprion species of importance, almost all occur in forest sites: — — —

— — —

N. swainei, Swaine jack pine sawfly, a common species in eastern Canada that develops primarily on Jack pine; N. autumnalis, a common “pine sawfly” of western forests, particularly damaging to ponderosa pine. Feeding damage occurs in mid- to late summer; N. pinetum, white pine sawfly, a species that occurs throughout the natural range of its primary host, eastern white pine. Both new and old needles are consumed by this species, which can be seriously damaging during outbreaks; N. excitans, blackheaded pine sawfly, common on loblolly and shortleaf pines in the southeastern and Gulf states. Three to four generations per year may occur in southern areas of its range; N. edulicolis, pinyon sawfly, a common and sometimes outbreak species of pinyon in the southwestern states; Damage caused by pinyon sawflies. and N. tsugae, hemlock sawfly, found across the northern DAVID LEATHERMAN U.S. and Canada in association with the native range of either western or, possibly, eastern hemlock.

Introduced pine sawfly (Diprion similis)1 feeds primarily on white pine throughout the northeastern quadrant of the U.S. Scotch, jack, red, and Swiss mountain pines are less commonly infested. Adults lay about 10 eggs, in a row, on needles, and the young larvae feed gregariously in groups. The first-generation feeding occurs before bud break and confines feeding to the previous year’s needles, but a midsummer generation consumes both old and newly produced needles. Pupation occurs in a cocoon, often on the host tree. The most important sawfly affecting spruce is yellowheaded spruce sawfly (Pikonema alaskensis),1 a species restricted to western North America. Adults lay eggs in late spring on current-season needles or tender twigs, and the larvae consume the new growth. Larvae have a reddish yellow to chestnut brown head and an olive green body. A single generation is produced, with winter spent as a full-grown larva in a cocoon at the base of previously infested trees. The genus Monoctenus1 contains several species that are minor pests of conifers. Juniper sawfly (M. fulvus) feeds on the tips of junipers, sometimes checking the new growth and causing a thinning of the shrub; however, the larvae do not appear to feed heavily on shrubs, even when in high populations. Larvae are generally gray-green with an orange head. Arborvitae sawfly (M. melliceps) occasionally damages arborvitae and juniper in the northeastern states. Bull pine sawfly (Zadiprion townsendi)1 feeds on ponderosa pine needles in the western U.S. In an unusual life history, the larvae continue to feed on warm days throughout winter, becoming full grown in spring. Adults appear in summer to lay eggs, and the newly hatched larvae begin to feed on needles by early fall.  Hymenoptera: Diprionidae

1

156

A D

B

C

E

F

G

A. Swaine jack pine sawfly larvae. DAVID SHETLAR

B. Adult Neodiprion

autumnalis ovipositing into needles. DAVID LEATHERMAN

C. Cocoon of the

white pine sawfly. DAVID SHETLAR

D. White pine sawfly

H

I

larva.

DAVID SHETLAR

E. Imported pine sawfly. DAVID SHETLAR

F. Pinyon sawflies. DAVID LEATHERMAN

G. Mating pair of

imported pine sawfly. JOHN GHENT, BUGWOOD.ORG

H. Eggs of imported

J

K

pine sawfly inserted in needle. JOHN GHENT, BUGWOOD.ORG

I. Yellowheaded spruce sawfly. STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

J. Juniper sawfly. DAVID SHETLAR

K. Bull pine sawflies. WHITNEY CRANSHAW

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SAWFLIES

Imported Currantworm/Currant Sawfly (Nematus ribesii)1 hosts Currants, gooseberry. Damage The larvae chew the leaves of currants and gooseberries, often extensively defoliating plants early in the season. Foliage in the interior is damaged first, but all leaves may be eaten. Yield and quality of fruit can be affected by this injury. Distribution Northern half of U.S. and southern Canada. Appearance Larvae are generally light green-gray with numerous black spots; newly molted, they are uniformly light green. Adult females are thick-bodied wasps, about ⅓ inch long with a dark head and thorax and yellowish abdomen. Males are slightly smaller and more generally dark. Life History and Habits Imported currantworm spends the winter in a cocoon in the soil around previously infested currants and gooseberries. The adults usually emerge shortly after the first leaves have expanded, and females insert eggs along the main veins of the leaf underside. The larvae hatch about 7–10 days after eggs are laid and at first chew small shotholes in the leaf interior. Later they disperse throughout the plant and feed along the leaf margins, becoming full grown in about 3 weeks. Young larvae are pale green but develop distinctive dark spots as they grow and reach a size of about ¾ inch. The full-grown larvae drop to the ground and form a cocoon. Some pupate and emerge in late June and July, producing a small second generation. The majority remain dormant and emerge the following year.

Other Common Sawflies1 Willow sawfly (Nematus ventralis) is occasionally abundant on willow in the central states and Prairie Provinces. Larvae are dark green and commonly feed in groups. Multiple generations may be produced. Larvae may remain dormant for two winters before completing development and emerging as adults in spring. Two species of azalea sawflies (Amauronematus azalae, Nematus lipvskyi) are damaging to azaleas in much of the Midwest and Larvae of imported currantworm shortly after egg hatch, producing Northeast. The larvae are green and feed along the leaf edge, often holes in the leaf interior. consuming the entire leaf except the larger veins. One generation is WHITNEY CRANSHAW produced annually. Brownheaded ash sawfly (Tomostethus multicinctus) is a sporadic but important early-season defoliator of ash in Colorado and many eastern states. Green ash is particularly damaged, but all species are susceptible. Brownheaded ash sawfly spends the winter as a full-grown larva in a cocoon around the base of a previously infested ash tree. Pupation occurs in early spring. Adults are small black wasps that emerge in April and can sometimes be found in swarms around the tree. Females insert eggs into young leaves, usually around the edge, resulting in a slight distortion of the leaves. Early-stage larvae feed on the interior of the leaf, producing small pinhole feeding wounds. Older larvae feed extensively on the leaf, avoiding only the main veins. Larval development and feeding occur throughout May, and by early June individuals are full grown. Full-grown larvae shed a papery larval skin that remains attached to the leaf and then crawl to the ground, where they form protective cocoons. 158

A

B

C D

E F

A. Imported currantworm larvae. WHITNEY CRANSHAW

B. Adult female of the

imported currantworm/ currant sawfly. WHITNEY CRANSHAW

C. Eggs of imported

currantworm inserted into midribs of currant leaf. WHITNEY CRANSHAW

D. Adult of the willow sawfly. DAVID SHETLAR

G

E. Willow sawfly larvae. DAVID SHETLAR

F. Larva of the

azalea sawfly. DAVID SHETLAR

G. Larvae of the

brownheaded ash sawfly. JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Pinhole feeding wounds produced by young larvae of the brownheaded ash sawfly. JIM KALISCH, UNIVERSITY OF NEBRASKA

H

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SAWFLIES Blackheaded ash sawfly (Tethida cordigera) is associated with red, green, and white ash through much of the eastern U.S. It is also found in California. Habits are similar to those of brownheaded ash sawfly. Mountain-ash sawfly (Pristophora geniculata) is a common sawfly on mountain-ash east of the Mississippi River. Adults emerge in late spring and insert eggs in small groups along the leaf edge. The larvae usually feed gregariously, clinging to the leaf edge and consuming the entire leaf except the midrib before moving to the next leaf. Like many sawflies that feed as a group, they rear in unison in an S-shape when disturbed. Fullgrown larvae drop to the soil and form a cocoon. Some complete pupation and produce a second generation in late summer. Others remain as prepupae in the cocoon and winter in this stage. Columbine sawfly (Pristophora aquiligae) defoliates columbine in late spring in areas of the Midwest, the Rocky Mountain region, and some eastern states. Larvae are pale green and apparently only a single generation is produced. California pear sawfly (P. abbreviata) makes a semicircular cut, somewhat resembling that of leafcutter bees, in pear leaves. The larvae lie along the cut and blend well. There is only one generation produced, with peak feeding in late April and May. Chokecherry sawfly (P. serrula) is a common species on chokecherry in the Rocky Mountain States. Larch sawfly (P. erichsonii) is a European species that feeds on larch. It is now present in many areas of southern Canada and the northern U.S. Larvae of raspberry sawfly (Monophadnoides geniculatus) feed on the interior of raspberry leaves, cutting irregular holes between veins. When they are abundant, foliage may become very lacy, but raspberry sawflies develop rapidly and the full-grown larvae begin to crawl to the ground within about 2 weeks after hatching. They dig a small cell in the soil and spin a cocoon in which they remain until the following spring. Several sawflies develop on leaves of rose (also see roseslug, page 166). Larvae of the bristly rose sawfly (Cladius difformis) have a pale green body covered with short bristles. Curled rose sawfly (Allantus cinctus) is somewhat darker, with small white bristles. Both of these are European species now widely distributed in North America. More recently introduced are A. nigritibialis and A. viennensis, presently known to be present in parts of the Mid-Atlantic region and Ontario. In early stages, larvae of all of these sawflies skeletonize the leaves, but older larvae more generally chew foliage and can extensively defoliate plants. When full grown, larvae may move into the pith of stems to form a pupal chamber. Two generations are likely normal. Spiny oak sawfly (Periclista albicollis) develops on the leaves of several species of both red and white oaks. It ranges widely across the eastern half of North America in association with its hosts. Dusky birch sawfly (Croesus latitarsus) is a common defoliator of birch and found widely in North America. Gray birch is the favored host. Larvae strongly hold a rather unusual S-shaped form while they feed along the leaf margin. One or two generations may occur annually. Larvae of another sawfly associated with birch, the fringed birch sawfly (Dimorphopteryx melanognathus), are less commonly observed but have an unusual appearance with fringed projections along the sides of the body. Grape sawfly (Erythraspides vitis) feeds on wild grape in the southern U.S. The larvae are distinctly marked with a double row of black tubercles on each segment and feed as groups on the leaf underside. Violet sawfly (Ametastegia pallipes) feeds on wild and cultivated pansies and violets. The larvae are dark olive green with a black head. Several generations may occur, with injury most evident in late summer. Larvae skeletonize the underside of leaves, then feed more generally, later leaving the food host plant to pupate in the pith of larger nearby plants.

160

A

B

C A. Blackheaded ash

sawfly larva, recently molted DAVID SHETLAR

B. Mating pair of

blackheaded ash sawfly. DAVID SHETLAR

C. Mountain ash sawflies. DAVID SHETLAR

D. Columbine sawflies.

D

DAVID SHETLAR

E. Leaf injury produced

by raspberry sawfly. WHITNEY CRANSHAW

F. Bristly roseslug larva. DAVID SHETLAR

G. California pear sawfly

larva and damage. WHITNEY CRANSHAW

H. Dusky birch sawfly

E

larva.

DAVID SHETLAR

F G H

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SAWFLIES

Young larvae of poplar leaffolding sawfly (Phyllocolpa bozemani) induce an unusual leaf fold along the edge of poplar, cottonwood, and willow. The young larvae wound the expanding leaf, causing it to curl around them. Later they move out and feed along the leaf edge. There is normally only one generation per year, completed by early summer. Dogwood sawflies (Macremphytus tarsatus, M. testaceus) feed on leaves of various dogwood, particularly gray dogwood. They are most common in the northeastern U.S. and Great Lakes area but known as far west as Colorado. Larvae appear white due to a thick waxy coating in early stages and become prominently spotted in the last larval instar. When full grown the larvae move away from the plant and excavate a chamber within which they pupate, often boring into wood of nearby posts, retaining walls, or building siding. Monostegia abdominalis is also generally whitish, with some pale green coloration that is present in areas of eastern Canada and the northeastern U.S. It feeds on various Lysimachia (loosestrife, creeping jenny). Two generations are produced per year. Several grass sawflies in the genera Dolerus and Pachynematus develop on grasses, including some that may occur in turfgrass. Dolerus nitens is the most common turfgrass species in Ohio. Adults of both genera appear in very early spring, sometimes in numbers that alarm homeowners who see them on sidewalks and siding of their homes. The adults are primarily black, although some may have reddish markings. The larvae are present from April to early June. They are rarely noticed as they usually don’t feed during the day, although they may be active on overcast days. The body is solid color, ranging from shades of gray to green, with a light brown head. Occasionally they may be observed on sidewalks as they migrate in search of pupation sites; pupation occurs in the soil. Grass sawflies are more common on unmowed grasses, in pastures, and in small grains. The damage they produce is generally negligible, although Pachynematus setator (grass seed sawfly) can be a serious pest of grass seed production as they may chew through the stems. One of the sawflies of most unusual appearance is butternut woollyworm (Eriocampa juglandis). Larvae are covered with long threads of whitish wax and develop on the foliage of nut trees in the eastern states.  Hymenoptera: Tenthredinidae

1

Last-instar larvae of dogwood sawfly resting on underside of leaf. WHITNEY CRANSHAW

162

A. Leaf injury produced by poplar leaffolding sawfly.

A

WHITNEY CRANSHAW

B. Young larvae of

dogwood sawfly shortly after egg hatch. DAVID SHETLAR

C. Dogwood sawfly

larva.

WHITNEY CRANSHAW

D. Larva of Monostegia

abdominalis on Lysmachia. DAVID SHETLAR

E. Adult of the grass

sawfly.

DAVID SHETLAR

F. Grass sawfly. DAVID SHETLAR

G. Butternut

B

woollyworm.

C

BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

D

E

F

G

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SAWFLIES

Other Sawflies that Chew on Leaves Birch sawfly (Arge pectoralis)1 is the most commonly encountered of the argid sawflies, a small family of sawflies marked by dusky wings, a dark body, and unusually developed antennae on the males. They are found in the northeastern U.S. and southern Canada, where they feed primarily on birches, occasionally on alder and willow. Larvae feed during summer and are yellow with six dark spots along the side. Hollyhock sawfly (Neoptilia malvacearum)1 can be very damaging to hollyhock in Ohio and some MidAtlantic States. Young larvae first feed on the leaf undersurface and produce windowpane injuries on the leaves. They later skeletonize extensively. The larvae are light green with dark spots. Adults are all black or black with an orange thorax. Two generations normally occur in Ohio, with a small third generation in warm seasons. Hibiscus sawfly (Atomacerca decepta)1 has been reported to damage hibiscus, marshmallow, buttonbush, and some other perennial plants in the Mid-Atlantic States. Schizocerella lineata1 chews on the leaves of purslane. It is closely related to another purslane feeding species, S. pilicornis, which develops as a leafminer and does not feed externally as a defoliator. Elm sawfly (Cimbex americana)2 is a large sawfly, widely distributed with a host range that includes willow, elm, and occasionally basswood, birch, maple, poplar, and alder. When feeding, the larvae often coil the hind end around an adjacent twig. Elm sawfly larvae can be distinguished by their development of unusual pebbly skin when nearly full grown, pale yellow-green coloration, and dark stripe down the back. They feed during the summer and are rarely abundant enough to cause significant damage, although isolated outbreaks are reported. Trichiosoma triangulum2 is a related species that feeds on ash, birch, poplar, willow, and wild cherry. T. viminalis is common on willow and poplar in the Midwest.  Hymenoptera: Argidae; 2 Hymenoptera: Cimbicidae

1

A. Arge quidia, feeding

on northern red oak. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

B. Hollyhock sawfly larva. DAVID SHETLAR

C. Hollyhock sawfly adult. DAVID SHETLAR

D. Elm sawfly. HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

E. Elm sawfly adult. DAVID SHETLAR

F. Hibiscus sawfly larva. WHITNEY CRANSHAW

164

B C A D

E

F

INSECTS THAT CHEW ON LEAVES AND NEEDLES

PEARSLUG (PEAR SAWFLY, CHERRY SLUG) (Caliroa cerasi)1 hosts Sweet and ornamental varieties of cherry, plum, hawthorn, pear, and cotoneaster. Damage Larvae feed on the upper surface of leaves, producing distinctive skeletonizing wounds. Heavily damaged leaves turn brown and drop early. Distribution Throughout most of the northern half of the U.S. and southern Canada. Appearance Pearslug larvae are shiny and sluglike in general appearance but can be somewhat variable in color. Many are a dark olive green, but later instars tend to be lighter and may even have orange tones. Adults are shiny black stout-bodied wasps, about ⅓ inch long. Life History and Habits Adults emerge in late June or early July. Females insert their eggs singly in circular slits on the upper surface of leaves. Eggs hatch in about 2 weeks, and larvae chew small pits in the upper surface of leaves during early development. Later they more extensively chew the leaves but always avoid feeding on the larger veins and lower leaf surface, producing a typical skeletonizing injury pattern. When larvae are full grown they wander off the plant and dig a shallow cell in the soil to pupate. Pupation occurs in a small cocoon encrusted with soil particles. In about 2 weeks, many of the insects continue development and emerge as adults to produce a second generation. Larvae of these typically cause peak injury in early September. Populations of this second generation are usually smaller than those of the first generation, since many produced in the first generation remain dormant until the following spring. The full-grown larvae from the September generation drop to the soil and spin a cocoon in which they spend the winter. They pupate the following spring.

Other Slug Sawflies1 Larvae of roseslug (Endelomyia aethiops) are smooth and pale green, largely lacking the shiny moist surface of the pearslug. They feed as skeletonizers on the upper surface of rose leaves, typically leaving the lower epidermis intact, giving a windowpane appearance to leaves. Most injury is completed by late spring, and there is only one generation produced per year. Scarlet oak sawfly (Caliroa quercuscoccineae) develops on scarlet and pin oak, producing skeletonizing injuries to the lower leaf surface. Eggs are inserted into leaves; upon hatch the larvae migrate to the underside of the leaf. Younger larvae, which are pale green, feed gregariously, typically lined up next to each other. Older larvae turn green and they are solitary in the late stages. Two to three generations may occur annually, with damage most evident in late summer. Other oak-infesting slug sawflies include C. petiolata on pin oak; C. lobata on pin and black oak; C. fasciata on black, pin, and red oak; and C. obsoleta on white oak.  Hymenoptera: Tenthredinidae

1

166

A

B

D

E

C

F

A. Pearslug larvae and damage to pear.

of roseslug.

JIM KALISCH, UNIVERSITY OF NEBRASKA

DAVID SHETLAR

B. Adult pearslug.

F. Damage produced by

WHITNEY CRANSHAW

C. Young pearslug next

larvae of scarlet oak sawfly. JIM KALISCH, UNIVERSITY OF NEBRASKA

to egg scar.

G. Oakslugs.

WHITNEY CRANSHAW

DAVID SHETLAR

D. Roseslug larva. DAVID SHETLAR

G

E. Damage typical

INSECTS THAT CHEW ON LEAVES AND NEEDLES

TEXAS LEAFCUTTING ANT

(Atta texana)1

hosts A wide variety of plants, including grasses, small fruit, plum and peach, nut trees, certain ornamentals, and weeds. Damage Leafcutting ants remove plant buds and cut leaf fragments, causing potentially serious foliage loss. Young plants are at particular risk and may be entirely defoliated in a short period. Leafcutting ants may travel over 600 feet from the colony to locate forage. Distribution Western Louisiana, east to south-central Texas and northern Mexico. Appearance Leafcutting ant workers are rusty brown or dark brown. On close inspection they have three pairs of spines on the thorax and one pair on the head. Size varies considerably, from 1⁄16 to ½ inch long. Reproductive stages (males, potential queens) are larger and have dusky-colored wings. Life History and Habits Leafcutting ants are fungus gardeners. The leaf fragments they cut from plants are not eaten but instead used to cultivate a fungus that grows in special chambers deep in the colony. Parts of this fungus provide the sole food source of the leafcutting ant. Crater-shaped mounds around the nest entrance are external evidence of leafcutting ant colonies. These mounds may be from 5 to 14 inches high and 1 to 1½ feet in diameter. The belowground colony can be very large, extending 15–20 feet below the surface. Very large colonies may survive for several years and contain up to 2 million individuals. Winged reproductive forms emerge for mating flights on clear, moonless nights in late spring following heavy rains. Females that mate during this flight subsequently attempt to establish new colonies, with little chance of success. They carry with them a small packet of the essential fungus and will use it to establish fungal gardens. 1

Hymenoptera: Formicidae

LEAFCUTTER BEES

(Megachile spp.)1

hosts Many broadleaf plants, particularly rose, ash, lilac, and Virginia creeper. Damage Leafcutter bees do not eat plants, but adults do make smooth semicircular cuts along the edges of leaves and flowers. Damage is usually cosmetic, but serious defoliation is sometimes reported, particularly in desert areas of western states where isolated plantings of favorable plants are grown. Distribution Throughout North America, common. Approximately 140 native species occur in North America. Appearance Adults are usually black or gray and slightly smaller than a honey bee. Pollen is carried on hairs on the underside of the abdomen rather than in pollen baskets on the legs as in some other bees. Life History and Habits Winter is spent as a pupa in a cell lined with leaf fragments fastened together by the adult females. In late spring and early summer the adults emerge. Females seek natural hollows for nest sites or excavate tunnels in rotten wood or the pith of plant stems. They then create nest cells lined with pieces of cut leaves or flower petals. When complete, these somewhat resemble a cigar butt, and individual cells may involve more than two dozen leaf fragments cemented together. The nest cells are then packed with a mixture of pollen and nectar, and an egg is laid in each one. Larvae develop in the cells. One generation is produced per year.  Hymenoptera: Megachilidae

1

168

A B

C A. Texas leafcutting ants cutting leaf. SUSAN ELLIS, BUGWOOD.ORG

B. Texas leafcutting ants carrying leaf fragments. SUSAN ELLIS, BUGWOOD.ORG

C. Trail produced by Texas leafcutting ants. DAVID SHETLAR

D

D. Leafcutter bee damage to rose.

E

JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Drilled “bee board”

exposing nest cells produced by leafcutter bees. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Leafcutter bee cutting a leaf disk. DAVID SHETLAR

G. Larvae of leafcutter bees

exposed within nest cells.

F

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H. Leafcutter bee collecting nectar from sweet pea. WHITNEY CRANSHAW

I.Contents of nest cell

produced by a leafcutter bee. The large oblong object in the center is the cocoon within which a developing bee spends the winter. WHITNEY CRANSHAW

H

I

G

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF BEETLES Leaf beetles (Chrysomelidae family) are among the largest insect families in North America, containing about 1,500 species, several of which are serious plant pests. All species feed on plants in both adult and larval stages. Among the different species there is a wide range in the size of the adults (1⁄10 to nearly ½ inch), and most are oval or elongate oval in form. Many leaf beetles are brightly colored, others have banded or striped patterning. Larvae are varied in shape, with grub to sluglike, thin-elongate, and/or spiny larvae being common forms. Larvae can feed on plant foliage, mine leaves (page 218), or bore into roots (page 482).

Colorado Potato Beetle (Leptinotarsa decemlineata)1 hosts Colorado potato beetle is most common and damaging to potato but may also be found on eggplant, nicotiana, petunia, and certain nightshade weeds. Damage Both the adult beetles and the larvae chew on foliage. Notching wounds along the leaf margin are more typical of adults, whereas larvae produce more ragged injuries and may soil foliage with excrement. Although plants can usually tolerate low levels of leaf loss (at least 25%), extensive and damaging defoliation occurs during outbreaks. Colorado potato beetle is considered the most important potato insect pest worldwide, being very damaging throughout much of Europe. Management is often complicated by high levels of pesticide resistance that have developed in many populations. Distribution Colorado potato beetle has spread dramatically over the past 150 years, and it is now generally found east of the Rockies, excluding some areas around the Gulf of Mexico and the Maritime Provinces. It is most damaging in the eastern and central states. Appearance Adults are about ⅜ inch long, generally oval in shape and of convex body form. Alternating yellow and black stripes run along the back. Larvae are reddish or red-orange grubs with a dark head and some dark spotting. Colorado potato beetle produces masses of orange-yellow eggs that are somewhat similar to those of lady beetles but larger and darker in color. Other arthropods are sometimes confused with Colorado potato beetle. Certain blister beetles were sometimes known as “old-fashioned potato beetles” because they were conspicuous on potato before Colorado potato beetle was present. Pillbugs (page 530) are sometimes called “potato bugs” because of their habit of attacking potato starts that may get too wet in the spring. In some areas Jerusalem cricket (page 514) is also called a “potato bug.” Life History and Habits Colorado potato beetles winter in the adult stage under cover near plantings infested the previous season. They are capable of flying over moderate distances and move back to fields and gardens in late spring as potatoes and other susceptible plants emerge. Eggs begin to be laid in late spring as potatoes first emerge. The orange-red larvae feed on leaves, originally in groups but later dispersing individually throughout the plant. After becoming full grown, they drop from the plant and pupate in the soil. In about two weeks, adult beetles emerge and feed on plants. A second generation is typically produced in southern areas of the range; one generation predominates in the north. After feeding for a few weeks, adults disperse to overwintering sheltering areas and remain dormant until the following season. Related Insects In eastern North America the closely related false potato beetle (Leptinotarsa juncta) is present. Adults and larvae feed on horsenettle, ground cherry, and bittersweet, but not potato.

170

B C

A D

A. Colorado potato beetles. DAVID CAPPAERT

B. Colorado potato beetle

egg mass.

WHITNEY CRANSHAW

C. Colorado potato beetle

larvae hatching from eggs. WHITNEY CRANSHAW

D. Colorado potato beetle larvae. WHITNEY CRANSHAW

E

E. Damage to potato by

Colorado potato beetle. WHITNEY CRANSHAW

F. Pupa of the Colorado

potato beetle.

WHITNEY CRANSHAW

C2g False potato beetle,

Leptinotarsa juncta.

JOHNNY N. DELL, BUGWOOD.ORG

G. False potato beetle,

Leptinotarsa juncta.

JOHNNY N. DELL, BUGWOOD.ORG

F

G

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF BEETLES

Asparagus Beetle (Crioceris asparagi)1 hosts Asparagus. Damage Adult beetles chew pits in emerging spears, causing distortions of growth, and large numbers of the dark eggs may be laid on spears. Most injury, however, is caused by the larvae that chew the ferns, giving the plant a bleached appearance. Extreme infestations can reduce subsequent yields and sometimes even kill plants. Moderate asparagus beetle injury is tolerated by plants with little or no effect. Incidence of parasitism by the tiny eulophid wasp, Tetrastichus asparagi, is often very important in regulating abundance of asparagus beetle. Distribution This insect of European origin is most common in the Midwest and in states along the Atlantic Coast; however, it can now be found in Colorado, California, and Oregon. Appearance The adult beetle is about ¼ inch long, of general metallic blue-black color; however, it is also marked with yellowish square spots and has some red along the margins of the wing cover and prothorax. Larvae are generally gray with a dark head and rather sluglike in appearance. Life History and Habits Asparagus beetles overwinter in the adult stage around asparagus plantings. They become active in spring and fly to emerging spears and mate. The beetles chew on spears, and females lay upright dark eggs on the plant. Eggs hatch in about 1 week, and the gray, grublike larvae feed on the ferns. The larvae become full grown in about 2–3 weeks and drop to the soil to pupate. Adults emerge and repeat the cycle. Two or three generations are completed in a season, with some larvae present into September.

Related Species Spotted asparagus beetle (Crioceris duodecimpunctata)1 is often as common as asparagus beetle but is far less damaging to asparagus. The adult is bright orange with black spots. Larvae of this beetle develop in asparagus berries but do not damage the ferns, causing little injury. Minor chewing on ferns and spears is done by adults. Tomatillo leaf beetle (Lema trivittata)1 is widely distributed west of the Mississippi. Rarely seriously damaging, the grayish grublike larvae feed on leaves of various Physalis spp. nightshade family plants, particularly tomatillo and Chinese lantern. The larvae are further distinguished by their use of a “fecal shield,” created by piling moist feces on the back. Adults are generally yellow with some reddish markings and have distinct black stripes that give a fair resemblance to striped cucumber beetle and western corn rootworm. A very closely related species, Lema daturaphila, is also associated with nightshade family plants, particularly Datura spp. The taxonomy of the various Lema species is presently unsettled and major questions remain about the identity of the species present in North America and their host range. The red lily leaf beetle (Lilioceris lilii)1 is a European species that has become established in areas of the Northeast. It feeds on the foliage of true lilies (Lilium spp.) and Fritillaria spp. and can extensively defoliate plants. Adults are bright red with a black head and appendages and about ¼ to ⅜ inches long. The larvae are generally sluglike in appearance and cover themselves with their feces; their overall color is variable but they are most often orange or orange-brown and have a black head. Cereal leaf beetle (Oulema melanopus)1 is an accidentally introduced European species first detected in Michigan in 1962. Since then it has steadily increased its range and can be found in most states in the northern half of the U.S. Both adults and larvae feed on the leaves of grasses, with larvae producing extensive skeletonizing. Cereal leaf beetle is primarily a concern for small grain crops (e.g., wheat, rye, barley, oats), but some ornamental grasses found in gardens are also hosts. 172

B C

A E

D

H F

G

A. Asparagus beetles. WHITNEY CRANSHAW

B. Asparagus beetle eggs. WHITNEY CRANSHAW

C. Asparagus beetle damage. WHITNEY CRANSHAW

H

D. Asparagus beetle larvae.

I

WHITNEY CRANSHAW

E. Spotted asparagus beetle. WHITNEY CRANSHAW

F. Tomatillo leaf beetle. WHITNEY CRANSHAW

G. Larvae of the tomatillo leaf beetle. WHITNEY CRANSHAW

H. Tomatillo beetle larva. WHITNEY CRANSHAW

I. Red lily leaf beetle. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

J. Red lily leaf beetle eggs. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

K. Red lily leaf beetle larvae. TOM MURRAY

L. Cereal leaf beetle. DAVID SHETLAR

J

K

L

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF BEETLES

Striped Cucumber Beetle (Acalymma vittatum)1 hosts A wide variety of vegetables, although cucumber, melon, squash, and other cucurbits are preferred and most severely damaged. Damage Adult beetles feed on emergent seedlings and can retard development or even kill young plants. Later they may be found in large numbers in flowers of squash or melon and may chew pits in fruit. Larvae feed on the roots, causing little apparent injury, but may move into the rind of ripening melon fruit that rests on soil. Adult beetles can transmit a bacterium (Erwinia tracheiphila) that produces bacterial wilt in cucurbits. Striped cucumber beetle is also a vector of cucumber mosaic virus. Distribution Broadly distributed east of the Rockies. A closely related species, western striped cucumber beetle (A. trivittatum), is found in the Pacific States. The latter is yellowish orange with three black stripes and has a similar life history but is less often damaging. Appearance Adult beetles are about 1⁄5 inch long and bright yellow with three even, dark black stripes. The brighter yellow color, uniform width of the stripes, and presence of rows of minute indentations on the wing cover separate this insect from western corn rootworm, with which it is often confused. Life History and Habits Adult beetles spend winter under debris in the vicinity of gardens and fields. As temperatures warm in spring, they become active and feed on leaves and flowers (pollen) of several different trees and shrubs. When squash-family host plants emerge, the beetles move to these plants and chew seedlings. Eggs are laid in cracks around the base of the plants, and the hatching larvae feed on the roots for about a month. They then pupate in the soil, later emerging as adult beetles. There typically are two generations per season, but this can range from one to three depending on location and weather.

Related Species Diabrotica undecimpunctata howardi,1 known as both spotted cucumber beetle and southern corn rootworm, feeds on a very wide range of plants, notably cucurbits and corn. Adults may be found in almost any type of flower. Most damage is done by adults that chew on flowers, foliage, and rinds of ripening fruit. Larvae may tunnel roots and can stunt plants and sometimes kill seedlings. It occurs east of the Rockies and ranges deep into Mexico. In the Pacific States a subspecies occurs known as western spotted cucumber beetle (D. u. undecimpunctata). 1

Coleoptera: Chrysomelidae

174

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F

B E

G A. Striped cucumber beetles. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

B. Seedling damage by striped cucumber beetle. WHITNEY CRANSHAW

C. Bacterial wilt symptoms

in pumpkin.

H

JIM JASINSKI, OHIO STATE UNIVERSITY EXTENSION, BUGWOOD.ORG

D. Striped cucumber beetle larva underneath melon.

I

WHITNEY CRANSHAW

E. Larval tunneling injury

in base of squash. WHITNEY CRANSHAW

F. Striped cucumber beetles, and one western corn rootworm, in discarded melon. WHITNEY CRANSHAW

G. Mating pair of western

striped cucumber beetles. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J

H. Spotted cucumber beetle/southern corn rootworm. WHITNEY CRANSHAW

I. Western spotted

cucumber beetle. WHITNEY CRANSHAW

J. Spotted cucumber

beetle and striped cucumber beetle on squash fruit. WHITNEY CRANSHAW

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF BEETLES In most areas, winter is usually spent in the adult stage in plant debris and particularly among plants that have not been completely killed by frosts. Spotted cucumber beetle may be active year-round in warmer climates, whereas in northern areas it may die out and infestations may result from migration from southern states during the growing season. Adults feed on pollen, corn silks, tender foliage, and other plant parts. Eggs are laid in soil cracks near seedlings of host plants in the spring, and larvae feed on roots for about 1 month. One to three generations may be produced during a growing season, but they overlap considerably and are difficult to distinguish. Two other insects are also known as “corn rootworms”: the western corn rootworm (Diabrotica virgifera virgifera) and the northern corn rootworm (D. barberi). Both are primarily important in the larval stage (page 482), which feeds on the roots of corn, and they are the most important insect pests of field corn grown in the Corn Belt states. Adults, which are present throughout summer, can be found feeding primarily on leaves and silk of corn and on pollen and flowers of squash family plants. Incidental damage may also occur on leaves of a wide range of other plants, particularly leafy vegetables. Banded cucumber beetle (D. balteata) is originally from the southwestern U.S. and Mexico but has extended its range throughout the southern U.S. Adults feed on foliage and flowers of a wide range of vegetables. Larvae chew roots. Squash, melon, bean, and some crucifers are commonly damaged. Larval injury may also be severe in tubers of sweetpotato. The life history is similar to that of spotted cucumber beetle, and there can be nearly continual breeding in areas of warm climate. Also found feeding on various squash family plants in the southwestern states is the checkered melon beetle (Paranapiacaba tricincta),1 a colorful leaf beetle with black and white spotting. Large masses of adults can sometimes seriously damage young plants of squash and melons, with honeydew being particularly susceptible to injury.

OTHER LEAF BEETLE DEFOLIATORS Red turnip beetle (Entomoscelis americana)1 can be a common vegetable garden pest in the northwestern U.S. and western Canada. In spring it feeds on most of the crucifers, including cabbage, broccoli, mustard, radish, watercress, and horseradish, and it can be damaging in both larval and adult stages. Larvae hatch from overwintered eggs and chew foliage, stems, and cotyledons of seedlings and young plants. Pupation occurs in the soil, and the adults may also feed on foliage for a brief period before undergoing a period of summer dormancy. Adults become active again in late summer, feed on foliage of crucifers, and lay eggs, which are the wintering stage. Yellowmargined leaf beetle (Microtheca ochroloma)1 feeds on crucifers in some of the Gulf States. Both adults and larvae feed on foliage during spring. Only a single generation appears to be produced, with overwintered adults moving to plants in spring and laying eggs on the leaves. The life history of this introduced species is poorly understood in the U.S., but adults appear to go through a period of dormancy during the summer months. Sweetpotato leaf beetle (Typophorus nigritus)1 occurs in most of the southeastern U.S. Adults feed on foliage of sweetpotato and morning glory, often in groups, and cause some localized defoliation; however, most damage to sweetpotato is produced by the larvae, which develop on the roots and stems. They may burrow deeply into the sweetpotato tubers or limit feeding to scarring of the surface. One generation is produced, with adults emerging from their overwintering pupal cells beginning in late May and early June.

176

A C D

B E

F

A. Two western corn rootworms on squash blossom. WHITNEY CRANSHAW

B. Western corn rootworm

leaf feeding injury to corn leaf. DAVID KEITH, UNIVERSITY OF NEBRASKA

C. Comparison of western

corn rootworm (left, center) and striped cucumber beetle. WHITNEY CRANSHAW

D. Comparison of western corn rootworm

and northern corn rootworm. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Checkered melon beetles damaging

honeydew.

WHITNEY CRANSHAW

F. Banded cucumber beetle. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

G H

G. Yellowmargined leaf beetle. JOHN CAPINERA, UNIVERSITY OF FLORIDA

H. Yellowmargined leaf beetle larva. JOHN CAPINERA, UNIVERSITY OF FLORIDA

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF BEETLES Bean leaf beetle (Ceratoma trifucata)1 is common in the eastern U.S. It feeds on a wide variety of legumes and is most damaging to soybean but will damage garden beans, although it is far less common than Mexican bean beetle. It is particularly abundant on early planted beans, and adults may cause serious defoliation of small plantings. Larvae develop on the roots of beans but apparently cause little injury. Two or three generations may occur annually. Sunflower beetle (Zygogramma exclamationis)1 is a common insect associated with sunflower in parts of the Midwest and High Plains. Adults are somewhat similar to Colorado potato beetle in shape and patterning, although a bit smaller. Sunflower beetle larvae, which are pale green and grublike, feed on the leaves of sunflower and some related plants. Milkweed leaf beetle  (Labidomera clivicollis)1 feeds on the leaves and sometimes the flowers of milkweeds. The bright orange and black markings of the adults somewhat resemble those of lady beetles. Eggs are laid on leaves and the plump-bodied larvae feed for a few weeks until full grown, when they drop to the ground and pupate in the soil. Two generations are produced annually. Dogbane beetle (Chrysochus auratus)1 is a brilliantly colored, iridescent beetle associated with dogbane (Apocynum spp.), uncommonly found on a few other broadleaf plants. It is not considered a pest species but often attracts attention because of its vivid coloration and moderately large size (⅓–½ inch). Larvae develop on the roots of dogbane. Dogbane beetle is widely distributed east of the Rocky Mountains. The rubber rabbitbrush beetle (Trirhabda nitidicollis)1 is an early season defoliator of Ericameria nauseosa in the western U.S. Winter is spent as eggs laid in small masses in the soil, and they are stimulated to hatch by spring rains associated with production of new growth. The larvae climb the plant to feed on leaves, and they are an unusual metallic dark blue color. Pupation occurs in the soil and later the adults emerge, feed for a brief period, then lay the overwintering eggs. Other Trirhabda in the western U.S. are associated with yellow rabbitbrush, big sagebrush, coyote brush, and brittlebush. In eastern North America Trirhabda spp. are most often observed associated with goldenrods. At least five goldenrod-feeding species occur, with T. virgata often the most commonly observed species in the Mid-Atlantic States. T. bacharidis commonly defoliates eastern baccharis (sea or salt myrtle) in Gulf States. Strawberry rootworm (Paria fragariae)1 is a common insect associated with strawberry, and less commonly blueberry, in much of eastern North America and California. Larvae feed on roots, but most damage is in the form of leaf chewing by adults, which feed at night. Feeding injuries may conspicuously riddle leaves, although effects on plant growth are usually minor. Adult beetles are about ⅛ inch long and shiny black, with four light patches on the wing covers. They emerge from overwintering cover in spring and alternate between feeding and egg-laying at this time. Larvae develop during late spring and early summer. Adults are present again in late summer and also feed at this time before moving to winter shelters. Adults of cranberry rootworm (Rhabdopterus picipes)1 produce conspicuous feeding injuries to rhododendron, camellia, photinia, and other shrubs. They feed at night on the emerging leaves, causing elongated, often crescent-shaped feeding holes in the mature leaves. Larvae develop on the roots of cranberry and blueberry but rarely cause much injury. Damage by cranberry rootworm. 1

Coleoptera: Chrysomelidae

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SYSTEM, BUGWOOD.ORG

178

A

B D

C E

F

G

H

A. Bean leaf beetle. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Bean leaf

beetle damage. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Sunflower

I

beetle.

J

WHITNEY CRANSHAW

D. Sunflower

beetle larva.

WHITNEY CRANSHAW

I. Larva of the rubber

rabbitbrush beetle. WHITNEY CRANSHAW

J. Larva of the

goldenrod leaf beetle. DAVID SHETLAR

K. Strawberry

WHITNEY CRANSHAW

rootworm adult.

E. Milkweed

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SYSTEM, BUGWOOD.ORG

TOM MURRAY

L. Damage by

leaf beetle.

K

H. Rubber rabbitbrush beetle.

F. Milkweed

leaf beetle larva. DAVID SHETLAR

G. Dogbane leaf

beetles.

DAVID SHETLAR

strawberry rootworm.

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SYSTEM, BUGWOOD.ORG

M. Goldenrod leaf beetle. DAVID SHETLAR

L M

INSECTS THAT CHEW ON LEAVES AND NEEDLES

TORTOISE BEETLES Tortoise beetles are a subfamily (Cassidinae) of the leaf beetles. Adults have a broad body form and are sometimes mistaken for lady beetles; some can produce brilliant metallic coloration. Larvae are rather flattened and spiny but most are marked by their habit of carrying a shield of old cast skins and feces attached to the tip of the abdomen but covering much of the body. Adults characteristically chew large holes in the interior of leaves; larvae skeletonize leaves.

Golden Tortoise Beetle (Charidotella sexpunctata)1 hosts Morning glory, sweetpotato, field bindweed, and related plants in the morning-glory family (Convulvulaceae). Damage Adults and larvae feed on foliage, producing shothole-type wounds in the leaf interior. Damage is insignificant for plant health, but the unusual appearance of the insects and the leaf riddling they produce may attract attention. Distribution Tortoise beetles are most common in the eastern U.S., particularly the southeast. Several species have ranges extending to the Rocky Mountains, Texas, and into Mexico. Appearance Adults are generally oval, somewhat flattened, with the head tucked under the shield of the prothorax; however, what attracts attention is their bright metallic gold coloration. Because of this feature they are sometimes mistaken for golden lady beetles and have also been known as “gold bugs.” Larvae are generally flattened and spiny but are shielded on top by their old cast skins and feces, so they look gray, brown, or black when viewed from above. Life History and Habits Tortoise beetles winter as adults, emerging in late spring when they begin to feed on leaves. Females subsequently lay eggs, in a series of small clusters, on the underside of leaves. Immature stages chew the underside of leaves. Upon molting they subsequently carry the previous cast skin, held by a pair of movable forked spines on the hind end. The skins, plus feces, create a shield that arches over the body. The habit of carrying this debris on their backs, common among tortoise beetles, leads to their sometimes being called “peddlers.” Larval development is completed within a month. Pupation occurs on leaves and stems to which they attach by the hind end. The pupae are dark colored, somewhat spiny, and often still covered with debris. Adults emerge in 7–10 days and feed on leaves for a short while before going into dormancy. Although relatively little is known about the life history, one generation per year seems normal. The bright coloration of this insect is what attracts most attention. The coloration can vary depending on angle of view, being brightest when viewed from above and more reddish brown from a side angle. Coloration also varies depending on condition of the beetle, which can rapidly lose much of its reflection when disturbed. This effect is achieved by differences in the hydration of the exoskeleton, which is largely translucent but constructed of minute channels that can carry moisture. When hydrated, the grooves cause the exoskeleton to reflect light in a mirror-like fashion, producing the brilliant metallic coloration. The underlying darker pigments become exposed when the insect reduces movement of water into the surface channels of the exoskeleton, or when it dies.

180

B

C

D

A E

A. Golden tortoise beetles on bindweed leaf.

F

WHITNEY CRANSHAW

B. Golden tortoise beetle. DAVID SHETLAR

C. Late-instar larva of the

golden tortoise beetle. WHITNEY CRANSHAW

D. Young larva of the golden tortoise beetle. WHITNEY CRANSHAW

E. Mottled tortoise beetle. DAVID SHETLAR

F. Argus tortoise beetle. DAVID SHETLAR

Other Common Tortoise Beetles Several other tortoise beetles are associated with morning-glory family plants. The mottled tortoise beetle (Deloyala guttata)1 also has extensive areas of metallic gold coloration but is more extensively patterned with black than the golden tortoise beetle. Four broad dark stripes on the wings are characteristic of the striped tortoise beetle (Agrioconota bivittata),1 which also can show reflected metallic coloration. The blacklegged tortoise beetle (Jonthonota nigripes)1 is more generally reddish or brown, with black spotting. More extensive black spotting is present on the Argus tortoise beetle (Chelymorpha cassidea),1 which is primarily yellow or orange-brown. Chelymorpha cribraria is a species recently established in southern Florida that can show wide range in coloration.

181

INSECTS THAT CHEW ON LEAVES AND NEEDLES

TORTOISE BEETLES, AND CASE-BEARING LEAF BEETLES Eggplant tortoise beetle (Gratiana pallidula)1 is found throughout the eastern U.S. but is abundant only in the southern states. It often has spotted or striped markings. It makes small holes in the foliage of eggplant, potato, and various nightshade family weeds but does not cause serious injury. Clavate tortoise beetle (Plagiometriona clavata) also develops on nightshade family plants. Sunflower tortoise beetle (Physonota helianthi) develops on sunflowers in the midwestern and northeastern states. Palmetto tortoise beetle, Hemisphaerota cyanea,1 is found in coastal areas of the southeastern U.S. to Texas, where it feeds on foliage of Washington palms. It is dark gun-metal blue to purple and about 3⁄16 inch in length. The yellowish-white larvae have conspicuous projections along the sides and cover themselves with fecal matter. The thistle tortoise beetle (Cassida rubiginosa)1 is a green-colored beetle that feeds on leaves of Canada thistle, sometimes causing extensive defoliation. It is a European species that was purposely introduced in Virginia as a potential biological control of Canada thistle and has subsequently spread widely (sometimes with intentional human assistance) so that it can be found throughout much of North America where its host plant is present. 1

Coleoptera: Chrysomelidae (Cassidinae)

CASE-BEARING LEAF BEETLES Sycamore leaf beetle (Neochlamisus platani)1 feeds on foliage of American sycamore in both the adult and larval stages. River birch, hazel, and elm are additional, but infrequent, host plants. Eggs are laid singly on leaves and covered by a bit of fecal material. Upon hatch the larvae feed on leaves and almost immediately begin constructing a case that covers the abdomen. This case is constructed primarily of feces produced by the insect, mixed with some plant material, and it tapers at the tip. The larvae expand the case as they grow and feed on all of the leaf except for major veins. Pupation also occurs in the case, which is often attached to twigs and resembles a bud. Adults emerge in summer, feed for a period, and then move to winter shelter. Adults, a type of “warty leaf beetle,” are small, bronze to reddish-bronze beetles of irregular rounded body form, somewhat resembling a caterpillar dropping. At least 17 Neochlamisus species occur in North America, almost all of which occur east of the Rocky Mountains. Most are quite host specific: blueberry casebeetle (N. cribripennis) feeds on native lowland blueberry in eastern Canada and the northeastern U.S., whereas caneberries (Rubus spp.) host N. bimaculatus. Within the genus, N. bebbianae is unusual in having a fairly wide host range that includes specific plants that occur in five plant families. In addition, there are nine species of North American warty leaf beetles in the genus Exema that develop on aster family plants. 1

Coleoptera: Chrysomelidae

182

A

B

C

D

E

F

A. Clavate tortoise beetle larva. TOM MURRAY

B. Clavate tortoise beetle. TOM MURRAY

C. Sunflower tortoise beetle. TOM MURRAY

G H

I

D. Sunflower tortoise beetle larva. TOM MURRAY

E. Thistle tortoise beetle. WHITNEY CRANSHAW

F.Palmetto tortoise beetle. JOHNNY H. DELL, BUGWOOD.ORG

G. Thistle tortoise beetle larva. WHITNEY CRANSHAW

H. Thistle tortoise beetle pupa. WHITNEY CRANSHAW

I. Thistle tortoise beetle egg mass. WHITNEY CRANSHAW

J

l m

K

J. Larva of a case bearer

beetle, Neochlamisus sp. TOM MURRAY

K. A “warty leaf beetle,”

Neochlamisus bebbianae. TOM MURRAY

L. Pupa of a case bearer

beetle, Neochlamisus sp. TOM MURRAY

M. Larva of a case bearer beetle. DAVID SHETLAR

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF BEETLES THAT SKELETONIZE LEAVES Elm leaf beetle (Xanthogaleruca luteola)1 feeds on the leaves of various elms (Ulmus). Adults chew large shotholes in leaves and larvae develop as skeletonizers of the lower leaf surface. It is generally found throughout North America wherever elm hosts are grown, but in recent years populations have declined in many areas across the central U.S. Winter is spent in the adult stage in protected areas, including nearby buildings. During this period the adults are in reproductive diapause and a dark khaki-green color. In late April and early May the beetles emerge and move to elm trees to feed and mate, and coloration changes to a yellow-green. After a period of several weeks, females begin to lay masses of bright yellow eggs, typically attached to veins on the lower leaves. Larvae hatch after about 10–14 days and feed for about 3 weeks, molting three times in the course of development. Larvae are generally black, developing some yellow striping in later stages, and feed primarily on the underside of leaves. They then crawl down the tree trunk in search of pupation Elm leaf beetle prepupae and pupae at base of tree. sites. Most work their way to the base of the tree to pupate WHITNEY CRANSHAW at the base, but some may rest in folds of bark furrows. Adults emerge in about 10–15 days, and in most areas of the U.S. there is a second generation. In northern areas the beetles may feed briefly and then move to winter shelter, deferring reproduction to the next season. Larger elm leaf beetle (Monocesta coryli)1 is one of largest leaf beetles in North America, about ½ inch in length. Much less damaging to elm than elm leaf beetle, it also feeds on foliage. It is currently found from Pennsylvania to Florida and west to Kansas.

above: Elm leaf beetle eggs. WHITNEY CRANSHAW

right: Elm leaf beetle larvae at egg hatch. WHITNEY CRANSHAW

184

A

B C

D E

F

A. Elm leaf beetle larvae and injury. WHITNEY CRANSHAW

B. Elm leaf beetle adult, summer coloration. WHITNEY CRANSHAW

C. Elm leaf beetle larvae. WHITNEY CRANSHAW

D. Elm leaf beetle adult with dormant season

coloration.

JOSEPH BERGER, BUGWOOD.ORG

E. Larvae of the larger elm leaf beetle. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

F. Larger elm leaf beetle. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF BEETLES THAT SKELETONIZE LEAVES Viburnum leaf beetle (Pyrrhalta viburni)1 is a European species recently introduced into North America and currently found in New York, northern New England, and Ontario south to central Pennsylvania and Ohio. Larvae and adults feed on leaves of several types of viburnum and have been very damaging to some species; other viburnum species show resistance. Winter is spent as eggs glued into pits chewed in small twigs. Larvae hatch in early May and initially feed in groups, skeletonizing the lower leaf surface. Older larvae feed more generally. Adults, which appear similar to drab-colored elm leaf beetles, appear in July and are present through September. Adult feeding produces oblong holes in the interior of leaves. One generation is produced annually. Imported willow leaf beetle (Plagiodera versi­ color)1 is a small species of leaf beetle (ca. ⅛ inch), metallic black to dark greenish blue. Eggs are laid in clusters on willow, above: Viburnum leaf beetle adult. DAVID SHETLAR particularly black and white willows. The young larvae feed as a below: Imported willow leaf group, skeletonizing the underside of leaves. Older larvae beetle larvae and damage. DAVID SHETLAR disperse, and adults may chew small holes in leaves. Two to three generations may occur through the range, which currently extends from New England to Virginia and west to Michigan. Pacific willow leaf beetle (Tricholochmaea decora carbo)1 develops on willow, poplar, and alder in the Pacific Northwest. Adults closely resemble elm leaf beetle but are dull black. A grayish or yellow-brown subspecies (T. d. decora) is present in the Prairie Provinces. The flea beetle Altica suplicata occurs on willow in the Rocky Mountain region. Cottonwood leaf beetle (Chrysomela scripta)1 is found throughout much of North America and can be very damaging to cottonwood and poplar, particularly in the midwestern states. During early stages, larvae feed in groups and produce ragged skeletonizing injuries; later they feed more generally on leaves. Succulent new growth is favored. Adults feed on tender twigs and also skeletonize leaves, but they do much less damage than the larvae. Cottonwood leaf beetle is a light tan, oval beetle about ⅜ inch long marked with elongate black spots. Widely distributed in North America, it is most common in the northern U.S. and southern Canada. Cottonwood leaf beetles winter as adults, scattered around previously infested trees in protected locations such as under leaf litter or clumps of grass. Shortly after leaves emerge, the adults begin to move back to trees and feed. After a few weeks females begin to lay eggs, which are deposited in clusters of a few dozen or more, on the undersurface of leaves. The larvae are first yellow then black and grublike, with whitish spotting appearing as they age. When disturbed they can produce defensive chemicals that ooze from the light-colored glands on the body. Cottonwood leaf beetles pupate attached to the leaf, the old larval skin conspicuously present at the base of the black pupa. Adults from this first generation emerge in early summer and produce a second generation. 186

A

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C D

E

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G

H

A. Viburnum leaf beetle larvae and damage. DAVID SHETLAR

B. Viburnum leaf beetle egg masses on twig. DAVID SHETLAR

C. Defoliation produced by viburnum leaf beetle. DAVID SHETLAR

D. Imported willow leaf beetle. DAVID CAPPAERT, BUGWOOD.ORG

I

E. Imported willow leaf beetle larvae. WHITNEY CRANSHAW

F. Cottonwood leaf beetle larvae. WHITNEY CRANSHAW

G. Cottonwood leaf beetle larvae. DAVID LEATHERMAN

H. Cottonwood leaf beetle egg mass. WHITNEY CRANSHAW

I. Cottonwood leaf beetle larvae at egg hatch. WHITNEY CRANSHAW

J. Cottonwood leaf beetle pupae. WHITNEY CRANSHAW

J

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF BEETLES THAT SKELETONIZE LEAVES, AND LEAF BEETLES OF AQUATIC PLANTS Chrysomela knabi (Knab’s leaf beetle) produces similar injuries primarily to willow and is found throughout much of North America. Adults are highly variable in both coloration and patterning. Chrysomela aenicollis also develops on willow as well as aspen but has a much more restricted distribution within parts of the western U.S. and Canada. Elm calligrapha (Calligrapha scalaris),1 sometimes known as the “linden leaf beetle,” feeds on foliage of elm, linden, alder, and willow in areas of the Midwest and Northeast. Several other common species develop on willows and C. philadelphica on dogwood. Coreopsis beetle (C. californica coreopsivora)2 skeletonizes foliage of coreopsis and ambrosia. 1

Coleoptera: Chrysomelidae

LEAF BEETLES OF AQUATIC PLANTS Waterlily leaf beetle (Xanthogaleruca nymphaeae)1 is associated with water lilies particularly yellow water lily, in eastern North America. Both larvae and adults feed on the upper leaf surface of floating lily leaves. Injuries by the insect also provide entry for leaf pathogens, contributing to decay. The overwintering stage is an adult that spends winter under protective debris in the vicinity of ponds. Adults are dark brown to yellow brown with a yellow underside. They become active in late spring and lay masses of eggs on the upper leaf surface. Eggs hatch in 4–5 days, and subsequent larval development is rapid, being completed in about 9 days. Younger larvae usually feed in small groups and skeletonize leaf surfaces. Older larvae chew holes in leaves. Pupation occurs on the leaf surface, and the pupal stage takes about 5 days to complete. In South Carolina, continual overlapping generations are produced into October. Another common beetle associated with yellow water lily in the eastern U.S. is Donacia piscatrix,1 a type of “false longhorn beetle.” Damage is caused by the larvae, which are adapted to aquatic life. They feed on the underwater stems and petioles, deriving oxygen from a special spiracle on the end of the body that is inserted into the plant stems. Pupation also occurs in water. Adults are bronzy colored beetles, about ¼ inch long. One generation is produced annually. About 30 Donacia species are present in North America, most found in the northeastern U.S. and southeastern Canada. All feed on water lilies in the genera Nymphaea, Brasenia, and/or Nuphar. Another closely related group of leaf beetles are in the genus Plateumaris, representing 17 North American species. Host plants of these aquatic leaf beetles include Acorus, Carex, Eleocharis, Phragmites, Scirpus, Juncus, Caltha, and Iris versicolor. 1

Coleoptera: Chrysomelidae

188

A. Knab’s leaf beetle. WHITNEY CRANSHAW

B. Larvae of Knab’s leaf beetle. WHITNEY CRANSHAW

C. Calligrapha beetle associated

with willow.

SUSAN ELLIS, BUGWOOD.ORG

A

D. Calligrapha beetle associated

B

with dogwood.

C D

BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

E. Coreopsis beetle. ROBIN ROSETTA, OREGON STATE UNIVERSITY

E

F

G

H

F. Waterlily leaf beetle. TOM MURRAY

G. A Donacia species of

false longhorn leaf beetle associated with waterlily. TOM MURRAY

H. Mating pair of a

Plateumaris species of leaf beetle. TOM MURRAY

INSECTS THAT CHEW ON LEAVES AND NEEDLES

FLEA BEETLES Flea beetles are a subfamily (Alticinae) of the leaf beetles. Many are among the smallest of the beetles that feed on leaves, typically 1⁄15 to 1⁄6 inch. Characteristically they possess very large rear legs that enable them to jump, and the combination of small size and jumping ability lends them their name. Many flea beetles are uniformly metallic colored; others may have stripes or spots. Several species are commonly encountered in yards and gardens and a few are important plant pests. There are two general patterns of life history among the flea beetles. Adults of all feed on foliage, but the larvae of some species are also leaf feeders; these include the larger flea beetles. Plant injury produced is typical of that produced by other leaf beetles: a generalized defoliation or feeding in a skeletonizing pattern. Most flea beetles have larval stages that develop on plant roots. These are small beetles, and the most conspicuous injuries are produced by adults which chew small pits in leaves (shotholes).

Flea Beetles with Larvae that Develop on Foliage A few flea beetles, including some of the largest species, develop on foliage. Eggs are laid in masses on the leaves, and young larvae often feed gregariously, producing skeletonizing injuries typical of many other leaf beetles. Older larvae and adults chew larger holes in foliage. Probably the most commonly encountered of these flea beetles with larvae that feed on foliage are the various “spinach flea beetles” of the genus Disonycha.1 Three species occur in the U.S, spinach flea beetle (D. xanthomelas), threespotted flea beetle (D. triangularis), and yellownecked flea beetle (D. mellicollis), and they are all about ¼ inch long. Eggs are laid in small groups on leaves and stems of host plants, and the larvae initially feed gregariously. As they get older, they disperse throughout the plant and produce a generalized defoliation. A wide range of plants are hosts, and many weedy plants, notably pigweeds and lambsquarters, are much more commonly damaged than spinach. In addition, there are more than two Larva and feeding damage dozen other Disonycha species, many of which with prominent striping. Some by spinach flea beetle. chew on leaves of perennial plants such as willow and penstemon, but the WHITNEY CRANSHAW majority feed on herbaceous annuals, including many common weedy hosts. Shiny metallic flea beetles found on various trees and shrubs are in the genera Macrohaltica and Altica. Grape flea beetle (Altica chalybea)1 is found throughout the eastern U.S. on grape, Virginia creeper, apple, beech, elm, and plum. Buds are tunneled by adults of the first generation, causing the most damage. Later in the season leaves are skeletonized by larvae. A. litigata is an occasional leaf-chewing pest of crape myrtle and evening primrose in the southern states. Evening primrose and strawberry are hosts for strawberry flea beetle (A. ignata) in the eastern U.S., and willow is the host of A. bimarginata in the west. Apple flea beetle (A. foliacea) is a metallic bright green or shiny blue species found throughout most of North America. Adults and larvae feed on the foliage of apple, crabapple, grape, evening primrose, willow, Gaura, rose, sedum, and fuchsia. In the southwest, steel-blue grapevine flea beetle (A. torquata) feeds on grape and evening primrose. Alder flea beetle (Macrohaltica ambiens) is a transcontinental species associated with alder. 190

A. Spinach flea beetle. WHITNEY CRANSHAW

B. Threespotted

flea beetle.

WHITNEY CRANSHAW

C. A Disonycha species

A

associated with willow. WHITNEY CRANSHAW

D. Grape flea beetle.

B

DAVID SHETLAR

E. Apple flea beetles. WHITNEY CRANSHAW

F. Egg mass of the

apple flea beetle. WHITNEY CRANSHAW

G. Apple flea beetle

larvae on evening primrose. WHITNEY CRANSHAW

H. Apple flea beetles

on evening primrose. WHITNEY CRANSHAW

I. Alder flea beetle. WHITNEY CRANSHAW

J. Alder flea beetle

larvae and damage.

C

D

E

F

G H

I

J

KENNETH R. GIBSON, USDA-FOREST SERVICE, BUGWOOD.ORG

INSECTS THAT CHEW ON LEAVES AND NEEDLES

FLEA BEETLES Sumac flea beetle (Blepharida rhois) is a rather large species common in northern areas east of the Rockies. Adults have striped patterning and a general shape similar to that of a small Colorado potato beetle. They develop on Rhus (sumac, skunkbrush).  Coleoptera: Chrysomelidae (Alticinae)

1

Crucifer Flea Beetle (Phyllotreta cruciferae)1 hosts Virtually all members of the mustard family (Brassicaceae). This includes cabbage, turnip, cauliflower, kale, Brussel sprouts, horseradish, radish, and canola Damage Crucifer flea beetles make shotholes wounds in leaves of host plants. In high populations they can kill seedlings and seriously affect quality of plants, particularly those produced for leaves (e.g., Chinese cabbage, mustard greens, arugula). The larvae feed on the roots of host plants which can cause minor to severe stunting of growth. Distribution Crucifer flea beetle is a non-native species accidentally introduced from Europe in the 1920s and now common across Canada and northern North America. Appearance Adults are small black beetles, 1⁄32–⅛ inch long, with a distinctive metallic blue sheen. Like most flea beetles, this species quickly jumps when approached or disturbed. The larvae are about ⅛ inch long, wormlike and cream colored. Life History and Habits Successfully wintered adults emerge from leaf litter and grassy areas when temperatures first begin to reach 60° F. These adults feed on leaves of wild mustard and other cruciferous plants. By June, host plants and soil temperatures are suitable for females to lay eggs. The females lay eggs until July in the soil around potential host plants. Eggs take two weeks to hatch, and the larvae quickly dig into the soil to feed on the roots of cruciferous plants. Larvae take 25–30 days to complete development, then form a pupa in a soil cell. A week or so later, the new adults begin to emerge. These continue feeding on host leaves until fall weather coaxes the adults to find shelter. One generation is completed per year.

Other Flea Beetles with Larvae that Feed on Roots Cabbage family plants host several additional flea beetles in the genus Phyllotreta, some of which can be extremely damaging, particularly to seedlings. Western black flea beetle (P. pusilla) is a small, shiny black species that is injurious to a wide range of crucifers throughout much of the western half of the northern U.S. and southern Canada. It has a considerably wider host range than other members of this genus and is also found on other vegetables such as beet, potato, and lettuce. Other members of this genus are generally pale brown with dark striping of some pattern. These include western striped flea beetle (P. ramosa) in California, horseradish flea beetle (P. armoraciae), and striped flea beetle (P. striolata).

192

A

B C. Sumac flea beetle larvae.

A. Sumac flea beetle.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

B. Sumac flea beetle egg masses.

C

WHITNEY CRANSHAW

D

E

F

G

H

D. Crucifer flea beetle. JEFF HAHN, UNIVERSITY OF MINNESOTA

E. Western black flea beetle

on broccoli.

I

WHITNEY CRANSHAW

F. Western black flea beetle

damage to Chinese cabbage. WHITNEY CRANSHAW

G. Western black flea beetle

damage to seedling kohlrabi. WHITNEY CRANSHAW

H. Western black flea beetle larva. WHITNEY CRANSHAW

I. Horseradish flea beetle. WHITNEY CRANSHAW

J. Striped flea beetle and

crucifer flea beetle. DAVID SHETLAR

J

INSECTS THAT CHEW ON LEAVES AND NEEDLES

FLEA BEETLES Several flea beetles in the genus Epitrix1 are associated with nightshade family plants. They are among the smallest flea beetles (1⁄16 inch) and uniformly colored from black to dark brown. Most widespread is the potato flea beetle (E. cucumeris), which very commonly produces shothole injuries to potato and tomato. Others of similar appearance but with more western distribution include western potato flea beetle (E. subcrinita) and tuber flea beetle (E. tuberis). The latter species is also damaging in the larval stage as it will tunnel into tubers. Tobacco flea beetle (E. hirtipennis) commonly above: Western potato feeds on eggplant, tobacco, and potato. It has bronze coloration and is predominant flea beetle. KEN GRAY COLLECTION, in the southern half of the U.S. In much of the eastern U.S., eggplant is also a OREGON STATE UNIVERSITY favored host of eggplant flea beetle (E. fuscula). below: Tobacco flea beetle. RUSS OTTENS, UNIVERSITY Also among the smallest flea beetles are Chaetocnema species.1 Most feed OF GEORGIA, BUGWOOD.ORG strictly on grasses, and corn flea beetle (C. pulicaria) is an important species in parts of the Midwest, where it may transmit the bacteria that produce the disease Stewart’s wilt of corn. Toothed flea beetle (C. denticulata) also occurs in the midwestern and northeastern states on corn and other grasses. Sweetpotato flea beetle (C. confinis) is a common species, particularly in the southern U.S., where it develops on sweetpotato, dichondra, morning glory, and raspberry. In southern California dichondra flea beetle (C. repens) can be a pest where dichondra is grown as a groundcover and in lawns. Adults cut small crescent-shaped holes in leaves. More damage is done by larvae, which feed on roots and burrow into the crown of the plants, causing wilting and even death. Striping is also found among flea beetles in the genus Systena,1 which tend to be slightly larger species (⅛ inch). Palestriped flea beetle (S. blanda) is not only one of the most widely distributed flea beetles of North America but has the broadest host range. It commonly damages squash family plants, bean, corn, sunflower, lettuce, potato, and many weeds. Closely resembling it is elongate flea beetle (S. elongata) which overlaps considerably in geographic range and host range. Redheaded flea beetle (S. frontalis) is common in the areas of the midwestern and Mid-Atlantic States. It has a very wide host range that includes cabbage, bean, beet, corn, potato, forsythia, dogwood, sedums, zinnia, Elongate flea beetle. KEN GRAY COLLECTION, hibiscus, aster, as well as several common weeds such as smartweed, lambsquarters, OREGON STATE UNIVERSITY 1 and pigweeds. Adults are about ⁄6 inch long and black with a reddish-yellow head. Hop flea beetle (Psylliodes punctulata)1 occurs throughout the northern U.S. and southern Canada. It also can be found on a wide range of plants, including cabbage, cucumber, hops, cannabis, strawberry, tomato, and beet. Adults feed on the underside of leaves. Hop flea beetle is one of the first flea beetles to appear in spring, and larvae feed on root hairs of the host plants. A single generation is produced with new-generation adults emerging in August. After a brief period of feeding, the adults move to overwintering sites among sheltering debris. 1

Coleoptera: Chrysomelidae (Alticinae)

194

A

B A. Potato flea beetles and damage to potato. DAVID SHETLAR

B. Potato flea beetle

damage to leaves and fruit of tomato. WHITNEY CRANSHAW

C. Corn flea beetle. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Corn flea beetle damage. JIM KALISCH, UNIVERSITY OF NEBRASKA

C D E

E. A Chaetocnema species

F

of flea beetle. TOM MURRAY

F. Palestriped flea beetles. WHITNEY CRANSHAW

G. Redheaded flea beetle. DAVID SHETLAR

H. Hop flea beetle. TOM MURRAY

G H

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF-FEEDING WEEVILS Weevils are the largest family of insects and have a wide range of feeding habits. The chewing mouthparts of the adults tip an elongate “snout” that can allow some species to chew into stems, seeds and developing fruit. Adults that feed on leaves typically confine feeding along the leaf edge, producing angular notching wounds. Few species of weevil larvae feed on leaves, the great majority instead developing within seeds or fruit. (These are discussed in chapters 4 and 7). Others, notably the bark beetles, develop as borers in stems or trunks, and a few occur in roots. (These are discussed in chapters 5 and 6.) Adults of weevils that chew along the edges of leaves are usually active at night and rarely observed. Often the most common species involved in such injuries are various root weevils of the genus Otiorhynchus, many of which are widespread in North America. Adults of the black vine weevil (O. sulcatus)1 chew on foliage of hemlock, yew, rhododendron, euonymus, other broadleaf evergreens, and many perennials. The strawberry root weevil (O. ovatus), rough strawberry root weevil (O. rugosostriatus), and claycolored weevil (O. singularis) also chew notches in the leaves of a variety of landscape plants and small fruits. Lilac root weevil (O. meridionalis) feeds on leaves of lilac, privet, and peony, among other plants. Cribate root weevil (O. cribricollis) is a pest of olive, grape, citrus, and various fruit trees in California. These species are often more damaging as larvae, which develop on roots and are further discussed in chapter 6. Nemocestes incomptus,1 known variously as the “woods weevil” and “raspberry bud weevil,” is a common member of the root weevil complex associated with landscape plants in Washington and British Columbia. Most adults begin to emerge in late summer and may feed throughout the winter months as temperatures allow. Distinct generations do not occur, and all life stages may be present throughout the year. Adults are sooty dark brown, covered with small hairs, and about ⅓ inch long. Another native forest species in the region is Dyslobus granicollis,1 which occasionally damages landscape plantings and strawberries. Like most root weevils, adults are flightless, so damage usually occurs only in limited sites adjacent to woodlands. Dyslobus decoratus, sometimes known as the “decorated strawberry root weevil,” is another leaf-notching species, native to the Pacific Northwest, which has expanded its range into the Rocky Mountain States, apparently through human-assisted movement of plant material. Buckthorn is a particularly favored plant. Adults of the obscure root weevil (Sciopithes obscures)1 chew notches on the leaf margins of rhododendron. This insect is also more damaging in the larval stage and an important nursery pest in the Pacific Northwest and northern California. At least three European Polydrusus species1 have become established in North America. Polydrusus impressifrons is a pale green weevil that chews buds and notches leaves of many deciduous trees and shrubs in late spring. It occurs in many areas of the northern U.S. and southern Canada and is most often associated with birch, black locust, blueberry, pear, plum, poplar, rose, strawberry and willow. P. formosus, known as the green immigrant weevil, is brightly colored green and also feeds on leaves and open blossoms of many woodland trees and shrubs and some fruit trees. It has also been steadily extending its range and can be found in many of the northern forested areas. More recently introduced, with present range limited to northeastern areas, is P. cervinus. This weevil is predominantly brown colored, but greenish scales may be present.

196

A

B

C

D

E

F

G H

I

A. Black vine weevil on Taxus. DAVID SHETLAR

B. Black vine weevil notching

J

of euonymus.

G. Leaf notching characteristic

of lilac root weevil. WHITNEY CRANSHAW

H. A Nemocestes species of root weevil.

WHITNEY CRANSHAW

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Strawberry root weevil

I. Obscure root weevil.

DAVID SHETLAR

J. Leaf injury produced by

and leaf injury.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Rough strawberry root weevil. WHITNEY CRANSHAW

E. Clay-colored root weevil. TOM MURRAY

WHITNEY CRANSHAW

K. Dyslobus decoratus. WHITNEY CRANSHAW

L. Polydrusus formosus, the

“green immigrant weevil.”

F. Lilac root weevil. WHITNEY CRANSHAW

K

Dyslobus decoratus.

DAVID SHETLAR

L

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF-FEEDING WEEVILS Myllocerus undecimpustulatus undata,1 sometimes known as the “Sri Lanka weevil,” was first detected in southern Florida in 2000 and has since spread to include most of the state. Adults notch the leaves of a great number of plants, including fruit trees (e.g., citrus, lychee, peach) various ornamentals (e.g., crape myrtle, green buttonwood, cocoplum, pygmy date palm, eucalyptus) and some vegetables (e.g., pepper, eggplant, sweetpotato). Larvae have been observed to feed on the roots of several herbaceous plants. Twobanded Japanese weevil (Callirhopalus bifasciatus)1 can cause extensive defoliation of many deciduous shrubs in the northeastern quadrant of the U.S. Adult feeding is typical of that of many other weevils, producing notched cuts that extend in from the leaf margin. Privet, azalea, forsythia, dogwood, holly, spirea, and ash are among the plants injured by adults. Larvae have been observed feeding on roots of forsythia and privet. One generation is produced annually, but all stages may be present throughout the year. Adults are about ¼ inch and light brown with two darker bands across the back. Fuller rose beetle (Naupactus cervinus)1 is the most widely distributed of the four species of introduced “whitefinged weevils” (Naupactus spp.). Larvae girdle roots, but the most conspicuous damage is caused by adults, which make notching wounds on foliage and consume buds and blossoms. Unsightly dark fecal matter is left around feeding sites. Fuller rose beetle is flightless, and only females occur. Overwintered weevils crawl to nearby plants in spring and feed on leaves. Eggs are laid in small, sticky masses, usually in soil but also in bark crevices or between leaves. Larvae enter the soil and chew on roots. Pupation occurs near the soil surface. There are one to two generations per year. Ithycerus noveboracensis,2 sometimes referred to as the “New York weevil,” occurs in wooded areas of the northeastern U.S. and southern Canada. Adults chew on the new growth, leaf petioles, and buds of many different trees but are most noticed on white oak and American beech. Eggs are laid in the soil and larvae feed on the roots of the same host plants. Asiatic oak weevil (Cyrtepistomus castaneus)1 feeds on leaves of many woody plants, including oak, beech, red maple, dogwood, willow, sycamore, redbud, persimmon, and viburnum. It has been particularly damaging to chestnuts. Its present range extends to Missouri from its original point of introduction in New Jersey. When abundant it may be a significant nuisance invader of homes. Hairy spider weevil (Barypeithes pellucidus),1 also known as “juniper root weevil” and “hairy broadnosed weevil,” is very similar in size and shape to the strawberry root weevils, but brown with thick hairs Hairy spider weevil in strawberry. scattered over the entire body. This is a native of Europe, but it is now ROBIN ROSETTA, OREGON STATE UNIVERSITY generally spread across northern North America. The adults feed primarily on the leaf buds and foliage of various landscape and garden plants. It is assumed that the larvae feed on plant roots, but they have not been reported to produce significant damage; this insect attracts attention primarily when it wanders into buildings. Another small weevil of European origin that has the habit of incidentally entering buildings is Trachyphloeus asperatus. Life history of this species, including host plants, is very poorly known. Adults of the pea leaf weevil (Sitona lineatus)1 chew notches along the edges of leaves at night. Various legumes are hosts, but it is most often observed on garden peas and fava beans. Larvae develop on roots of perennial legumes such as clover and alfalfa. Pea leaf weevil presently occurs in parts of the Pacific Northwest and extends into the Prairie Provinces. 198

A

C F

B

D G

E A. Damage to lychee by

Myllocerus undecimpustulatus undata, the “Sri Lanka weevil.” DOUG CALDWELL, UNIVERSITY OF FLORIDA

B. Mating pair of

“Sri Lanka weevil.” DOUG CALDWELL, UNIVERSITY OF FLORIDA

C. Twobanded Japanese

weevil.

DAVID SHETLAR

H

D. Fuller rose weevil. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

E. A Naupactus species

I

of whitefringed weevil feeding on blueberry.

JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

F. Asiatic oak weevil and damage. DAVID SHETLAR

G. Trachyphloeus asperatus. TOM MURRAY

H. Hairy spider weevil. ROBIN ROSETTA, OREGON STATE UNIVERSITY

I. Pea leaf weevil notching pea leaf. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAF-FEEDING WEEVILS Vegetable weevil (Listroderes costirostris)1 also damages carrot as well as turnip, potato, and other root crops in the Gulf States. It is also reported as a pest of dichondra lawns in California. Adults feed on foliage and buds. Feeding injury by larvae can occur on roots but is often aboveground, concentrated around the soil surface, but also involving buds and foliage. Feeding activity of both adults and larvae occurs primarily at night. Vegetable weevil has only one generation a year, with peak adult activity and egg-laying occurring in late summer and early fall. Clover, particularly red clover, is host to two leaf-feeding weevils. Larvae of the clover leaf weevil (Hypera zoilus)1 mature in spring, when they feed on the buds and emerging leaves, producing ragged foliage. Adults emerge late May through July but do not lay eggs until autumn. Young larvae are the primary overwintering stage. The lesser clover leaf weevil (Hypera nigrirostris) overwinters as adults. Peak feeding by this species is from late May through July. Larvae of a related species, the alfalfa weevil (Hypera postica), chew the leaves of alfalfa early in the season; this is the most important insect pest of the alfalfa in North America. An unusual group of weevils associated with foliage are the flea weevils. These are small weevils with enlarged hind legs that allow them to jump in a manner similar to flea beetles (page 190). Most are in the genus Orchestes1 and the larvae of these develop as leafminers, producing small blotch mines in leaves of their host plant (page 218). Adults produce shothole wounds in leaves, similar to flea beetles. Apple flea weevil (Orchestes pallicornis)1 is an occasional pest of apple but may also attack wild cherry and hornbeam. The adults produce shotholes in leaves, both before and after larval development. Adults lay eggs in the midvein of host leaves and the larvae mine to the leaf margin to make a small blotch mine. These mines are often mistaken for late frost damage or disease. European elm flea weevil (O. alni) can be locally common on elm, particularly Siberian elm. Overwintered adults move to emerging leaves in spring and chew small holes in leaves, which produce shothole wounds. The Alfalfa weevil larva and damage. WHITNEY CRANSHAW subsequent larval generation makes leaf mines, but adults then emerge in early summer and feed heavily on leaves at this time, often producing extensive shothole wounding. Another common species is the alder flea weevil (O. testaceus). Another group of weevils of odd habit are the leafrolling weevils.3 Adults tightly roll the tips of leaves in a process of strategic leaf cuts, laying an egg in the center. A specific name is given to the leaf roll “nest” they produce, a nidus, and the process of making a single nidus (nidification) takes about two hours to complete. Homeolababus analis is a common species in the southern states, using various oaks as host plants. Synobabus bipustulatus is more widely distributed in eastern North America and develops on oak, walnut, pecan, and hornbeam. The three other North American species are primarily associated with oaks. 1

Coleoptera: Curculionidae; 2 Coleoptera: Brentidae;

3

Attelabidae (Attelabinae)

200

A B

C D

E

A. Vegetable weevil.

F

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

B Vegetable weevil larva. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Clover leaf weevil larva. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Clover leaf weevil. WHITNEY CRANSHAW

G

E. Lesser clover leaf weevil. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Shothole injuries produced by European elm flea weevil. WHITNEY CRANSHAW

H

G. European elm flea

weevils on new growth of elm. WHITNEY CRANSHAW

H. Leaf rolled nest cells

of a leafrolling weevil. DAVID SHETLAR

I. Leafrolling weevils

making leafroll nest cell. DAVID SHETLAR

J. Leafrolling weevil

making cuts prior to leafroll. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

I

J

K. The leafrolling weevil

Synobabus bipustulatus. DAVID CAPPAERT, BUGWOOD.ORG

K

INSECTS THAT CHEW ON LEAVES AND NEEDLES

JAPANESE BEETLE (Popillia japonica)1 hosts Adults feed on foliage of more than 300 species, including rose, mountain-ash, willow, linden, elm, grape, Virginia creeper, bean, Japanese and Norway maples, birch, pin oak, horse chestnut, rose of Sharon, sycamore, ornamental apple, plum, and cherry. Larvae develop on roots of various grasses. Damage Japanese beetle is one of the few beetles that is highly damaging in both the adult and larval stages. Adults feed on foliage and flower petals, producing skeletonizing injuries that cause leaves to appear lacelike. In high populations they may completely consume flower petals and more tender foliage. The larva, a type of white grub that feeds on grass roots (page 468), is among the most damaging pests of turfgrass in the northeastern quadrant of the U.S. Distribution Originally introduced into New Jersey and now important in the northeastern U.S. and parts of southern Canada. This species ranges into Colorado to the west, Arkansas to the south, and is found in parts of northern Alabama, northern Georgia, and South Carolina. Its range continues to expand, with localized infestations present in many other states. Appearance Adults are generally metallic green with bronze wing covers. A row of white hair brushes is present along each side. The overall form is broadly oval, and length ranges from about ⅓ to nearly ½ inch. Larvae are typical white grubs, C-shaped when at rest and a translucent creamy white, and feed on organic matter in the soil or under turf. Life History and Habits Winter is spent in soil as a nearly full-grown grub that moves deeper into the soil for winter. As soils warm, the grubs resume feeding on grass roots and pupate 2–4 inches below the surface, in a tamped earthen cell. Adults emerge in late June and early summer, feed on foliage, and mate, returning to lawn near sunset. The aggregation pheromones these insects produce combined with attractive odors produced by their food plants often result in large numbers feeding together. Females lay eggs in small masses in soil cavities they excavate 2–4 inches deep. Most eggs are usually laid by early August, but some are laid into September. Over most of its range Japanese beetle has a 1-year life cycle, although it may extend to 2 years in the extreme northern areas where it occurs.

Other Leaf-feeding Scarabs Some other scarab beetles feed on foliage, although feeding damage is much less conspicuous than that by the Japanese beetle. Various species of May/June beetles (Phyllophaga spp.)1 occur east of the Rocky Mountains; adults feed on foliage during the night. Often certain broadleaf trees are preferred, with oaks and maples being especially attractive. A few chew needles of pines. The lined June beetles (Polyphylla spp.) tend to be more western in distribution and similarly feed on leaves at night. Both develop as white grubs that feed on roots (page 464), but adults sometimes emerge en masse, accumulating by the hundreds in landscape trees at night to mate and feed. By morning, they return to the soil and the trees appear mysteriously defoliated. If these beetles are suspected, going out at night with a flashlight will soon disclose their activities. Other scarab beetles that may cause limited damage to foliage include the rose chafer (Macrodactylus subspinosus)1 and spotted pelidnota (Pelidnota punctata).1 1

Coleoptera: Scarabaeidae

202

A C

D

E

B

A. Japanese beetles and skeletonizing leaf injury. DAVID SHETLAR

F H

I

G

B. Japanese beetle injury

to Virginia creeper. WHITNEY CRANSHAW

C. Japanese beetle

injury to rose.

WHITNEY CRANSHAW

D. Life stages of

Japanese beetle. DAVID SHETLAR

E. Japanese beetles

flying to trap.

WHITNEY CRANSHAW

F. Japanese beetle mating ball on lawn. DAVID SHETLAR

J

G. Damage to pinyon

K

by the June beetle Phyllophaga falsa. WHITNEY CRANSHAW

H. June beetle feeding

on oak at night. DAVID SHETLAR

I. Tenlined June beetle,

Polyphylla decemlineata. WHITNEY CRANSHAW

J. Spotted pelidnota. DAVID SHETLAR

K. Rose chafer. DAVID SHETLAR

INSECTS THAT CHEW ON LEAVES AND NEEDLES

MEXICAN BEAN BEETLE (Epilachna varivestis)1 hosts Garden beans and field beans primarily; soybean and cowpea are less commonly damaged. Damage Mexican bean beetle is a plant-feeding lady beetle. Larvae feed on the underside of bean leaves in a typical skeletonizing manner, producing a lacy appearance. Adults primarily chew leaves but may also feed on green pods. Distribution Originally restricted to the southeastern U.S. and Mexico but has greatly extended its range and is now common in most areas east of the Rockies. It tends to be more abundant and damaging in southern areas of this range. Appearance Adults are a typical oval form, similar to that of other lady beetles, and slightly larger than most. General color ranges from nearly mustard yellow to copper, with those present late in the season often reddish brown. Each wing cover is marked with eight dark spots, arranged in three rows (3-3-2). Larvae are yellow or orange-yellow and quite spiny. Life History and Habits Mexican bean beetles winter in the adult stage in protected areas along the edges of plantings and emerge over an extended period in late spring. Females lay masses of yellow eggs on the lower leaf surface. The larvae feed for about 3 weeks, skeletonizing the lower surface of the leaf. When full grown they pupate underneath a leaf, often in small groups. One generation is typical in the western and northern states, but up to three may occur in the southeast. Greatest feeding and injury typically occur in late July and August.

Other Leaf-feeding Lady Beetles A few other lady beetles also develop by feeding on plants. Squash beetle (Epilachna borealis)1 is a minor pest of squash family plants and found in the eastern U.S., particularly in the Atlantic States. Adults and larvae chew foliage in a manner similar to that of the Mexican bean beetle but are rarely seriously damaging. Two generations occur annually in southern areas, one in the north. The 24-spot lady beetle (Subcoccinella vigintiquatuorpunctata) is a European species that is now present over a large area of the eastern U.S. Larvae rarely damage garden plants, but they have a wide host range that includes campion, dianthus, and many legumes.  Coleoptera: Coccinellidae

1

204

A

B

A. Mexican bean beetle.

E. Mexican bean beetle pupae.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

B. Mexican bean beetle adult recently emerged from pupa.

F. Mexican bean beetle larvae and damage.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

C. Mexican bean beetle egg mass.

G. Squash beetle.

WHITNEY CRANSHAW

CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

D. Mexican bean beetle damage. WHITNEY CRANSHAW

H. 24-spot lady beetle. TOM MURRAY

C

D

E

F

G

H

INSECTS THAT CHEW ON LEAVES AND NEEDLES

BLISTER BEETLES Blister beetles (Meloidae) are elongated beetles of moderate size. They have relatively soft wing covers that do not cover the tip of the abdomen. More than 300 species occur in North America, but few are commonly associated with gardens. The common name of the family is related to production of a defensive compound in their blood, cantharidin, which can be highly irritating and capable of producing blisters in high concentration. Fortunately, most blister beetles found in gardens contain relatively low amounts of cantharidin and pose little threat to gardeners who may come in contact with them. Only the adult blister beetles feed on plants. Larvae develop as predators of other insects. Most (all Epicauta species) feed on eggs of grasshoppers. Others (Lytta spp., Meloe spp., Nemognatha spp.) develop as parasites of ground-nesting bees. Epicauta is an extremely large genus, with more than 150 North American species. All develop as predators on grasshopper egg pods. Adults of many feed on pollen, but some chew flowers and leaves. Striped blister beetle (Epicauta vittata)1 feeds on leaves of a wide range of garden and landscape plants such as Amaranthus, bean, beet, carrot, cabbage, corn, eggplant, melon, mustard, pea, pepper, potato, radish, spinach, squash, sweetpotato, and tomato. Adults will also chew on developing fruit of peas, peppers, and tomatoes. Adults of ashgray blister beetle (E. fabricii) and margined blister beetle (E. funebris) feed primarily on flower petals. but they will also feed on leaves, producing a very ragged appearance to plants. The black blister beetle (E. pennsylvanica) seems primarily a pollen-feeding species but it will also feed some on flowers. The clematis blister beetle (E. cinerea) looks like a small version of the margined or gray blister beetle and the adults feed on the leaves of clematis, sometimes causing extensive defoliation. These species are generally distributed across the Prairie States eastward. Western species of Epicauta include the spotted blister beetle (E. maculata), caragana blister beetle (E. subglabra), and E. ferruginea. Blister beetles in the genus Lytta are often quite brightly colored with bright orange and yellow colors or a metallic blue or green sheen, and antennae consisting of a row of beads. The larval habits of this genus differ from those of Epicauta spp. in that the larvae develop as parasites within the nests of ground-nesting solitary bees (rather than in egg pods of grasshoppers). Nuttall blister beetle (L. nuttalli) feeds on lupines, other legumes, and occasionally canola in the western states. Adults are brilliant iridesent blue-green, often with violet coloration of the wings. Say blister beetle (L. sayi) is a metallic green with bright yellow-orange legs that is common over eastern North America. The adults are found on flowers of willow, rose, locusts, lupines, and wild cherry in late spring. The oil beetles (Meloe spp.) are very large, black blister beetles. They have a distended abdomen that is only partially covered by the wing covers and are incapable of flight. Adults chew leaves and flowers of plants and on occasion some species have been reported to damage potatoes, turnips, Ranunculus, and some other garden plants. Adults of the most commonly observed species (e.g., M. laevis, M. niger, M. impressus) are usually active in late summer and autumn. Larvae of the oil beetles develop as parasites of ground-nesting bees. Adults lay masses of eggs in soil cavities and the active first-stage larvae (triungulins) climb to flowers upon emergence, where they wait to attach to visiting bees. If transported by a bee back to its the nest, the oil beetle larvae will then consume the food provided for the larval bees and usually eat the developing bee larvae.  Coleoptera: Meloidae

1

206

A B

C D

A. Striped blister beetle.

E

CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

B. Ashgray blister beetle. WHITNEY CRANSHAW

C. Margined blister

beetle.

DAVID SHETLAR

D. Black blister beetle. DAVID SHETLAR

E. Clematis blister beetle. TOM MURRAY

F

F. An oil beetle, Meloe

species.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G. Spotted blister beetle. JOHN CAPINERA, UNIVERSITY OF FLORIDA

H. Nuttall’s blister beetle. WHITNEY CRANSHAW

G H

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SLUGS AND SNAILS Slugs and snails are types of animals known as gastropods, fairly close relatives of clams, mussels, and other mollusks. As such, they have several features that differ from those of the arthropods (insects, mites, spiders, crabs, and the like), such as lack of distinct segmentation and an external skeleton (when present) that grows with the mollusk rather than being shed on a periodic basis. The body is soft and moves by means of a broad, muscular “foot” (sole) that covers the underside. On slugs, a large lobe called the mantle is present on the front half of the back; this is covered by a hard shell in snails. Two pairs of tentacles are present in the front, a short pair for sensing odors and a longer pair tipped with eyes. Many slugs and snails are hermaphrodites, possessing both sex organs. In some species, being male or female can occur at different times, causing the slug to pass through male and female phases. Other slugs may be permanently hermaphroditic, as are most land snails. Slugs and snails typically feed at night or during heavily overcast periods, avoiding sunny, drying conditions. During the day most slugs and snails migrate to sheltered areas, such as under debris, in soil cracks, or within shaded areas of dense vegetation.

Gray Garden Slug (Deroceras reticulatum)1 hosts Almost all garden plants, although lettuce, bean, corn, and hosta are among those particularly favored. The gray garden slug is particularly damaging to seedlings. Damage Slugs feed by using a rasplike structure called a radula that scrapes away plant tissues. They typically produce irregular damaged areas on foliage and leave slime trails on areas where they have been active. Distribution Of European origin, the gray garden slug is now widely present through North America but most common in the northern states and Canada. Appearance Adults are moderate size, ranging from 1 to 1½ inches long. Color varies from cream to gray or pinkish gray, with some dark flecks. The mantle area is large, covering a third of the body or more, and on close inspection has concentric folds. The mucous slime is normally clear but will turn milky if the slug is disturbed, leading to another common name, “milky garden slug.” Life History and Habits Gray garden slug is quite tolerant of low temperatures and may be active at fairly cool temperatures. Most activity occurs during spring and fall, with masses of clear eggs laid in soil cracks. Development may be suspended during very warm temperatures. The slugs develop rapidly, becoming full grown in 3–6 months. Life span rarely exceeds one year.

Other Garden Slugs Marsh slug (Deroceras laeve)1 is a relatively small slug, about ¾–1 inch long. Color ranges from dark brown or yellowish to nearly black but the slug may be distinguishable by tentacles that are smoky blue-black. It is one of the very few slugs commonly encountered that are native to North America and occurs in fairly moist sites, including many gardens. The marsh slug can reproduce year-round where temperatures allow and can often be the earliest active slug in gardens in spring.

208

A

B

C

E

F

D

A. Slug with slime trail. WHITNEY CRANSHAW

B. Gray garden slugs. WHITNEY CRANSHAW

C. Brown garden snail. BOB HAMMON, COLORADO STATE UNIVERSITY

D. Marsh slug. LYLE BUSS, UNIVERSITY OF FLORIDA

E. Gray garden slug and associated leaf injury. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Slug damage to hosta. DAVID SHETLAR

G. Slug eggs under garden timber. DAVID SHETLAR

G

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SLUGS AND SNAILS Ten Arion species2 of slugs, all native to Europe, have become established in areas of the northern U.S. and southern Canada. Most are omnivores that feed on a variety of materials, including living and dead plant material, fungi, animal feces, and carrion; many can be seriously damaging to ornamental and vegetable plants. Two of the larger species are Arion rufus (European red slug or chocolate arion) and A. ater (black arion), which may reach 3–6 inches when full grown. Both show a considerable range of colors, from dark brown or black to orange or reddish, and they have been known to interbreed. A. subfuscus (dusky slug) is a slightly smaller species, ranging up to 3 inches when full grown, and variably gray-brown to orange brown. It has established over a broad area of the U.S., including some southern states, and in some sites appears particularly well adapted, displacing other slug species. Other species known to range at least as far south as Kentucky include A. hortensis (black field slug, yellow-soled slug, southern garden slug), A. circum­ scriptus (brownbanded arion), and A. fasciatus (orangebanded arion). These are gray-colored slugs with the underside (“sole”) light-colored yellow or white. Arion slugs have a 1-year life cycle. The tawny garden slug (Limacus flavus)3 is a moderately large species, ranging 3–4½ inches, with yellowish coloration and gray-green mottling. Of approximately similar size is the threebanded slug (Lehmannia valentiana),3 a somewhat translucent slug, of yellow-gray or yellow-violet color, and often having two darker bands on the back. It feeds primarily on decaying plant matter and fungi but can be a pest of living plants in very moist sites, including greenhouses. Considerably larger is Limax maximus,3 known as the spotted leopard slug or giant garden slug, which can range to 6 inches long. It is generally gray but often has conspicuous dark spotting. Limax maximus feeds primarily on decaying plant matter, animal feces, and fungi and prefers shaded areas, and only infrequently damages garden plants. It is a long-lived species that may live 3–4 years. Most slugs tend to confine feeding damage to aboveground parts of plants, but the greenhouse slug (Milax gagates)4 burrows more extensively and may damage belowground parts of plants, including roots and tubers. It ranges up to about 2½ inches and is gray-brown to black, with a ridge (keel) running along the back. The greenhouse slug is well established and often very damaging in many areas in the Pacific States and Hawaii and has been introduced into some areas of the eastern U.S. Greenhouse slugs can also develop more rapidly than most other slugs, completing a generation within 6 months. Florida leatherleaf (Leidyula floridana)5 is a mottled brown slug, more flattened in cross section than other slugs, and has a very narrow sole. It is a moderately important garden pest species in Florida and has more recently been introduced into areas of Louisiana and Texas. 1, 2, 3, 4, 5

Class Gastropoda. With very few exceptions (e.g., Veroncellidae),

all terrestrial slugs and snails are in the clade Stylommatophora. 1

Agriolimacidae; 2 Arionidae; 3 Limacidae; 4 Milacidae; 5 Veronicellidae

A. European red slug. GARY BERNON, USDA APHIS, BUGWOOD.ORG

B. European red slug. GARY BERNON, USDA APHIS, BUGWOOD.ORG

C, Dusky slug. GARY BERNON, USDA APHIS, BUGWOOD.ORG

D. Yellow-soled slug. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Tawny garden slug. DAVID CAPPAERT, BUGWOOD.ORG

F. Tawny garden slug. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

G. Spotted garden slug. JIM KALISCH, BUGWOOD.ORG

210

A C

B

D E

F

G

INSECTS THAT CHEW ON LEAVES AND NEEDLES

SLUGS AND SNAILS

Brown Garden Snail (Cornu aspersum)6 hosts Brown garden snail feeds on a wide range of commonly grown vegetables, flowers, shrubs, and fruit trees. Boxwood, rose, hibiscus, lettuce, peach, magnolia, and citrus are among the plants most commonly damaged. Dead plant matter is also commonly consumed. The brown garden snail is also one of the escargot species that is cultured for human consumption. It is sometimes referred to as the “petit gris” and said to taste best in spring when levels of calcium salts are lowest. Damage Brown garden snail feeds primarily on leaves but may rasp the bark of twigs and small branches. Distribution Purposefully introduced as a potentially edible species in the San Francisco area in the 1850s and currently common throughout the Pacific States. It is found in localized infestations elsewhere, particularly in the southern U.S., although it has been eradicated from Florida. Appearance The globular brown shell is slightly wrinkled and often flecked with yellow. Full grown, the shell may be 1½ inches in diameter with four or five whorls. Life History and Habits Brown garden snail remains dormant in winter, sealing itself in the shell with a thin membrane (epiphragm). Activity resumes in spring, and adults lay masses of eggs, up to six dozen at a time, in soil. Eggs hatch in a few weeks, and the snails grow slowly, becoming full grown in one to two years. This species can be long lived, living up to five years.

Other Garden Snails The Cuban brown snail (Zachrysia provisoria)7 is a species introduced into parts of Florida that is approximately similar in size and shape to the brown garden snail. It is reportedly very damaging to many ornamental plants. The Asian tramp snail (Bradybaena similaris)8 is a smaller species, now established in much of the southeastern U.S., reported to feed on cucurbits, legumes, hibiscus, and several ornamental plants. The white garden snail (Theba pisana)6 occurs in coastal areas of California. It is particularly well adapted to dry sites, burrowing deeply into soil when laying eggs. During dormant periods it may be seen conspicuously attached to fences, walls, and tree trunks. Glass snails (Oxychilus spp.)9 are rather small snails, with a shell about ½ inch in diameter. The shell is translucent, pale brown, and depressed, so that it is only about 1⁄6 inch wide, allowing the snails to move under logs and rocks, where they sometime aggregate in large numbers. These snails feed on living and dead plant matter but rarely cause noticeable injury. The body of the garlic glass-snail (Oxychilus alliarus) is bluish and it can emit a garlicky odor when disturbed. The cellar glass-snail (Oxychilus cellarius) has a gray body. These snails feed on a wide variety of materials, including both living and dead plant matter as well as soft-bodied animals such as small slugs, snails, and earthworms. They can be found year-round, with peak breeding in autumn. A few snails are primarily predatory, feeding on soft-bodied invertebrates (slugs, snails, earthworms). The rosy predator snail (Euglandina rosae)10 is a predatory snail native to the southeastern U.S. The decollate snail (Rumina decollata)11 is a Mediterranean species that has been introduced into North America and subsequently spread, often purposefully, so now it can be found broadly across the southern U.S. 6, 7, 8, 9, 10, 11 6

Class Gastropoda, All terrestrial snails are in the clade Stylommatophora.

Helicidae; 7 Pleurodontidae; 8 Bradybaenidae; 9 Zonitidae; 10 Spiraxidae; 11 Subulinidae

212

A. Brown garden snail. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Brown garden snail at egg hatch. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. White garden snail. DAVID ROSEN, COURTESY UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

D. Brown garden snail laying eggs. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Glass snail. WHITNEY CRANSHAW

A B

C

D

E

F

F. Shells of glass snails. JIM KALISCH, UNIVERSITY OF NEBRASKA

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAFMINERS AND NEEDLEMINERS Some of the most discriminating feeders among the insects are the leafminers and needleminers. These insects tunnel between the upper and lower leaf surfaces, feeding on the soft inner tissue and avoiding the tough epidermis. Immature stages of many different groups of insects share the leafmining habit, including the larvae of various flies, small moths, beetles, and sawflies. They are often classified by the pattern of the mine they create. Serpentine leaf mines meander across the leaf, gradually increasing in width as the insect grows. More common are various blotch leaf mines, which are an irregular but generally round form. One subgroup of these are the tentiform leaf mines, blotchlike mines produced by some types of moth larvae that tie the interior mine with silk in a manner that causes it to pucker (like a tent) as it dries. Many of the fly leafminers in the family Agromyzidae make a serpentine mine as first-instar maggots, but they dramatically enlarge the mine into a blotch when in the second and third instars. These mines are often called comma leaf mines. In addition, small pinholes are usually present that result from feeding wounds by adult female agromyzid flies. These are produced when the female uses her ovipositor to mash underlying cells to release plant juices on which she will feed. As leaves expand, the pinhole wounds can expand into larger shotholes.

Vegetable Leafminer (Liriomyza sativae)1 hosts Many vegetables, including bean, tomato, potato, onion, pepper, squash, and melon. Damage Larvae make thin, meandering serpentine mines. Puncture wounds (pinholes) are made by the ovipositor of the female during egg-laying or to produce fluid for feeding, and these may give the leaves a stippled appearance. Serious problems are often associated with insecticide use that adversely affects the many natural enemies that attack this insect. Distribution Predominantly a problem in warmer areas of the southern U.S. but occasionally ranges northward into the Midwest. Appearance Adults are small (ca. 1⁄15 inch) yellow and black flies. Larvae are pale, slightly greenish maggots found within serpentine-type leaf mines. Life History and Habits Eggs are inserted into foliage, producing small puncture wounds. Larvae develop rapidly under warm temperatures and may complete development in under 2 weeks. Often they then cut the leaf surface, drop to the soil, and pupate; pupation occasionally occurs in the mined leaf. Numerous overlapping generations occur during the year.

Related Species American serpentine leafminer (Liriomyza trifolii),1 also known as chrysanthemum leafminer, is closely related to vegetable leafminer and can cause many similar injuries. It also has a wide range of hosts but is particularly damaging to flower crops, notably chrysanthemum. Primarily limited to warmer climates, it has spread widely among greenhouse crops. Problems are particularly severe following certain pesticideuse practices that devastate natural enemies. A species of similar habit is pea leafminer (L. huidobrensis). Widely distributed in South and Central America, it is found in areas of the western U.S. Serpentine leafminer (L. brassicae) is also primarily a tropical species but may be common in the southern U.S. Cabbage, broccoli, mustard, and nasturtium are among the reported hosts. 214

A. Serpentine mines produced by vegetable leafminer on bean leaves. WHITNEY CRANSHAW

B. Extreme leafminer

damage to melon leaves. DAVID RILEY, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

C. Adult serpentine leafminer,

close-up.

DAVID SHETLAR

A

D. Adult vegetable leafminer on

B

onion leaf showing relative size. WHITNEY CRANSHAW

C D

E. Vegetable leafminer larva

outlined with leaf mine in onion. WHITNEY CRANSHAW

F. Pupa of a Liriomyza sp. leafminer. DAVID SHETLAR

G. Leafmines produced by the

columbine leafminer Phytomyza aquilegivora. JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Adult columbine leafminer. DAVID SHETLAR

E

F

G H

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAFMINERS AND NEEDLEMINERS, AND LEAFMINING WEEVILS

Other Serpentine-type Leafmining Flies and Caterpillars The columbine leafminer (Phytomyza aquilegivora)1 produces serpentine mines in leaves of columbine. Winter is spent in the pupal stage at the base of previously infested plants, and adults emerge in early spring. Females insert eggs into the foliage but also use their ovipositor to make pinhole wounds that provide plant fluids on which they feed. These oviposition injuries appear as small white spots on leaves. The larvae develop within the mines, which gradually widen as the larvae grow. Pupation also occurs in the mines. As many as five generations may be produced per season. Other Phytomyza spp. leafminers make blotch-type mines in columbine and are discussed below. Daylily leafminer (Ophiomyia kwanosis)1 is a newly established insect in North America that has spread widely across the eastern and southern states in the past decade. Adults typically insert eggs into the upper leaf tissues of daylilies, and larvae create serpentine mines. Pupation occurs within the mines and multiple generations are produced annually. Aspen leafminer (Phyllocnistis populiella)2 caterpillars make meandering mines just under the upper leaf surface of aspen and other Populus species. The mines are distinctively silvery with a dark line of excrement in the center. Phyllocnistis vitifoliella produces serpentine mines just under the surface of grape and Virginia creeper. In southern California, citrus leafminer (P. citrella) makes meandering tunnels in the leaves of citrus. Pecan serpentine leafminer (Stigmella juglandifoliella)3 caterpillars produce serpentine mines between the leaf veins on the upper surface of pecan and black walnut. A large number of other Stigmella species also occur, producing serpentine mines in leaves of various roses, caneberries, birch, sumac, oak, elm and many other plants.

EUROPEAN ELM FLEA WEEVIL

(Orchestes alni)4

hosts Elm, particularly Asian species Damage Adult feeding produces small shothole wounds in the leaf interior, resulting in a lacey appearance when injury is extensive. Larvae develop as leafminers that create a serpentine mine originating from a main leaf vein and terminating in a blotch leaf mine at the edge of the leaf. Distribution Broadly distributed across the midwestern and Rocky Mountain states. Appearance Larvae are cream-colored grubs that develop in leaf mines. The mines typically originate near the midrib and produce a serpentine course before terminating in a large blotch mine at the edge of the leaf. The adults are small (⅛ inch) reddish-brown beetles with black spots. They have a short snout on the head and their hind legs are enlarged to allow them to jump. Life History and Habits Winter is spent in the adult stage, in the vicinity of previously infested elm trees. Adults resume activity in early spring and females lay eggs in larger veins of new leaves. Upon egg hatch, the larvae tunnel through the leaf as they feed, producing a serpentine mine that gradually enlarges in diameter as the insect gets older. The mines terminate at the leaf edge where the larvae remain and produce a blotchy area of mined tissue. Pupation occurs in the mine and adults emerge in late May and June. Adults feed mainly on the underside of leaves, producing shothole injuries to the leaf interior. Where abundant, the insects will make foliage of affected trees appear lacy. Adults are present through early August then move to sheltering cover for winter. One generation is produced annually. 1

Diptera: Agromyzidae; 2 Lepidoptera: Gracillariidae; 3 Lepidoptera: Nepticulidae; 4 Coleoptera: Curculionidae

216

A

B

C

D

E

F

G

A. Daylily leafminer larva in tunnel. GARY STECK, FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES

B. Daylily leafminer adult. GARY STECK, FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES

C. Leafmine produced by

E. Serpentine leafmine produced

by Phyllocnistis vitifoliella. WHITNEY CRANSHAW

F. Leaf injury produced by

citrus leafminer. WHITNEY CRANSHAW

the aspen leafminer.

G. Leaf injuries produced by

WILLIAM CIESLA, FOREST HEALTH MANAGEMENT INTERNATIONAL, BUGWOOD.ORG

JERRY A PAYNE, USDA-ARS, BUGWOOD.ORG

D. Aspen leafminer larva

pecan serpentine leafminer.

outlined within mine. WHITNEY CRANSHAW

H

I

J

K

H. Leafmine produced by European elm flea weevil. DAVID LEATHERMAN

I. Adult European elm

flea weevils following emergence from leaf mine. WHITNEY CRANSHAW

J. Larva of a European

flea weevil (left) and elm leafminer (right). WHITNEY CRANSHAW

K. Pupa of a European

elm flea weevil exposed within blotch leaf mine. DAVID SHETLAR

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAFMINING WEEVILS, AND BLOTCH LEAFMINING BEETLES

Other Leafmining Weevils About a half-dozen other Orchestes species occur in North America. Apple flea weevil (O. pallicornis) is an eastern species with similar habits and develops on apple, quince, hawthorn, winged elm, and hazelnut. Others develop on various trees and shrubs, including birch, alder, elm, and various rosaceous hosts. Two other genera of North American flea weevils, Isochnus1 and Tachyerges,1 include about a dozen species that also produce similar leaf mines on woody plant hosts. Willow flea weevil (Isochnus rufipes)1 is a small (1⁄12 inch) black weevil that moves in spring to feed on the buds and newly emergent leaves of willow, birch, elm, red maple, aspen, red oak, cherry, and serviceberry. They lay eggs on the underside of leaves, and the larvae develop as leafminers, pupating in the leaf. If infested plants are nearby, the adults may migrate in nuisance numbers into buildings during late summer. Yellow poplar weevil (Odontopus calceatus)1 develops on magnolia, tuliptree, and sassafras in several midwestern and Mid-Atlantic states. Primary damage is caused by larvae, which often feed as groups and produce large blotchlike leaf mines early in the season. Adults feed initially on buds, then move to emerging leaves, chewing small bean-shaped areas. Chewing also occurs on the main veins and can cause tips of leaves to wilt. Eggs are inserted into pits chewed in the main veins of the leaf, and a dozen or more larvae may feed together. When feeding is completed, they pupate in spherical cocoons in the mined leaf. Adults that emerge in midsummer feed for a brief period and then move to winter shelter and go into dormancy. One generation is produced annually. 1

Coleoptera: Curculionidae

LOCUST LEAFMINER

(Odontota dorsalis)1

hosts Larvae develop in black locust and some other leguminous trees, including false indigo and golden chain tree. Adults feed on a wider range of plants that include oak, dogwood, elm, and hawthorn. Damage Larvae feed in the leaves, making irregular blotchlike mines. These mines, which during development may not be readily observed, can be seen most easily from the bottom. Adults feed on the underside of leaves and produce a skeletonizing injury. Distribution Most common in the Mid-Atlantic area, extending into Ohio, but can be found from Alabama and Georgia north into southern Canada. Appearance Adults are moderate-sized beetles, about ¼ inch. They are primarily yellow or yellow-orange with black patterning running down the center of the body and covering most of the hind end. The larvae, found in the leaf mines, are yellowish white, flattened, with dark appendages. Life History and Habits Locust leafminer overwinters as an adult, under fallen leaves and in other protective cover. It may feed on foliage of other trees, notably oak, before moving to black locust. Eggs are laid on the underside of leaves, and the larvae subsequently tunnel. They create a gradually expanding blotch-type mine, usually on the outer edge of leaves. Pupation occurs in the mine. In southern areas of the species’ distribution, a second generation occurs.

218

A. Mating pair of apple flea weevils. DAVID SHETLAR

A

B. Leaf mine on

B

hornbeam produced by apple flea weevil larva. DAVID SHETLAR

C. Leafmine produced

by yellow poplar weevil. DAVID SHETLAR

D. Cocoons surround

the pupae of yellow poplar weevil exposed from leaf mine. DAVID SHETLAR

E. weevils and typical

leaf injuries.

C D

DAVID SHETLAR

E

F. Locust leafminer adults and associated skeletonizing injury produced. DAVID SHETLAR

G. Adult locust

leafminer and two blotch mines produced by larvae. In the mine at the top, the outline of two larvae can be seen. DAVID SHETLAR

F

G

INSECTS THAT CHEW ON LEAVES AND NEEDLES

BLOTCH LEAFMINING BEETLES, AND LEAFMINING FLIES

Other Blotch Leafmining Beetles Poplar blackmine beetle (Zeugophora scutellaris)1 makes large dark blotch mines in poplar and cottonwood. Adults feed on the surface of leaves, making meandering skeletonizing injuries. Basswood leafminer (Baliosus nervosus)1 occurs in much of eastern Canada and the U.S., where it makes blotch leaf mines on basswood and several other deciduous trees. Both species have a single generation, with winter spent in the adult stage. Larvae of the goldenrod leafminer (Microrhapala vittata)1 produces blotch leaf mines in goldenrod. Adult feeding on leaves typically produces numerous shothole or windowpane-type injuries. Eggs are laid in small batches on the leaf underside, each batch typically including about 3 eggs that are covered with feces. The larvae feed gregariously and may completely mine a leaf.  Coleoptera: Chrysomelidae

1

HOLLY LEAFMINERS2 hosts Four Phytomyza species of leafminers are associated with hollies (Ilex spp.). Native holly leafminer (Phytomyza ililocola) prefers American holly and may also attack English and Chinese hollies. Holly leafminer (P. ilicis) only attacks English holly. Inkberry leafminer (P. glabricola) and winterberry leafminer (P. verticillatae) exclusively attack their respective hosts. Damage Larvae of most of these “holly leafminers” produce comma-shaped mines. Each larva starts the mine as a thin linear trail (the first-instar larva) and then forms a blotch mine (the second and third larval instars). Damaged leaves may drop prematurely, especially during the winter and early spring. Adults of many holly leafminers also cause conspicuous injuries. Adult females create puncture wounds with their ovipositor, which is used not only when laying eggs but also more commonly to acquire plant fluids on which to feed. These puncture wounds result in pinhole damage and affected leaves can become distorted and stunted. The inkberry leafminer produces fewer pinholes. Distribution Primarily important in the eastern and southern U.S. where Ilex hosts occur. Some species are also present in the Pacific Northwest. Appearance Larvae are tiny, pale yellow maggots found in the mines. Adults are small gray flies. Life History and Habits The native holly and inkberry leafminer life cycles have been studied, but the others are poorly known. Native holly leafminer adults emerge in mid-May, when the new leaves are about ½ inch long. Females, which are about the size of a fruit fly, mate and begin maturation feeding by making pinholes in new leaves. These females often make a series of pinholes that can severely distort the expanding leaves. Eventually the females will insert eggs into the pinholes. After 1–2 weeks, the egg hatches and the larva makes a small ¼-inch-long mine. This first-instar larva then enters a dormant state and does not resume feeding until October or November. At this time the second-instar larva begins to expand the width of the mine. During freezing temperatures, the larvae stop feeding. By mid- to late April the third-instar larva finishes its development and cuts a small hole in the upper leaf epidermis. Under this hole, the larva pupates. The adults emerge a couple of weeks later. One generation occurs each season. The holly leafminer is suspected to have the same life cycle. Inkberry and winterberry leafminers appear to have two generations per season. 220

C A

B

A. Leaf injuries typical of adult feeding by poplar blackmine beetle.

D

E

B. Adults of the basswood leafminer.

WHITNEY CRANSHAW

DAVID SHETLAR

C. Dark blotch mine produced by

larvae of the poplar blackmine beetle. WHITNEY CRANSHAW

D. Adult of the goldenrod leafminer. DAVID CAPPAERT, BUGWOOD.ORG

E. Leaf mine produced by

goldenrod leafminer.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F

I

G

H

J

F. Leafmines produced by a holly leafminer. DAVID SHETLAR

G. Adult holly leafminer and

feeding wounds on new growth. DAVID SHETLAR

H. Pinhole wounds resulting

from feeding punctures by holly leafminer adult. DAVID SHETLAR

I. Early stage mines on holly. DAVID SHETLAR

K

J. Extensive leafmining damage

to holly. Also present are numerous pinhole feeding wounds and two pupae in the lower center of the photo. DAVID SHETLAR

K. Leafmining damage by

inkberry leafminer. DAVID SHETLAR

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAFMINING FLIES

Spinach Leafminer (Pegomya hyoscyami)1 hosts Spinach, chard, beet, lambsquarter, pigweed Distribution Spinach leafminer is a species of European origin that is now generally distributed in the northern U.S. and Canada. In the western areas the closely related beet leafminer (P. betae) may be more abundant. Damage The immature maggots tunnel through older leaves. The large, dark, blotchy mines that are produced destroy the leaves for use as greens, although effects on plant growth appear to be minimal. Appearance The larvae are pale-colored, generally cylindrical maggots found in the leaf mines. Adults are small (ca. 1⁄5–⅓ inch) gray or grayish brown flies. Life History and Habits The insect overwinters in the soil as a pupa, emerging in midspring. The adult flies lay small masses of white eggs on the underside of older leaves. Upon hatching, the young maggots tunnel into the leaves, where they feed, typically for 2–3 weeks. When full grown, they cut through the leaf, drop to the ground, and pupate in the soil. Several generations may be completed during the season, but activity largely ceases in midsummer, with most damage occurring on the cooler sides of the growing season.

Other Leafmining Flies Beet leafminer (Pegomya betae)1 has a host range that largely overlaps that of the spinach leafminer. It is also native to Europe, but appears more restricted in distribution in North America and is more common in western states and provinces. Life history and feeding injuries to garden plants are similar to spinach leafminer. Several species of leafminers in the genus Phytomyza2 produce blotch mines in various garden flowers. Phytomyza aquilegiana and P. columbinae produce blotch mines in columbine. Phytomyza delphinivora and other species develop in larkspur, delphinium, and aconite. Little is known about the biology of these species, but it appears two generations are normally produced annually. Chrysanthemum, marguerite, daisy, and several other composites may be hosts for P. atricornis or P. chrysanthemi. Blotch mines on many of the same hosts are also produced by Amauromyza maculosa,2 a common species in Florida. Three to six larvae may commonly occur in each mine. Adults make feeding punctures with their ovipositor, and these pinhole spots on leaves can be useful indicators of adult activity. Corn blotch leafminer (Agromyza parvicornis)2 develops in leaves of corn, producing irregular blotch mines, particularly on lower leaves. Several generations can be produced annually but natural controls, particularly several species of parasitic wasps, normally keep populations low so plant damage is insignificant. Grassy weeds, including barnyardgrass and crabgrass, are occasional hosts for this insect.

222

A

A. Spinach leafminer damage to Swiss chard.

B

WHITNEY CRANSHAW

B. Adult spinach

leafminer.

WHITNEY CRANSHAW

C. Egg mass of the

spinach leafminer. WHITNEY CRANSHAW

D. Spinach leafminer

larva exposed from mine on spinach. WHITNEY CRANSHAW

E. Blotch leafmines

C D

in columbine.

E

F

WHITNEY CRANSHAW

F. Adult columbine

leafminer and feeding puncture wounds. WHITNEY CRANSHAW

G. Columbine

leafminer larva exposed from blotch mine. WHITNEY CRANSHAW

H. Columbine

leafminer pupa exposed from blotch mine. WHITNEY CRANSHAW

G H

I. Corn blotch

leafminer damage. Numerous small feeding wounds produced by adults are present. JIM KALISCH, UNIVERSITY OF NEBRASKA

J. Larva of a corn

blotch leafminer outlined within mine.

JIM KALISCH, UNIVERSITY OF NEBRASKA

I

J

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LEAFMINING FLIES Boxwood leafminer (Monarthropalpus flavus)3 produces small blistered blotches in areas of the leaf where larvae feed. Most species of boxwood are affected, and this is often considered the most serious pest of this ornamental plant. This is an introduced insect, currently found in areas of New England and the Mid-Atlantic States. Adults are tiny orange gnatlike flies that lay eggs in mid- to late spring. There is one generation per year. In the spring, leafmining damage can cause the plants to look as though they have received severe winter burn, and damaged leaves drop early. Asparagus miner (Ophiomyia simplex)2 is an introduced species that has spread through most of the East Coast States and is found in some areas of the Midwest. Larvae develop at the base of asparagus stems, mining the tissues. In large numbers they may girdle the stem, causing yellowing and dieback. More damage is thought to occur from incidental spread of Fusarium root-rotting fungi. Adults are tiny, shiny black flies about ⅛ inch long. Conspicuous holes are produced in the foliage of red oak by the oak shothole leafminer (Japanagromyza viridula).2 The adult females make puncture wounds with their sharp ovipositor in newly emergent leaves less than 2 inches expanded to produce fluids on which the flies feed; eggs are eventually inserted into leaves. The developing fly larva develops as a leafminer, producing a small blotch mine that later dries and drops out. As the leaves continue to expand, the holes produced by adult punctures and larval feeding continue to expand, making distinctive shotholes and giving leaves a tattered appearance. Larvae of the elm agromyzid leafminer (Agromyza aristata)2 develop in leaves of American elm. They produce a more serpentine mine than those of other leafminers associated with elms (e.g., European elm flea weevil, elm leafminer). 1

Diptera: Anthomyiidae; 2 Diptera: Agromyzidae; 3 Diptera: Cecidomyiidae

Boxwood leafminer larvae and pupae exposed from within mine. DAVID SHETLAR

224

A

B A. Boxwood leafminer injury. DAVID SHETLAR

B. Boxwood leafminer

adult next to pupal skin. DAVID SHETLAR

C. Mass emergence of

boxwood leafminer adults. DAVID SHETLAR

D. Adult of the oak

C

shothole leafminer.

D

TOM MURRAY.

E. Leafmine and

shothole injuries produced by oak shothole leafminer. DAVID SHETLAR

F. Shotholes in oak

leaves resulting from expansion of feeding puncture wounds by adult oak shothole leafminer. DAVID SHETLAR

G. Leafmines produced

by the elm agromyzid leafminer.

E

DAVID SHETLAR

F

G

INSECTS THAT CHEW ON LEAVES AND NEEDLES

BIRCH LEAFMINER

(Fenusa pusilla)1

hosts Birch. Damage Larvae develop in leaves, creating large brown blotch mines. After the insects exit, the mined areas wrinkle and can be confused with late frost or sun scald damage. Defoliation occurs on heavily damaged leaves. Stresses from repeated defoliation can increase risk of infestation by bronze birch borer. Distribution Birch leafminer is an introduced European sawfly species currently found in the northern half of the U.S. and southern Canada, east of the Rockies. It is particularly damaging in the Midwest. Appearance The mature larvae are ¼ inch long, slightly flattened, and yellowish white in color. They, and their dark droppings, are found in the mined leaf. Adults are black, thick-waisted wasps, about ¼ inch long. Life History and Habits Birch leafminer winters in the soil in the prepupal stage, pupating in spring as soils warm (April). Adults first appear in spring, coincident with when the first leaves are about half grown, and prefer to mate and oviposit on upper leaves in sunny areas. Small oviposition punctures are visible as dark spots, although eggs are not always laid. Larvae hatch and mine out the middle layers of the leaf; several mines may grow together to form one large blotch mine. After 2–3 weeks, the larvae cut exit holes, drop to the ground, and burrow into the soil to make a pupal chamber. After another 2–3 weeks, the second-generation adults emerge and the cycle repeats. Normally there are two generations per year, although if conditions are dry many of the first-generation wasps remain dormant and do not emerge until the second year. As attacks are limited to new foliage, subsequent generations are less damaging and develop primarily in the crown of the tree.

Other Leafmining Sawflies European alder leafminer (Fenusa dohrnii) is a closely related species that produces blotch leaf mines on alder. Hawthorn leafminer (Profenusa canadensis) produces blotchlike mines in the tips of leaves and is particularly common on Crateagus crus­galli, C. persimilis, and C. erectus. Elm leafminer (Kaliofenusa ulmi) is associated primarily with English elm, American elm, and hybrids. Eggs are inserted in foliage in late spring. Early-stage larvae produce serpentine mines that gradually enlarge and turn blotchlike as they mature. Hawthorn leafminer and elm leafminer have only a single generation per year; European alder leafminer may have multiple generations. Blackberry leafminer (Metallus rubi) produces blotchlike mines in blackberry and dewberry leaves. Two generations occur in Connecticut, with the first adults present in May and early June and second-generation adults present in August. Purslane leafminer (Schizocerella pilicornis)2 produces blotch mines in leaves of purslane. Development of the larvae within the mines is rapid, typically taking about 1 week, and pupation occurs in the soil. A half-dozen or more generations may occur annually.  Hymenoptera: Tenthredinidae; 2 Hymenoptera: Argidae

1

226

B

C A. Blotch mine produced by birch leafminer. WHITNEY CRANSHAW

B. Adult birch leafminer ovipositing into leaf. DAVID SHETLAR

C. Early stage leafmines

of birch leafminer. DAVID SHETLAR

D. Birch leafminer larva exposed from mine. WHITNEY CRANSHAW

A

D

E

F

G E. Leafmines produced by

European alder leafminer. WHITNEY CRANSHAW

F. Female hawthorn leafminer

ovipositing into leaf. DAVID SHETLAR

H

G. Typical leafmines of

I J

hawthorn leafminer. DAVID SHETLAR

H. Elm leafminer larvae

feeding within elm leaf. WHITNEY CRANSHAW

I. Blotch leafmine produced

by purslane sawfly. WHITNEY CRANSHAW

J. Purslane sawfly larvae

exposed from mine. WHITNEY CRANSHAW

INSECTS THAT CHEW ON LEAVES AND NEEDLES

LILAC LEAFMINER (Caloptilia syringella)1 hosts Lilac, privet. Rarely ash, euonymus. Damage Larvae first produce a blotch mine on the foliage, then tie and feed on the leaves. The ragged leaves and associated leaf rolling can seriously detract from a plant’s appearance. Distribution Primarily a western species found in northern states and southern Canada. Appearance Adults are small moths (ca. ½ inch long) that fold their wings tubelike over the body at rest. The wings are generally gray with reddish-brown patches, and there is some light striping across the body. Larvae are glossy green and found in mines or folded leaves. Younger larvae are more flattened than older larvae. Life History and Habits Lilac leafminer spends the winter as a pupa or full-grown larva in the mines of dropped leaves. The adult moths emerge in spring after leaves emerge and lay eggs in small groups on the leaves. Newly hatched larvae tunnel directly into the leaf, entering underneath the egg. As they develop and grow larger, they excavate a blotchlike mine, and tunneling by several larvae may coalesce. As the larvae become nearly mature, they leave the leaf mine and tie the edge of the leaf with silk. They continue to feed in the folded leaf and later pupate. There are probably two generations per season.

Other Lepidopteran Leafminers Boxelder leafminer (Caloptilia negundella)1 feeds on boxelder and causes injuries similar to those of lilac leafminer. There are two generations per year, and the life cycle is likely similar to that of lilac leafminer. Azalea leafminer (C. azaleella) is found commonly in the eastern and southeastern U.S. and incidentally in the Pacific States. It is associated with low-growing azalea, and two generations are reported from North Carolina. Nepticula slingerlandella2 is an infrequent pest of cherry and plum but has had historical outbreaks in cherry orchards of the Great Lakes States. Adults emerge from overwintered pupae and lay eggs on the underside of leaves in June. The larvae tunnel under the upper epidermis, so their meandering mines are most visible from the top surface. Caterpillars are about 1⁄5 inch when full grown and opaque greenish white. One generation is produced annually, with winter spent as a pupa in debris around the base of infested trees. In the Pacific States, leaves of hollyleaf cherry are commonly mined by larvae of Paraleucoptera heinrichi.3 Full-grown larvae emerge from the mine, construct a white H-shaped tent of silk on the upper leaf surface, and pupate in this protective structure. In the Pacific Northwest, blotch mines in Laburnum are produced by Leucoptera laburnella.3 Blotchy leaf mines of oak in eastern North America are commonly produced by oak leafminers (Cameraria spp.).1 Depending on the species, mines may be produced by a single larva or by larvae feeding in small groups. Several generations may be produced annually, with the overwintering generation staying in mines of dropped leaves. Cameraria caryaefoliella is a common leafminer of pecan, mining the upper leaf surface. Cameraria species produce blotch mines in other woody plants including hickory, sugar maple, and Ohio buckeye. Throughout the continental U.S. and parts of southern Canada, morning glory leafminer (Bedellia somnulentella)3 mines the leaves of sweetpotato, morning glory, and bindweed. Initial mines are serpentine and later enlarge to become blotchlike. Two generations are produced in the northern U.S. Lyonetia leafminer (Lyonetia speculella)3 has become increasingly common in the mid-Atlantic region since the 1980s. It produces small blotchy mines in young leaves of apple, plum, cherry, birch, and grape. Probably little damage is done since older leaves are not suitable hosts. Larvae are light green, and pupation occurs in a silken “hammock” on the undersurface of the leaf. Multiple generations occur during the year. 228

A

B

C

D

E

F

G H

A. Lilac leafminer injury to common lilac. WHITNEY CRANSHAW

B. Lilac leafminer larvae exposed from leafmine. WHITNEY CRANSHAW

C. Lilac leafminer adult. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Azalea leafminer larva. JOHN A. DAVIDSON, UNIVERSITY OF MARYLAND, BUGWOOD.ORG

E. Adult of a Caloptilia sp. leafminer DAVID SHETLAR

F. Blotch mines produced by oak leafminers.

I

DAVID SHETLAR

G. Larva of an oak leafminer exposed from mine. DAVID SHETLAR

H. Extensive leafmining by Cameraria sp.

leafminers in oak.

ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

I. A larva of a shield bearer, Coptodisca cercocarpella, covered with a circular leaf piece. ROBERT HAMMON, COLORADO STATE UNIVERSITY

Shield bearers (Coptodisca spp.)4 are tiny moths that develop as leafminers, producing small blotch mines. When feeding is completed, they cut a round section of leaf and fashion a small shielded case around themselves in which they pupate. Heavily infested plants may have numerous small holes, similar to those produced by a hole punch. Resplendent shield bearer (C. splendoriferella) is widespread in the U.S. and feeds on apple and cherry. Madrone shield bearer (C. arbutiella) is a common Pacific Coast species associated with madrone and manzanita. Appleleaf trumpet leafminer (Coptotriche malifoliella)5 makes distinctive mines in apple, hawthorn, and crabapple. From the initial point of entry into the leaf, the mine expands to a large blotch, giving the appearance of a trumpet. Apple trumpet leafminer is a native species found in much of the northeastern quadrant of the U.S. and some areas of southeastern Canada.  Lepidoptera: Gracillariidae; 2 Lepidoptera: Nepticulidae; 3 Lepidoptera: Lyonetiidae;

1 4

Lepidoptera: Heliozelidae; 5 Lepidoptera: Tischeriidae

INSECTS THAT CHEW ON LEAVES AND NEEDLES

TENTIFORM LEAFMINERS

(Phyllonorycter spp.)1

hosts Tentiform leafminers are moths associated with many kinds of woody plants, and more than 80 species occur in North America. At least eight native species are associated with either Populus (aspen, poplar, cottonwood) or Salix (willow). Apple and crabapple (Malus) host several species, including some of European origin that are common orchard pests. Celtis (hackberry), Acer (maple), Carya (pecan), and Tilia (basswood) host other commonly encountered tentiform leafmining species. Damage Early instar larvae are sap feeders that produce patches of leaf spotting where mesophyll cells have been gouged and destroyed. Later stage larvae produce a blotch leaf mine on the leaf underside. Silk is spun over the epidermis of the mined area, which later causes the affected area to contract, producing a tentlike pucker. Distribution Among apple infesting species, the spotted tentiform leafminer (P. blancardella), an introduced species, appears to have the widest distribution and is found in almost all apple producing regions. In western orchards other Phyllonorycter1 species predominate. Western tentiform leafminer (P. elmaella) develops in leaves of apple and cherry; P. mispilella feeds on apple, pear, and cherry. Some 17 species of rosaceous plants support apple blotch leafminer (P. crataegella), a species found in the northern U.S. and southern Canada. Species associated with Populus (Phyllonorycter apparella, P. nipigon, P. deserticola, P. populiella) and Salix (P. salicifoliella, P. acanthus, P. mildredae, P. scudderella) can be found across southern Canada and the northern U.S., but are more common in the western regions. Maple leafminer (P. aceriella), which mines the upper leaf surface of red and sugar maples, and P. lucetiella, which makes squarish mines on basswood, are found in eastern North America. Tentiform mines in hackberry result from the activity of P. celtisella. Phyllonorycter caryaealbella produces blotch mines in the lower leaf surface of pecan. Appearance Adults are tiny moths with a wingspan of about ⅓ inch. The wings are patterned with gold, black, and white. Larvae are cream colored and flattened during early stages, developing a more typical caterpillar form and functional legs in later stages. Life History and Habits Life histories of most species have been poorly studied, but a generalized biology is known, based largely on observations of species affecting apple. Adults emerge in spring at bud break, mate, and deposit eggs singly on the underside of young leaves. The first three larval stages feed on the leaf surface, taking sap from parenchyma cells that produce leaf spotting. At the end a small blotch mine is initiated and the last two larval stages enter the leaf and extend the mine as they feed on tissues. A thin layer of silk is produced that covers the outside of the mined area. By mid- to late June, the larvae pupate within the mine. If a second generation is produced, just prior to adult emergence, the pupae wiggle halfway out of the mine, leaving the pupal skin partially extended from the leaf. The number of generations produced is unknown for most species, but two generations are probably typical, with adult flights in late spring and late summer; some species associated with apple have three generations and up to four generations are reported with a species on pecan. All Phyllonorycter spp. spend winter as a pupa within the mines of fallen leaves. Tentiform leafminers are heavily parasitized by many insects. Bird predation of late-instar larvae can also be locally common. Outbreaks are typically of short duration, one to two years at most. Inappropriate insecticide use can prolong outbreaks through adverse effects on biological controls.  Lepidoptera: Gracillariidae

1

230

A

B C

D E

A. Tentiform leafmines on apple. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

B. Upper surface symptom of

tentiform leafminer in apple. DAVID SHETLAR

C. Lower surface symptom of

f

E. Tentiform leafminer

injuries to cottonwood. WHITNEY CRANSHAW

F. Tentiform leafmines

in hackberry.

WHITNEY CRANSHAW

tentiform leafminer in apple.

G. Adult of a tentiform leafminer.

DAVID SHETLAR

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Tentiform leafminer larva in apple leaf.

H. Larval stage of a parasitic wasp that attacks tentiform leafminers.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

DAVID SHETLAR

g H

INSECTS THAT CHEW ON LEAVES AND NEEDLES

NEEDLEMINERS Larvae of the spruce needleminer (Taniva albolineana)1 hollow out the base of spruce needles. Groups of needles are often cut and later webbed together in a small mass; often, several larvae may feed together. Infestation of large trees is usually confined to lower branches, but entire crowns of small trees can be infested and defoliated. Spruce needleminer is widespread through the northern half of the U.S. and southern Canada. Larvae are light greenish-brown caterpillars with a dark head, about ⅜ inch long, and found associated with damaged needles. Spruce needleminer spends the winter as a nearly full-grown larva in a cocoon constructed within mats of webbing and dead needles. It resumes feeding in early spring, becoming full grown in April or May. Adult moths emerge and lay eggs on the needles in late May and June. Eggs are laid in rows, on the underside of year-old needles. Larvae initially mine the interior of needles, and damaged needles are later cut off and bound to the twigs with webbing. Larvae feed throughout the summer, suspending feeding with the onset of cold weather. There is one generation per year. Pine needle sheathminer (Zelleria haimbachi)2 is primarily a western species but does occur in the Great Lakes States and Ontario. Larvae tunnel into the fascicle at the base of needles of several kinds of pines, including lodgepole, jack, ponderosa, and white. Individual larvae may destroy 6–10 bundles of needles in the course of development and may cause dieback of terminals in sustained outbreaks. Larvae overwinter as miners in needles. After shoot elongation, they move to the new growth and tunnel into the base of needles. As they get older, they form a silken tube outside the needles and cut them as they feed. Infested plants can be detected by drooping and faded needles hanging by the silk. The full-grown larvae are tan colored and about ½ inch. They pupate in late spring and early summer. Adults then lay eggs, and the newly hatched larvae then tunnel into needles to overwinter. One generation is produced annually. Various species of Argyresthia are often collectively known as “arborvitae leafminers”3 and mine the needles of arborvitae and cypress, causing tips to brown and die back. In most species, adults emerge in late spring and early summer. Eggs are laid in the tips of 1- or 2-year-old twigs, and the larvae tunnel under leaf scales. They feed as miners for the remainder of their lives and winter as partially grown larvae. Visible symptoms of damage usually appear in winter and are commonly mistaken for winterkill or fungal tip blights, although the presence of tunneling activity is diagnostic. Pupation occurs in spring, usually in the tunnels, although cypress tipminer (A.  cupressella), a western species, exits the needle and spins a cocoon on the foliage. Small holes indicate the emergence of Argyresthia adults or the exiting larvae. Several Coleotechnites4 species develop as needleminers of various conifers and are particularly common in western forests. Most important is ponderosa pine needleminer (C. ponderosae), which has produced several widespread outbreaks in the Mountain States. Adults lay eggs in August, usually in older, previously mined needles. After egg hatch, the larvae move to the new needles and bore near the tip. Larval development and feeding continue until the following spring, when pupation occurs. In eastern North America a species that may attract attention is C. picealla, which occasionally damages spruce and produces small “nests” of mined needles that are webbed together. Other Coleotechnites spp. occur in pines, cypress, junipers, and arborvitae.  Lepidoptera: Tortricidae; 2 Lepidoptera: Yponomeutidae; 3 Lepidoptera: Argyresthiidae; 4 Lepidoptera: Gelechiidae

1

232

B A D C A. Mined needles and associated webbing produced by a spruce needleminer.

E

WHITNEY CRANSHAW

B. Larva of a spruce

needleminer.

THE CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

C. Adult of the spruce

needleminer. DAVID SHETLAR

D. Damage produced by

pine needle sheathminer. DONALD OWEN/CALIFORNIA DEPARTMENT OF FORESTRY AND FOREST PROTECTION, BUGWOOD.ORG.

E. Larva of the pine needle

sheathminer within silken retreat.

F G H

DONALD OWEN/CALIFORNIA DEPARTMENT OF FORESTRY AND FOREST PROTECTION, BUGWOOD.ORG.

F. Damage produced by arborvitae leafminer. DAVID SHETLAR

G. Adult exit hole at base of

needles mined by arborvitae leafminer. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

H. Adult arborvitae leafminer. BRUCE WATT, UNIVERSITY OF MAIN, BUGWOOD.ORG

I

I. Needlemining of pine by a Coleotechnites sp. in Ohio. Exit holes are noticeable at the base of some needles.

J

DAVID SHETLAR

J. Adult of a Coleotechnites sp.

associated with pine in Ohio. DAVID SHETLAR

K. Larva of Coleotechnites

K L

picealla, a needleminer of spruce.

CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

L. Small “nest” of webbed

together needles produced by Coleotechnites picealla, a needleminer of spruce. CONNECTICUT AGRICULTURAL EXPERIMENT STATION, BUGWOODO.ORG

INSECTS THAT CHEW ON LEAVES AND NEEDLES

GALL WASPS THAT DEVELOP ON LEAVES The gall wasp family Cynipidae contains hundreds of North American species, almost all of which make galls on oaks and related plants or roses. All aboveground plant parts are distorted into galls by one or more gall wasps, with galls produced in leaves and twigs often being most conspicuous. Furthermore, a great majority of gall wasps have complex life cycles that involve two different forms, each of which makes a different kind of gall. Several examples of these are included in chapter 4, where gall wasps affecting twigs and shoots are discussed. The types of galls produced by gall wasps can be of extraordinary form, with changes in plant growth resulting in growths that are completely different from the original tissues from which they arose. A great many can have very bizarre forms, with complicated architecture, and these galls often attract attention; however, none of the galls on leaves are considered to cause significant effects on plant health. Perhaps the most spectacular form of galls produced on oak are the oak apples, large parchment-covered galls that are large with spongy or fibrous material in the interior. In the center is a chamber in which the gall wasp larva develops. The largest of the oak apple galls are produced by Amphibolips confluenta1 and A. quercusspongifica, which form galls on the leaves or petioles of red, black, scarlet, and some other oaks in the eastern U.S. The galls may be up to 2 inches in diameter and are dark greenish or brownish, drying to light brown. The related translucent oak gall wasp (A. nubilipennis) makes large round, succulent galls— somewhat resembling a grape—on various red oaks. Other large leaf galls of round form, known variously as “oak apples” or “roly-poly galls” are produced by wasps in the genera Andricus and Atrusca. Examples include succulent oak gall wasp (Andricus palustris), common in the northeastern U.S. on red oak, and antlike gallfly (A. lasius), which makes rounded galls covered by filaments on live oak leaves. One of the galls that attracts particular attention in the northwestern states and parts of the Midwest is produced by jumping oak gall wasps (Neuroterus saltatorius and probably related species).1 They make seedlike galls on the leaves of various white oaks, and the galls later drop from the leaf. The developing wasps in the fallen galls are active and cause the galls to jump about until they lodge in a protected crevice, in a manner similar to a tiny Mexican jumping bean. On the underside of bur oak, N. quercusverrucum produces small galls covered by a dense mat of white plant hairs. Phylloteras poculum1 produces a cluster of pale or red saucerlike galls (“spangle galls”) attached to a slender stalk on the underside of oak leaves. Other Phylloteras species produce galls of more cupped form on the upper surface of oak leaves. Galls of similar form are also produced by some Andricus species of gall wasps. Short spiny hairs emerging from a globular leaf gall are produced by hedgehog gall wasp (Acaraspis erinacei)1 on white oak in eastern states. In California, leaf galls on valley oak covered with stout hairs are distinctive of woollybear gall wasp (Atrusca trimaculosa). Philonix fulvicollis is a species commonly associated with bur oak that produces round leaf galls that are made of multiple sections with tiny spines. Leaf galls of cottony appearance, produced by a proliferation of plant hairs, are common forms produced by various Andricus species. Leaf galls covered with stout spines are typical of various “spined turban galls” produced by Antron species. Spined turban gall wasp (Antron douglasii)1 is a common species on valley, blue, and California scrub oak in the western states. A few Diplolepis species1 produce galls on leaves of rose; others develop on twigs. Typically the leaf galls are rounded, reddish, and spiny. D. nebulosus and rose blistergall wasp (D. rosaefolii) are examples of such species. Spinyrose gall wasp (D. bicolor) makes highly spined galls, usually in clusters, on leaves.  Hymenoptera: Cynipidae

1

234

A

B

C

D

E

F

G H

A. Oak apple gall, cut away. WHITNEY CRANSHAW

B. Roly-poly type gall. DAVID SHETLAR

C. Roly-poly type gall cut away

to show interior and an adult.

i

J

DAVID SHETLAR

D. Translucent oak gall. DAVID SHETLAR

E. Translucent oak gall, cut

away to show interior cell. DAVID SHETLAR

F. Jumping oak galls. DAVID SHETLAR

G. Galls produced by Neuroteras

quercusverrucum on bur oak. WHITNEY CRANSHAW

K

L

H. Hedgehog type of gall. DAVID SHETLAR

I. Hairy gall on leaf midrib produced by gall wasp. WHITNEY CRANSHAW

J. Segmented ball-form gall

produced by Philonix fulvicollis. WHITNEY CRANSHAW

K. Simple midrib swelling type of

gall produced by Callirhytis flavipes. WHITNEY CRANSHAW

M N

L. Adult of Callirhytis flavipes. WHITNEY CRANSHAW

M. Small, spiny leaf gall produced

by a gall wasp on rose. WHITNEY CRANSHAW

N. Bud gall produced by

gall wasp on rose. WHITNEY CRANSHAW

INSECTS THAT CHEW ON LEAVES AND NEEDLES

GALL WASPS THAT DEVELOP ON LEAVES, AND GALL-MAKING FLIES

Other Gall-making Wasps that Develop on Leaves Several dozen Pontania species1 make leaf galls on willow. Willow redgall sawfly (P. proxima) is typical, producing a reddish bean-shaped swelling on the leaves of willow. The insect spends winter in soil or under protective debris. Adults emerge in spring and lay eggs in young, expanding leaves in late spring and early summer. The developing larvae feed on the soft tissues in the gall, later moving into firmer tissues to feed but remaining in the gall. When full grown, they drop to the ground and spin a cocoon. The related species P. s­pomum creates prominent rounded yellow or red swellings on willow leaves that develop in small clusters. Josephiella microcarpae is an introduced species present in Florida and southern California that produces galls on the leaves of Cuban laurel, Ficus microcarpa. The galls are in the form of small leaf blisters, often in groups, and can cause significant leaf distortion.  Hymenoptera: Tenthredinidae; 2 Hymenoptera: Agaonidae

1

GALL-MAKING FLIES THAT DEVELOP ON LEAVES The gall midge family Cecidomyiidae is one that contains many dozens of species that develop on leaves and needles. Adults are inconspicuous midgelike flies, and the maggot-form larvae are found in the galls. These are typically in the form of abnormal swellings, thickenings, and/or stunting of foliage. Other gall midges distort developing buds and flowers (e.g., rose midge, swede midge) or fruit, and these are discussed in chapter 7. Other gall-producing flies, in the families Agromyzidae (leafminer flies) and Tephritidae (fruit flies) develop in twigs and shoots (pages 418). Larvae of the honeylocust podgall midge (Dasineura gleditschiae)1 feed on the developing leaves of honeylocust, causing them to distort into thickened, podlike galls. The galls darken, dry, and drop a few weeks after adults emerge. This defoliation gives a thin appearance to the plant, particularly when most of the leaflets on a leaf are affected. Honeylocust podgall midge spends the winter in the adult stage under protective cover around previously infested honeylocust plantings. The adults move to emerging honeylocust buds as they first start to break. Eggs are laid among the emerging leaves, and the larvae feed on the leaflets, causing them to curl and thicken into the characteristic pod gall. Larvae become full grown in about 3–4 weeks, and pupation occurs in the gall. As the adults emerge, the old pupal skin is often pulled partially out at the gall opening. There are typically three generations per year, with populations usually declining by early July. Later infestations may extend for additional generations where sprout growth continues to be produced or in highly fertile, irrigated sites such as nurseries. Ash bulletgall midge (Dasineura pellex) produces large globular galls on the larger veins of ash leaves. Dasineura pseudacaciae1 induces young leaves of black locust to thicken and fold. Thickened veins on boxelder are changes produced by the developing larvae of the gouty veingall midge (C. negundinis); similar vein thickening on red and sugar maples is produced by maple gouty veingall midge (D. communis) in parts of the Midwest. More modest leaf distortions occur from feeding of the pear leafcurling midge (D. pyri) and apple leafgall midge (D. mali), which can cause a curling distortion along the leaf edge.

236

A D

B

C A. Leaf gall produced by willow redgall sawfly.

E

WHITNEY CRANSHAW

B. Cut away of gall by willow redgall sawfly. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Cut away of gall by willow redgall sawfly. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Gall produced by Pontania s-pomum. DAVID LEATHERMAN

E. Leaf galls produced by a Josephiella

microcarpae on Cuban laurel.

DOUG CALDWELL, UNIVERSITY OF FLORIDA

F

G H

J

F. Honeylocust podgalls. WHITNEY CRANSHAW

I

K

G. Adult of the honeylocust

podgall midge.

WHITNEY CRANSHAW

H. Ash bullet galls. JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Gall produced by grape

tube gallmaker midge. DAVID SHETLAR

J. Larvae of the honeylocust

podgall midge in gall. WHITNEY CRANSHAW

L

K. Pod galls produced by

a Blaesodiplosis species in hawthorn. DAVID SHETLAR

M

L. Gouty veingall. WHITNEY CRANSHAW

M. Gall produced by

Blaesodiplosis crataegifolia in hawthorn. WHITNEY CRANSHAW

N. Larvae of gouty veingall

midge exposed within gall. WHITNEY CRANSHAW

N

INSECTS THAT CHEW ON LEAVES AND NEEDLES

GALL-MAKING FLIES THAT DEVELOP ON LEAVES Grape tumid gallmaker (Janetiella brevicauda)1 develops on wild and cultivated grapes in the northeastern U.S. and southeastern Canada. Round, succulent galls are produced on leaves, petioles, and flower clusters. Three generations are produced annually, with most injury caused by the first, which occurs as flower buds are present. Elongate, pointed galls “tube galls” on grape are characteristic of Schizomyia viticola (grape tube gall maker). Blaesodiplosis crataegifolia produces a ridged thickening between leaf veins of hawthorn. Another Blaesodiplosis species produces large bladderlike galls to form in leaves of hawthorn. The genus Contarinia1 includes several species that produce thickened leaf foldings. Gouty veingall midge (C. negundinis) makes a prominent thickening along the midrib of boxelder maple, in which numerous pale larvae may be found. Ash midribgall midge (C. canadensis) can produce a thickening along the midrib of ash leaves in late spring. Linden wartgall of basswood is produced by C. verrucicola. Leaves and developing seedpods of catalpa may be distorted by catalpa midge (C. catalpae). A Contarinia species that produces a modest folding along the leaf edges of pin oak has been associated indirectly with problems of a biting mite in Nebraska. Pyemotes herfsi,2 known as the oak leaf itch mite, develops as a predator of gall midge larvae but may drop from the trees and bite humans. Ocellate gall midge (Acericesis ocellaris)1 produces distinctive “eyespot” galls on red maple leaves. The galls are yellow margined with red and form on the upper surface of the leaf. Eyespotting of tuliptree leaves is produced by eyespot gall midge (Thecodiplosis liriodendri).1 Distortion and discoloration of rhododendron foliage can result from damage by rhododendron gall midge (Clinodiplosis rhododendri).1 Adults emerge from overwintering pupae and lay eggs on emerging leaves. Multiple generations are produced coinciding with the spring flush of growth, and peak damage is typically caused by the second and third generations. Twisting and distortion of new growth on chrysanthemum may be due to injury by chrysanthemum gall midge (Rhopalomyia chrysanthemi).2 Larvae feeding on buds may result in formation of cone-shaped galls. Fleshy knobbed distortions of the shoot tips of coyote bush (Baccharis pilularis) are produced by baccharis gall fly (R. californica). Violet gall midge (Phytophaga violicola) can produce a leaf edge curl that can develop into a bladder-form gall on African violet. Close to two dozen Caryomyia species1 are associated with leaves of hickory. These “hickory gall midges” produce a wide range of gall forms, many rivaling the complexity of those produced by gall wasps. In the Mountain States, stubby needlegall midge (Contarinia coloradensis)1 produces basal swellings and stunting of ponderosa pine needles. In the Pacific Northwest and Pennsylvania the Douglas-fir needle midge (C. pseudotsugae) is an important pest of Christmas tree plantings. Adults lay eggs in the newly expanding buds in spring, and the larvae develop in the base of needles. Infested needles yellow and then brown and drop prematurely. Winter is spent in the soil as a full-grown larva that pupates the following March and April. One generation is produced annually. Balsam needlegall midge (Paradiplosis tumifex) causes a similar injury to balsam fir. A common gall of pinyon grown in ornamental plantings is pinyon spindlegall midge (Pinyonia edulicola).1 It produces a basal swelling of new needles, in which as many as a dozen or more pale orange larvae develop. Needles turn brown and drop the following year. Basal swelling combined with needle stunting is produced by pinyon stunt needlegall midge (Janetiella spp.).1 Cypress twiggall midge (Taxodiomyia cupressiananassa) cause the buds of pond cypress and baldcypress to become grossly enlarged. One generation is produced in the northern areas, with larval stages surviving winter within the dropped galls. In parts of Florida two generations may occur.  Diptera: Cecidomyiidae; 2 Trombidiformes: Pyemotidae

1

238

C D A E

B

F

G

A. Ash midrib gall. WHITNEY CRANSHAW

B. Leaf edge curl produced by

a Contarinia species of gall midge of pin oak.

JIM KALISCH, UNIVERSITY OF NEBRASKA

H

C. Larvae of a Contarinia species

I

of gall midge that produces a leaf edge curl of pin oak. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Bull’s-eye type gall produced

by ocellate gall midge. DAVID SHETLAR

E. Fleshy gall of coyote bush

J

terminal produced by the baccharis gall fly.

K

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

F. Violet gall midge. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

G. Gall produced by Caryomyia

subulata on hickory. TOM MURRAY

H. Gall produced by Caryomyia tubicola on hickory. TOM MURRAY

L M

N

I. Gall produced by Caryomyia persicoides on hickory. TOM MURRAY

J. Needle gall of pine produced

by a Contarinia species of gall midge. DAVID SHETLAR

K. Douglas-fir needle gall. WARD STRONG, BC MINISTRY OF FORESTS, BUGWOOD.ORG

L. Balsam needle gall. DAVID SHETLAR

O P

M. Balsam needle gall with

midge larva exposed. DAVID SHETLAR

N. Cypress twiggalls. DAVID SHETLAR

O. Pinyon spindlegalls. WHITNEY CRANSHAW

P. Adult emergence of pinyon

spindlegall midge. WHITNEY CRANSHAW

CHAPTER THREE

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

Insects in two orders (Hemiptera, Thysanoptera), along with several families of mites, feed by sucking fluids from plants. Plant injuries produced differ completely from those produced by insects with chewing mouthparts, and many produce distinct symptoms related to how the mouthparts function and what site of the plant they feed. Excreted waste materials can also be useful for diagnosis. Insects in the order Hemiptera have “piercing-sucking” mouthparts in the form of long stylets that penetrate the plant; within the stylet bundle is a channel for introduction of saliva and a food canal for removing the fluids on which the insect feeds. Many of the most common insects in this order (e.g., aphids, soft scales, mealybugs, psyllids, many leafhoppers and treehoppers) use the mouthparts to reach the phloem of the plant, extracting the sugar-rich sap. Usually, individual insects with this habit produce little cell injury, but when high numbers are sustained, plants may show wilting, stunted growth, and color changes. Leaf curling can also be produced by some insects, notably aphids, which feed on emerging leaves; however, phloem feeding insects also normally excrete sugary honeydew as a waste product, which can be very useful for diagnosis. Furthermore, surfaces on which honeydew lands and persists support growth of sooty mold fungi. Waste sugars may also be converted into wax that may cover the body or be expelled in the form of small pellets or threads. Other insects (e.g., some leafhoppers, lace bugs, thrips) and spider mites remove contents from interior parenchyma cells of the leaves. Often this results in light spotting, known as stippling. Excreted waste associated with this feeding is often in the form of small dark droplets, known as tar spots. More extensive damage is done by insects that feed in a manner known as “lacerate and flush” where large numbers of cells are killed during feeding events. This can produce highly visible spots of dead tissue, and when feeding of this type occurs on emerging growth, leaves become distorted. Plant bugs, along with many stink bugs and leaffooted bugs, are common insects that feed in this manner. Mouthparts of thrips and spider mites are quite small and function differently from those of hemipterans. Both groups puncture surface cells in the course of feeding, which results in scarring wounds from thrips and small stippling wounds from spider mites. Because of their small size, eriophyid mites are limited to feeding on only the outer epidermal cells, producing leaf bronzing when in high populations. 240

B

C

D

A–C. (A) Aphids, (B) leafhoppers, and (C) squash bugs are representative insects in the order Hemiptera that feed on fluids from plants using piercing-sucking mouthparts. A, B DAVID SHETLAR. C WHITNEY CRANSHAW

D. Sticky honeydew is the waste

fluid excreted by insects, such as soft scales, that suck fluids from the phloem. WHITNEY CRANSHAW

E. Wax may be excreted or used to

cover the body of many insects, such as woolly aphids, that suck fluids from the phloem of plants.

A E

F

WHITNEY CRANSHAW

F. Insects that suck fluids from the

xylem of plants, such as spittlebugs, produce watery excretions. JEFF HAHN, UNIVERSITY OF MINNESOTA

G. True bugs, such as plant bugs,

which use their mouthparts in a “lacerate and flush” manner often cause areas of localized cell death at feeding sites. DAVID SHETLAR

H. Thrips have mouthparts that

G H

penetrate and remove the fluid from plant cells, producing silvery scarring injuries. WHITNEY CRANSHAW

I. The old exoskeletons of spider

mites, as well as the insects that feed with sucking mouthparts, remain after molting and can often be helpful signs to diagnose their presence. WHITNEY CRANSHAW

J. Leaf bronzing is a common

response to injuries produced by spider mites and eriophyid mites, which damage surface cells. WHITNEY CRANSHAW

I

J

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

WHITEFLIES Whiteflies (Aleyrodidae family) are primarily tropical or subtropical insects. Several species survive year-round in southern areas that rarely freeze, but in cooler areas survival over winter is limited to plants grown indoors or in protected sites. Adults are small insects (ca. 1⁄10 inch), typically covered with powdery whitish wax. Immature stages of whiteflies are scalelike, feeding on sap from plants and rarely moving after the first stage. Whiteflies pass through a unique final development stage that does not feed, sometimes termed a “pupa,” from which the adults emerge.

Greenhouse Whitefly (Trialeurodes vaporariorum)1 hosts Greenhouse whitefly has a wide host range and is known to develop on more than 250 ornamental and vegetable plants. Poinsettia, hibiscus, nicotiana, aster, calendula, cucumber, lantana, tomato, grape, ageratum, bean, and begonia are among the commonly infested plants. Damage Greenhouse whitefly sucks sap from the plant, primarily from the phloem. Heavy infestations cause decline of plant vigor. Stunting, yellowing of foliage, and premature leaf drop are among the symptoms of injury. Infestations are also associated with production of honeydew excreted by the whitefly during feeding. Distribution Greenhouse whitefly is found worldwide and the most common species associated with greenhouses and houseplants. Greenhouse whitefly cannot survive winter outdoors in areas with freezing winter temperatures but is commonly annually introduced into gardens on infested transplants. Appearance All the immature stages of greenhouse whitefly are inconspicuous and easily overlooked. They are usually pale in color, almost translucent, and superficially resemble certain scale nymphs. Late-stage nymphs and the nonfeeding pupae may have numerous thin waxy threads along the sides of the body, giving them a somewhat spiny appearance. The spininess of the immature stages is variable and affected by population density and the hairiness of the leaf surface. Adults have nearly pure white wings because of a white waxy coating on them; the wings are held rooflike over the abdomen. Life History and Habits Eggs are attached to leaf undersurfaces and are a creamy yellow color before darkening after 24 hours. Females prefer to attach eggs to the youngest leaves, often in a semicircular pattern. Egg hatch typically occurs within 5–7 days, and the newly hatched nymphs move a short distance before flattening themselves against the leaf to feed. All remaining immature stages of greenhouse whitefly are immobile. There are three nymphal stages that feed on the plant, spaced at 2- to 4-day intervals, followed by a nonfeeding “pupal” stage lasting almost a week. Under highly favorable conditions, a generation of greenhouse whitefly can take as little as 3–4 weeks to complete. Each female is capable of laying 400 eggs over a period of up to 2 months, although usually far fewer eggs are produced.

Other Whiteflies Sweetpotato whitefly (Bemisia tabaci)1 was known to occur in the southern U.S. for more than a century but was not a serious pest. In the mid-1980s, however, a new strain of this insect, known as biotype B, became established. This strain rapidly spread across the southern U.S. and developed into a far more serious pest because of its wider host range, ability to vector plant viruses, and resistance to several categories of insecticides. Furthermore, it appears to have completely replaced the former strain (biotype A) previously present in North America. 242

B A. Greenhouse whiteflies. WHITNEY CRANSHAW

B. Greenhouse whitefly eggs and young nymphs.

A C D

JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Mixed life stages (hatched eggs, nymphs)

of greenhouse whitefly. WHITNEY CRANSHAW

D. Last nymph (“pupa”) of greenhouse whitefly. DAVID SHETLAR

E. Adult and nymphs of greenhouse whitefly. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Sweetpotato whitefly. DAVID SHETLAR

G. Mixed life stages of sweetpotato whitefly. DAVID SHETLAR

H. Newly emerged adult of sweetpotato whitefly. DAVID SHETLAR

E

F

G

H

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

WHITEFLIES Sweetpotato whitefly biotype B has an extremely wide host range, including poinsettia, hibiscus, chrysanthemum, tomato, pepper, squash, cucumber, cotton, bean, eggplant, cabbage, watermelon, broccoli, potato, and peanut. As with other whiteflies, adults and nymphs remove sap while feeding, causing reduction of plant vigor during heavy infestations. However, introduced saliva has some toxic effects, producing disorders such as silvering of squash foliage, yellowing of lettuce, and whitening of roots and stems of carrot and broccoli. Affected tomato may also show irregular ripening. These symptoms have also led to the name “silverleaf whitefly.” Sweetpotato whitefly can also transmit a few plant viruses, including those associated with tomato yellow leaf curl, tomato mottle, and bean golden mosaic. Sweetpotato whitefly biotype B is a common insect in greenhouses. It is generally similar in appearance to greenhouse whitefly but has a slightly more yellowish body, and the adults tend to wrap their wings around their abdomens when at rest. The last instar (pupa) is the most distinguishing form, being teardrop-shaped, lacking waxy spines, and being more flattened than that of greenhouse whitefly. More recently an additional biotype, biotype Q, has been detected in greenhouse plantings in many North American sites. However, only recently have outdoor reproducing populations been observed, in southern Florida. The primary difference between the Q and B biotypes is in susceptibility to certain insecticides used in whitefly management. Bandedwinged whitefly (Trialeurodes abutilonea)1 is a close relative of greenhouse whitefly but rarely a pest. Adult bandedwinged whiteflies can be differentiated by the presence of two smoky gray, zigzag bands on the wings; pupae are distinguished by a dark band down the middle of the body. Poinsettia, geranium, hibiscus, and petunia are the most common hosts in greenhouses. In southern states this species may breed outdoors on various weed hosts as well as on cotton and some ornamentals. Mulberry whitefly (Tetraleurodes mori)1 is found throughout most of the U.S. although rarely as a pest. Common hosts include mahonia, hackberry, mountain laurel, sweetgum, maple, dogwood, sycamore, citrus, and mulberry. The last-stage nymph (“pupa”) has an unusual and conspicuous appearance, being shiny black with a white fringe. Multiple overlapping generations are produced during the growing season, and the pupa is the overwintering stage that can withstand freezing temperatures. A species of similar appearance is azalea whitefly (Pealius azalaeae),1 an introduced species now found throughout the southeastern U.S. wherever azalea is grown. Rhododendrons may host rhododendron whitefly (Dialeurodes chittendeni).1 Ash whitefly (Siphonius phillyreae)1 is an introduced insect discovered in southern California in the late 1980s that has since spread to many states. Hosts include ash, mulberry, crabapple, flowering pear, serviceberry, western redbud, crape myrtle, tuliptree, lilac, pyracantha, and privet. Severe infestations, with associated problems of honeydew production and sooty mold, occurred shortly after its introduction. Subsequent establishment of the parasitic wasp Encarsia inaron has since had a great effect on suppressing populations.

244

B C

A

D E

F

A. Silverleaf symptom associated with sweetpotato whitefly, strain B. ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

B. Irregular ripening of tomato fruit

associated with sweetpotato whitefly, strain B. JOHN CAPINERA, UNIVERSITY OF FLORIDA

C. Bandedwinged whitefly. RONALD SMITH, AUBURN UNIVERSITY, BUGWOOD.ORG

D. Nymphs of bandedwinged whitefly. TOM MURRAY

E. Mulberry whitefly. WHITNEY CRANSHAW

F. Nymphs of rhododendron whitefly. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

G. Ash whitefly adult. ROBIN ROSETTA, OREGON STATE UNIVERSITY

H. Ash whitefly, last-instar nymphs (“pupae”). ROBIN ROSETTA, OREGON STATE UNIVERSITY

G

H

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

WHITEFLIES Citrus blackfly (Aleurocanthus woglumi)1 is an important whitefly associated with citrus in southern Florida. As it feeds it produces considerable amounts of honeydew, further promoting unattractive sooty molds on leaves and developing fruit. As in mulberry whitefly, the last-stage nymph is shiny black with a white wax fringe. Adults are slate blue, considerably darker than most common whiteflies. Citrus whitefly (Dialeurodes citri)1 is found throughout the southern U.S. It can be an important pest of citrus but develops on a wide range of hosts including ivy, gardenia, lilac, and privet. Development is continuous, with generations being completed in about 2 or 3 months during the growing season. Winter in the northern areas of the range is spent as late-stage nymphs on leaves. Woolly whitefly (Aleurothrixus floccosus)1 also develops on citrus, as well as on Eugenia. It is found in areas of southern California and Florida. Woolly whitefly became a serious pest following its accidental introduction around 1909 until several parasitic wasps were established that since have provided excellent biological control. As the name suggests, the body of the nymph is covered in long, loose waxy threads. Giant whitefly (Aleurodicus dugesii)1 is a non-native species of spreading distribution that is substantially larger than most whiteflies. Giant whiteflies tend to reproduce on the same leaf on which they developed, causing clustering of colonies, and waxy filaments dislodged from the body may spread across the leaf surface. Furthermore, while laying eggs they make distinct waxy spirals on the underside of leaves. Giant whitefly has a very wide host range of ornamental plants, including begonia, hibiscus, mulberry, and giant bird-of-paradise. Banana, some citrus, and many vegetables are other hosts. More than 60 species of plants serve as hosts of the rugose spiraling whitefly (A. rugioperculatus), with gumbo-limbo, coconut palm, and Calophyllum among the plants that are most heavily infested in southern Florida. The species, as well as other “spiraling whiteflies” (Aleurodicus spp.) lay their eggs in a distinctive spiral pattern, mixed with wax, on the underside of leaves. In addition to causing plant stresses that produce foliage yellowing and leaf drop, rugose spiraling whitefly also excretes large amounts of honeydew. Iris whitefly (Aleyrodes spiraeoides)1 is reportedly common in California and sometimes injurious to iris and gladiolus. It has a wide host range including many vegetables, strawberry, and cotton. Adults have a slightly darkened dot on each wing. Eggs are laid in distinct circles, and fine powdery wax is produced about the eggs and nymphs on the leaf. Brassica whitefly or “cabbage whitefly” (Aleyrodes proletella) is a European species originally discovered on the East Coast but which has since spread extensively across the northern U.S. and into many areas of Canada. This whitefly can infest most cabbage family plants and has been a problem mostly on kale. Sowthistle (Sonchus) is a noncrop plant that also commonly supports this insect. Other whiteflies have recently become established in south Florida. Ficus whitefly (Singhiella simplex)1 has developed into a potentially serious pest of Ficus spp., particularly weeping fig (F. benjamana). Bondar’s nesting whitefly (Paraleyrodes bondari)1 has also been primarily associated with ficus, although it has a potentially wider range of host plants. 1

Hemiptera: Aleyrodidae

246

A

B

C

D

E

F

G H

I

K J

L

A. Citrus blackfly.

E. Citrus whitefly nymphs.

FLORIDA DIVISION OF PLANT INDUSTRY, BUGWOOD. ORG

FLORIDA DIVISION OF PLANT INDUSTRY, BUGWOOD. ORG

B. Citrus blackfly eggs.

F. Woolly whitefly.

FLORIDA DIVISION OF PLANT INDUSTRY, BUGWOOD. ORG

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SERVICE, BUGWOOD.ORG

C. Citrus blackfly nymphs.

G. Woolly whitefly nymphs.

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SERVICE, BUGWOOD.ORG

FLORIDA DIVISION OF PLANT INDUSTRY, BUGWOOD. ORG

D. Citrus whitefly.

H. Giant whitefly.

LYLE J. BUSS, UNIVERSITY OF FLORIDA, BUGWOOD.ORG

DAVID CAPPAERT

I. A spiraling whitefly (Aleurodicus species). DAVID SHETLAR.

J. Brassica whitefly. ROBIN ROSETTA, OREGON STATE UNIVERSITY

K. Brassica whitefly nymphs. ROBIN ROSETTA, OREGON STATE UNIVERSITY

L. Iris whitefly. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

APHIDS More than 1,300 species of aphids (Aphididae family) occur in North America, including scores of species that are associated with and may be damaging to yard and garden plants. All are small, rarely exceeding 1⁄12 inch, but they reproduce prolifically and frequently become extremely abundant. Normally wingless adult forms are produced, but aphids can produce both winged and wingless adults. Production of winged forms increases when conditions exist that favor leaving the plant, such as overcrowding and decline of plant quality. Winged forms are also produced at certain times of year, often in response to changes in day length, prompting them to move to new host plants. Aphids feed by sucking sap from the phloem of plants and can cause several kinds of injuries. In high numbers they can cause a decline in plant vigor, leaf yellowing, and wilting. Aphids also excrete large amounts of honeydew, which may become a significant nuisance, attracting nuisance flies and wasps and supporting growth of associated sooty molds. Aphids feeding on new growth of some plants may cause leaf curling or discoloration. In addition, some aphids can transmit viruses that produce plant disease. Normal aphid reproduction is asexual. Females produce an egg, without mating, but the egg is retained internally, hatches, and the nymph emerges as a live birth. Furthermore, the daughter aphid at birth has already begun to mature her own eggs—literally born pregnant. The ability of aphids to reproduce asexually (parthenogenesis) and hatch eggs internally to give live birth (ovoviviparity) helps aphids to build large populations rapidly and requires only a single foundress to colonize a new plant. In most areas of North America, however, conditions can occur that are adverse to aphid reproduction, notably freezing temperatures that kill host plants and are lethal to aphids. Adapting to this condition, most aphid species have shifted their habit so that at the end of the growing season they lay eggs externally that can survive between seasons. The production of eggs is preceded by a generation in which special winged forms of both males and females are produced (sexuales). These meet and mate on the winter host plant, producing oviparae, special forms that lay eggs that survive winter. An aphid life cycle that involves production of males during one generation, followed by the production of an egg, is called a holocyclic life cycle. When conditions are continuously favorable for reproduction, the production of sexual forms and overwintering eggs is dispensed with, and asexual reproduction occurs year-round. Some insects, such as cabbage aphid, normally reproduce year-round on outdoor host plants and never produce an egg, having an anholocylic life cycle. Also, some aphids may shift to an anholocyclic life cycle in indoor conditions. For example, green peach aphid (Myzus persicae) and potato aphid (Macrosiphum euphorbiae) may reproduce indoors year-round strictly through parthenogenesis but produce overwintering eggs on outdoor plants. Many species of aphids compound the complexity of their life cycles by alternating host plants during the growing season. In this type of life cycle, termed two-host or heteroecious holocycly, eggs are produced on a winter host, and spring populations arising after egg hatch occur on this host. They then disperse in late spring to an alternate, summer host. About half the aphids in North America have this habit of alternating between host plants in winter and summer. Those that produce overwintering eggs but do not alternate hosts in winter and summer are said to have an autoecious holocyclic life cycle.

248

A

B

C A. Winged and wingless forms of an aspen aphid.

D

WHITNEY CRANSHAW

B. Norway maple aphids

and associated honeydew. WHITNEY CRANSHAW

C. Cottonwood aphid giving birth. WHITNEY CRANSHAW

D. Honeydew and cast skins

of green peach aphid. WHITNEY CRANSHAW

E. Sooty mold on sidewalk under

linden tree infested by linden aphid. WHITNEY CRANSHAW

F. Mating pair of aphids

on sycamore.

E

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F

G. Egg producing forms

(oviparae) and eggs of a Ceruraphis species of aphid. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H. Overwintering egg of the mealy plum aphid.

G

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

I. Life cycle of an aphid that has host alternation (heteroecious, holocyclic). late summer female produces winged migrant forms of both sexes

H

male with special egg-producing form (oviparae) on winter host

I

continual summer generations develop on summer hosts

winged or wingless female forms are present

eggs on winter host through winter

stem mother hatches from egg in spring

winged and wingless females on winter host, winged forms disperse to summer hosts

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

APHIDS

Green Peach Aphid (Myzus persicae)1 hosts Winter (primary) hosts include peach, apricot, and rarely certain cherries and plums. Summer hosts include more than 200 species of herbaceous plants, many of them vegetables and ornamentals. Green peach aphid is also one of the most common damaging aphids of greenhouse crops. Damage On winter hosts such as peach and apricot, spring generations can produce serious leaf curling. A wide variety of vegetables, herbs, and other herbaceous plants are colonized during the growing season. Green peach aphid is also adapted to developing on many plants grown indoors and is one of the most important greenhouse aphids. Leaf curling symptoms produced by green peach aphid are restricted to certain species of Prunus in spring. However, in high population green peach aphid can cause stunting, wilting, and premature leaf drop and produce abundant amounts of excreted honeydew. Green peach aphid is also an efficient vector of many plant viruses including potato virus Y, cucumber mosaic, plum pox, and bean common mosaic. Strains of green peach aphid that are highly resistant to many insecticides have become common in many areas. Distribution Green peach aphid occurs throughout North America, both outdoors and as a common greenhouse pest. Appearance Nymphs and wingless adults are usually straw colored, sometimes pale green. Nymphs that will ultimately transform to winged forms may be pale orange or red. Winged females have a black head and dark patch on the abdomen. Life History and habits Outdoors in cold climate areas, green peach aphid alternates between a primary winter host and various secondary summer hosts. On the primary host, winter is spent as eggs laid near buds of peach or apricot. Eggs hatch following bud break to produce wingless females (first generation). Upon reaching adulthood they give live birth, producing two or three generations on the winter host. In the last spring generation, winged forms are produced that abandon the winter host and migrate to herbaceous summer host plants. On summer hosts, individual aphids may become mature within 2 weeks after birth. Under optimal conditions females may produce two or more young per day for about 2–3 weeks. Most adults are wingless, but some winged forms occur, particularly when colonies become crowded. A dozen or more generations may be produced during the growing season. During late summer and early fall, new winged forms (fall migrant males and females) are produced that migrate to the Prunus winter hosts. After mating, the overwintering eggs are laid. In greenhouses and areas where warm temperatures occur throughout the year, the forms of green peach aphid associated with the Prunus winter hosts do not occur. Instead reproduction is continuous from females that give live birth without mating. Adults may be winged or wingless. Hemiptera: Aphididae

1

250

B

C

E

F

G H

I

A D

J

A. Green peach aphid, winged and wingless stages. WHITNEY CRANSHAW

B. Green peach aphid colony, showing range of color. WHITNEY CRANSHAW

C. Overwintering egg of

the green peach aphid.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

K

L

D. Green peach aphid hatched from overwintered egg (fundatrice) and nymphs. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Leaf curling produced by

green peach aphid. WHITNEY CRANSHAW

F. Black cherry aphids. WHITNEY CRANSHAW

G. Currant aphids. WHITNEY CRANSHAW

H. Spirea aphids. WHITNEY CRANSHAW

I. Black bean aphid on euonymus. DAVID SHETLAR

J. Symptoms produced by

snowball viburnum aphid. WHITNEY CRANSHAW

K. Symptoms produced

by leafcurl plum aphid. WHITNEY CRANSHAW

L. Rosy apple aphid colony. WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

APHIDS SOME COMMON APHIDS IN NORTH AMERICA THAT ALTERNATE BETWEEN PRIMARY (WINTER) AND SECONDARY (SUMMER) HOST PLANTS1 SCIENTIFIC NAME COMMON NAME

PRIMARY HOST

SECONDARY HOST

Aphis citricola2

Spirea aphid

Spirea

Citrus, apple, pear

Aphis fabae

Bean aphid

Euonymus, viburnum

Bean, beet, cucumber, carrot, lettuce, artichoke, more

Aphis gossypii3

Cotton/melon aphid

Catalpa, rose of Sharon

Many vegetables, flowers, subtropical/ tropical shrubs

Aphis helianthi

Sunflower aphid

Dogwood

Sunflower, pigweed, four o’clock, ragweed

Aphis nasturtii

Buckthorn aphid

Buckthorn

Potato, cucurbits, thistle, many garden flowers

Brachycaudus cardui

Thistle aphid

Plum

Thistle

Brachycaudus helichrysi

Leafcurl plum aphid

Plum

Various Compositae, Boraginacae

Calopha graminis

Elm

Grass (roots)

Calopha ulmicola

Elm cockscomb aphid

American and red elm

Grass (roots)

Capitophorous eleagni

Oleaster-thistle aphid

Russian olive, oleaster

Globe artichoke, thistle

Cavariella aegopodii

Willow-carrot aphid

European willows

Carrot, parsley, dill, coriander

Ceruraphis eriophori

Viburnum

Sedge

Ceruraphis viburnicola

Snowball aphid

Snowball viburnum

Sedge

Cryptomyzus ribis

Currant aphid

Currant, gooseberry

Motherwort, marsh betony

Dysaphis plantaginea

Rosy apple aphid

Apple, pear

Narrow-leaved plantain

Eriosoma americanum

Woolly elm aphid

Elm

Amelanchier (roots)

Eriosoma crataegi

Woolly hawthorn aphid

Elm

Hawthorn

Eriosoma lanigerum

Woolly apple aphid

Elm

Apple, crabapple, mountain-ash, hawthorn

Eriosoma pyricola

Woolly pear aphid

Elm

Pear

Beech blight aphid

Beech

Cypress (on roots year-round)

Hamamelistes spinosus

Spiny witch-hazel aphid

Witch-hazel

Birch4

Hyadaphis crategi

Carrot root aphid

Honeysuckle

Carrot, parsley, fennel, celery

Hyalopterus pruni

Mealy plum aphid

Apricot, peach, plum

Phragmites

Hysteroneura setariae

Rusty plum aphid

Common plum

Numerous grasses, small grains

Potato aphid

Rose

Potato, tomato, many other garden plants

Rose grass aphid

Rose

Grass, corn

Mordwilkoja vagabunda Poplar vagabond aphid

Populus (deltoides group)

Loosestrife

Myzus cerasi

Black cherry aphid

Cherry

Wild crucifers, bedstraw

Myzus persicae

Green peach aphid

Peach, plum, apricot

Pepper, cabbage, potato, spinach, many other vegetable and ornamental plants

Nasonovia ribisnigri

Red lettuce aphid

Currant, gooseberry

Lettuce, chicory, radicchio

Grylloprociphilus imbricator

Macrosiphum euphorbiae Metolophium dirhodum

252

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

APHIDS

SCIENTIFIC NAME COMMON NAME

PRIMARY HOST

SECONDARY HOST

Nearctaphis bakeri

Clover aphid

Hawthorn, quince,

Clover, sweetclover, apple, pear

Nearctaphis crataegi-

Long-beaked clover aphid

Pyracantha, hawthorn, flowering quince

Red clover

Woolly alder aphid

Maple

Alder

Pemphigus bursarius

Lettuce root aphid

Poplar

Roots of lettuce, endive, chicory, dandelion, sowthistle, some other weeds

Pemphigus populivenae

Sugarbeet root aphid

Narrow-leaved cottonwood

Roots of beet, many garden plants

Phorodon humuli

Hop aphid

Plum, apricot

Hops, cannabis

Prociphilus americanus

Ash

Fir (roots)

Rhopalosiphum insertum Apple grain aphid

Apple, pear, hawthorn

Small grains, grasses

Rhopalosiphum

Waterlily aphid

Apricot, almond, other Prunus spp.

Waterlily, buttercup, knotweed

Rhopalosiphum padi

Bird cherry-oat aphid

Prunus spp.

Corn, ryegrass, oat, other grasses

Thecabius lysimachiae

Moneywort aphid

Black poplar

Moneywort

foliae Paraprociphilus tessallatus

nymphaeae

Thecabius populiconduplifolius

Folded-leaf poplar aphid Cottonwood, poplar

Buttercup

1

All species on this list commonly produce overwintering eggs and have a heteroecious holocyclic life cycle.

2

May be known as green citrus aphid when associated with citrus.

3

In much of the southern half of U.S. and in greenhouses, reproduces continuously in normal asexual manner without use of alternate primary hosts.

4

Alternates between two woody plants where it can overwinter as an egg (on witch-hazel) or hibernating female (on birch).

A

B

C

D

E

A. Thistle aphid colony. WHITNEY CRANSHAW

B. Willow-carrot aphids on dill. WHITNEY CRANSHAW

C. Mealy plum aphid colony. WHITNEY CRANSHAW

D. Waterlily aphids. WHITNEY CRANSHAW

E. Bird cherry-oat aphids. JIM KALISCH, UNIVERSITY OF NEBRASKA

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

APHIDS

Cotton/Melon Aphid (Aphis gossypii)1 hosts A wide range that includes hundreds of plants. Among garden plants, cotton/melon aphid is particularly damaging to melon, cucumber, squash, and related vine crops. However, it is also commonly found on plants such as pepper, eggplant, spinach, asparagus, okra, hibiscus, crape myrtle, bougainvillea, pittosporum, and many tropical and subtropical shrubs. Cotton/melon aphid is also one of the most common aphid pests of greenhouse crops. Damage Sap feeding can cause wilting, yellowing, and in extreme cases, death of older leaves. Infestation of new growth results in leaf curling. In some vegetable production areas, cotton/melon aphid is often most important because of its ability to readily transmit many viruses, including cucumber mosaic virus, watermelon mosaic virus 2, and zucchini yellow mosaic virus. Many populations of cotton/melon aphid have developed high levels of resistance to insecticides, further complicating management. Distribution Cotton/melon aphid is cosmopolitan and can occur throughout North America but is particularly damaging in the southern and southwestern U.S. Appearance Wingless females are about 1⁄16 inch and usually a mottled light green. They can vary, however, from pale yellow to dark green or almost blackish. A light coating of wax gives them a dull appearance. Winged adults have a black head and thorax, yellowish-green abdomen, and light gray wings. Life History and Habits In the southern U.S. and in greenhouses, reproduction occurs continually as long as temperatures allow. Unlike most aphids, cotton/melon aphid thrives under warm conditions. Optimal temperatures are in the range of 70–80° F, and the life cycle may be completed in as little as 1 week. In northern areas, cotton/melon aphid may produce an overwintering egg that is laid on catalpa or rose of Sharon. When these eggs hatch in spring, there are usually two generations on the winter host before the species moves to vegetables, flowers, and other herbaceous plants. In the south and in greenhouses, eggs are not produced and continual generations occur year-round.

Cabbage Aphid (Brevicoryne brassicae)1 hosts Cabbage aphid feeds solely on crucifers and can be damaging to broccoli, cabbage, Brussels sprout, cauliflower, canola, and other plants in the mustard family (Brassicaceae). Damage Large numbers of cabbage aphids removing sap retard plant growth. Infestation of new growth distorts heads and produces severe leaf curl. The presence of cabbage aphid as a contaminant can be very important, particularly with Brussels sprout. Flowers and seedpods may produce poorly. Distribution Cabbage aphid is present throughout North America. Appearance Mature females are grayish green with a dark head and dark cornicles. A double row of dark bars is present on the back, but the entire body is covered with fine powdery wax. Winged forms have a single row of dark dorsal bars and dark wing veins. Cabbage aphids are about 1⁄12 inch long. After a molt, the powdery wax covering is absent, allowing markings to be visible. Wax is again produced shortly after the aphids resume feeding. Life History and Habits In southern areas, reproduction can be continual, with adult females giving live birth as long as temperatures permit. There are three nymphal stages followed by the adult form, and the complete life cycle can be completed in less than 2 weeks under optimal conditions. The great majority of adults are wingless unless host plants greatly deteriorate. They may live for about a month, during which time they can produce more than 80 young. Winged forms are weak fliers but readily infest nearby plantings. Relatively few young (ca. 6–10) are produced by winged females. In northern areas where winter conditions prevent continual reproduction, winter is spent as an egg, laid on a mustard-family plant. 254

A

B

C

D

E

F

A. Cotton-melon aphids.

G H

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

B. Cotton-melon aphids on primrose. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Pea aphids. WHITNEY CRANSHAW

D. Crapemyrtle aphids. DAVID SHETLAR

E. Oleander aphids.

I

DAVID CAPPAERT, BUGWOOD.ORG

F. Spotted hawthorn aphids. DAVID SHETLAR

G. Oak aphids.

J

DAVID SHETLAR

H. Asparagus aphids. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

I. Norway maple aphids. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

K

J. Overwintering eggs

of Norway maple aphid. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

K. Aphid eggs on pine needles. JIM KALISCH, UNIVERSITY OF NEBRASKA

L M

L. Colony of cabbage aphids. WHITNEY CRANSHAW

M. Cabbage aphids on

Brussels sprouts. WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

APHIDS APHIDS IN NORTH AMERICA THAT DO NOT COMMONLY ALTERNATE BETWEEN PRIMARY (WINTER) AND SECONDARY (SUMMER) HOST PLANTS SCIENTIFIC NAME

COMMON NAME

HOST

SPECIES THAT COMMONLY PRODUCE OVERWINTERING EGGS (HOLOCYCLIC LIFE CYCLE) Acyrthosiphon pisum

Pea aphid

Pea, alfalfa, clover, other legumes

Acyrthosiphum lactucae

Lettuce aphid

Lettuce

Aphis ceanothi

Ceanothus

Aphis hederae

Ivy aphid

English ivy

Aphis middletoni

Corn root aphid

Aster, cornflower

Aphis pomi

Apple aphid

Apple, pear, quince, hawthorn

Aphis nerii

Milkweed aphid

Oleander, milkweeds, vinca

Aphis sedi

Sedum

Aulacorthum solani

Foxglove aphid

Numerous hosts including foxglove, lettuce, potato, clover, bulbs

Brachycorynella asparagi

Asparagus aphid

Asparagus

Brevicoryne brassicae

Cabbage aphid

Brussels sprout, cabbage, other crucifers

Callaphis betulaecolens

Common birch aphid

Birch

Callaphis juglandis

Dusky-winged walnut aphid

Persian walnut

Callipterinella callipterus Chaitophorus populicola

European white birch Poplar leaf aphid

Poplar, cottonwood

Chaitophorus populifolii

Poplar, cottonwood

Chaitophorus viminalis

Small black and green willow aphid

Willow

Chromaphis juglandicola

Walnut aphid

Persian walnut

Cinara coloradensis

Black polished spruce aphid

Spruce

Cinara curvipes

Bowlegged fir aphid

Fir, Engelmann spruce

Cinara fornacula

Green spruce aphid

Spruce

Cinara laricis

Larch aphid

Larch

Cinara sabiniae

Rocky Mountain juniper aphid

Juniper

Cinara strobi

White pine aphid

Eastern white pine

Drepanosiphum platanoides

Sycamore aphid

Sycamore

Eucallipterus tiliae

Linden aphid

Linden

Hyadaphis tartaricae

Honeysuckle witches’-broom aphid

Tartarian honeysuckle

Macrosiphoniella sanborni

Chrysanthemum aphid

Chrysanthemum

Macrosiphum rosae

Rose aphid

Rose

Melanocallis caryaefoliae

Black pecan aphid

Hickory, pecan

Monellia caryella

Blackmargined aphid

Hickory

Monelliopsis pecanis

Yellow pecan aphid

Pecan

Myzocallis alhambra

Dusky-winged oak aphid

Oak

Myzocallis coryli

Filbert aphid

Filbert, hazelnut 256

SCIENTIFIC NAME

COMMON NAME

HOST

SPECIES THAT COMMONLY PRODUCE OVERWINTERING EGGS (HOLOCYCLIC LIFE CYCLE) Periphyllus lyropictus

Norway maple aphid

Norway maple

Periphyllus negundinis

Boxelder aphid

Boxelder maple

Phyllaphis fagi

Woolly beech aphid

Beech

Phorodon cannabis

Cannabis aphid

Cannabis

Meliarhizophagus fraxinifolii

Leafcurl ash aphid

Ash

Pterocomma smithiae

Black willow aphid

Willow, poplar

Sarucallis kahawaluokalani

Crapemyrtle aphid

Crape myrtle

Shivaphis celti

Asian woolly hackberry aphid

Hackberry

Shizaphis graminum

Greenbug

Bluegrass, corn, small grains

Sitobion avenae

English grain aphid

Corn, small grains

Tinocallis saltans

Siberian elm

Tinocallis ulmifolii

Elm leaf aphid

Elm, particularly American elm

Uroleucon ambrosiae

Brown ambrosia aphid

Aster family plants including lettuce, echinacea, rudbeckia, goldenrod

Uroleucon pseudambrosiae

Lettuce, sowthistle, endive

Uroleucon rudbeckiae

Goldenglow aphid

Goldenglow, larkspur, delphinium

Utamphorphora crataegi

Fourspotted hawthorn aphid

Hawthorn

SPECIES THAT RARELY OR NEVER PRODUCE OVERWINTERING EGGS (ANHOLOCYCLIC LIFE CYCLE) Aphis craccivora

Cowpea aphid

Legumes (cowpea, kidney bean, lima bean), asparagus, lettuce, carrot

Aulacorthum circumflexum

Crescentmarked lily aphid

Columbine, aster, lily, vinca, violet, cyclamen

Chaetosiphon fragaefolii

Strawberry aphid

Strawberry

Dysaphis tulipae

Tulip bulb aphid

Tulip, iris, gladiolus

Hyadaphis foeniculi

Fennel aphid

Carrot, parsley, fennel, dill, celery

Forda formicaria

1

Grass (roots)

Lipaphis pseudobrassicae

Turnip aphid

Many crucifers

Longistigma caryae1

Giant bark aphid

Oak, beech, nut trees

Myzus ascalonicus

Shallot aphid

Numerous, including alliums, dandelion, tulip, lettuce, strawberry

Rhopalosiphum maidis

Corn leaf aphid

Corn, small grains

Rhopalosiphum rufiabdomalis

Rice root aphid

Primarily roots of grains. Common on many plants in hydroponic production

Toxoptera aurantii

Black citrus aphid

Camellia, citrus, crape myrtle, ficus

Toxoptera citricidus

Brown citrus aphid

Citrus, ficus, camellia, gardenia

Tuberolachnus salignis

Giant willow aphid

Willow

Overwintering eggs may be produced in northern areas of range.

257

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

“WOOLLY APHIDS” Some aphids cover their body with long waxy threads, an effective deterrent to many natural enemies. Most of these “woolly” aphids are in the subfamily Pemphaginae1 and generally share life cycle similarities, including an affinity for developing on the roots or stems of secondary (summer) hosts. Differences occur in the habits of the sexual form and the production of only a single overwintering egg. Leaf curling is often produced by forms that colonize foliage. Several Eriosoma1 species are associated with elm as a winter host, with most alternating with other species as summer hosts where they feed on stems or roots. (Note: These species are also treated on pages 368 and 526.) Woolly pear aphid (E. pyricola), most common in the Northwest, alternates between elm foliage in spring and the twigs of pear. Summer generations of the woolly hawthorn aphid (E. crataegi) occur on branches and stems of hawthorn; rosette leaf distortions are produced on elm. Woolly elm aphid (E. americanum) develops on the roots of Amelanchier in the summer after moving from American elm, on which it tightly rolls leaves in the spring. Perhaps best known is the woolly apple aphid (E. lanigerum), which can build up dense colonies on suckers, branches, and, in warmer areas, roots of apple and crabapple. In much, if not most, of North America the woolly apple aphid does not have an alternate generation on elm. Woolly elm bark aphid (E. rileyi) is solely associated with elm, colonizing branches, and does not have a leaf curling generation. Leafcurl ash aphid (Meliarhizophagus fraxinifolii)1 develops on the expanding new growth of ash, particularly green ash, creating tightly rolled and thickened leaves sometimes referred to as “pseudo-galls.” Some associated distortion and twisting of twigs may also occur. The aphids are yellow-green with a brown head but are covered with white, waxy threads. Often they are found in curled ash leaves in dense mixtures of old cast skins and droplets of wax-coated honeydew. Winter is spent on the roots of ash. Prociphilus americanus1 produces injuries similar to leafcurl ash aphid in eastern North America during late spring but migrates to fir (Abies spp.), where summer generations occur on the roots. Prociphilus caryae alternates between serviceberry (Amelanchier), where it curls leaves, and the roots of white pine. Woolly alder aphid (P. tessellatus) develops on the branches of alder in summer; overwintering eggs are laid on silver maple and the subsequent spring generations may curl leaves of this host. Two common woolly aphids develop on beech. Colonies of beech blight aphid (Grylloprociphilus imbricator)1 develop on the foliage of beech in spring, later expanding Woolly alder to petioles and twigs. Woolly beech aphid (Phyllaphis fagi)2 is a European species aphid on maple. LACY L. HYCHE, AUBURN now widely distributed in North America. All stages occur on beech foliage, and the species UNIVERSITY, BUGWOOD.ORG is frequently abundant. Asian woolly hackberry aphid (Shivaphis celti)2 is a recently introduced species that has spread throughout much of the southern U.S. and is also found in California. It produces conspicuous colonies on hackberry leaves, with pale bluish wax surrounding the developing insects. Woolly aphids associated with conifers, known as adelgids, colonize needles, twigs, and trunks. Most that are associated with needles are in the genus Pineus.3  Hemiptera: Aphididae (Pemphiginae); 2 Hemiptera: Aphididae (Drepanosiphinae); 3 Hemiptera: Adelgidae

1

258

A

B

C

D

E

F

G

H

A. Leafcurl produced by woolly elm aphid. STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

B. Colony of woolly

elm aphids.

I

WHITNEY CRANSHAW

F. Woolly beech aphid. DAVID SHETLAR

G. Asian woolly

hackberry aphid. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Woolly apple aphid

H. Winged adult Asian woolly hackberry aphid.

WHITNEY CRANSHAW

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

colony on crabapple stem.

D. Damage produced by leafcurl ash aphid. WHITNEY CRANSHAW

E. Colony of leafcurl

ash aphid.

WHITNEY CRANSHAW

I. A Pineus species adelgid on pine needle. WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

MEALYBUGS ASSOCIATED PRIMARILY WITH FOLIAGE Note: Mealybugs associated primarily with twigs are treated on page 372. Species that develop primarily on roots are described on page 528.

Citrus Mealybug (Planoccoccus citri)1 hosts Many plants grown in greenhouses are susceptible, as are several common plants used in interiorscapes such as ficus and philodendron. Coleus, fuchsia, gardenia, apple, stone fruits (Prunus spp.), and rose are common hosts. Citrus mealybug is an important pest of citrus orchards, particularly grapefruit, where it tends to settle on the underside of fruit. Damage Citrus mealybug damages plants in several ways. Feeding can weaken the plant by removing sap, and the saliva introduced into plants causes vascular blockage, resulting in distortion to new growth and leaf drop. The wax-covered bodies of the mealybugs and the honeydew they excrete degrade plant appearance. Distribution Widespread in greenhouses and on indoor plants in the U.S. in extreme southern areas not normally susceptible to hard winter freezing. Appearance Generally oval and marked by having 17–18 pairs of short wax filaments along the side of the body and no tail filaments. An indistinct purplish stripe can often be observed along the back. Life History and Habits Eggs are produced by the adult females in a large egg sac (ovisac) which may contain up to 600 eggs. The eggs hatch after 7–10 days, and the young yellowish nymphs, known as crawlers, move about the plant seeking favorable sites for feeding. Terminal growth, cracks, and crotches are common areas where the crawlers settle. During development, females undergo two additional molts before becoming full grown. They maintain their legs throughout life but usually move little in later stages of development. However, they may move off plants and in greenhouses have been observed to lay eggs on benches, containers, and other nonplant surfaces. Off the plant, citrus mealybug may survive more than 2 weeks. The rarely observed males undergo an additional (fourth) development stage that is nonfeeding and occurs in a small cocoon of loose wax. Adult males are much smaller than the females, have wings, and do not feed. Females can lay eggs in the absence of males. A generation of citrus mealybug can be completed in about 1 month under optimal conditions indoors. Two to three generations are produced annually outdoors in Florida.

Longtailed Mealybug (Pseudococcus longispinus)1 hosts A wide variety of plants including begonia, citrus, dracaena, gardenia, ivy, impatiens, philodendron, tomato, coleus, poinsettia, fig, fuchsia, ferns, begonia, pyracantha, holly, yew, and rhododendron. Damage Longtailed mealybug feeds on the sap and in moderate numbers can induce leaf abscission. It also produces nuisance amounts of honeydew. Distribution Occurs outdoors in the southern states, as far north as Maryland. This mealybug is one of the most common and widely distributed insects associated with greenhouse and interiorscape plants. Appearance Oval, about ⅛ inch long, and covered with powdery wax. Longtailed mealybug lacks distinctive striping along the back but has numerous waxy filaments extending along the sides of the body. The presence of long threadlike tails, one pair of which may exceed the length of the body, is a distinguishing feature. 260

A. Citrus mealybug and associated honeydew. WHITNEY CRANSHAW

B. Citrus mealybug

A

infesting fruit.

B

JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Citrus mealybug

C D

producing egg sac. WHITNEY CRANSHAW

D. Male of the citrus

mealybug.

WHITNEY CRANSHAW

E. Citrus mealybug crawlers

and young nymphs. WHITNEY CRANSHAW

F. Longtailed mealybug. DAVID SHETLAR

G. Longtailed mealybugs

with egg sacs.

WHITNEY CRANSHAW

E

F

G

Life History and Habits Longtailed mealybug produces eggs that hatch almost immediately once outside the mother, essentially in the form of live birth. The young may remain under the mother for a few days and are released into a loose, snowy white mass of wax produced by the female that is conspicuous but much less developed than the ovisacs of some other species. The young feed on leaves and small branches, but females migrate to more protected sites when rearing young. Under optimal conditions, development may be completed in about 45 days, after which there is a fairly extended period during which eggs mature. Females produce young over a period of a month, but some 90% are typically laid in the first 10 days. Outdoors, typically two or three generations are completed annually. Males are produced and are required for successful reproduction. 261

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

MEALYBUGS ASSOCIATED PRIMARILY WITH FOLIAGE

Other Mealybugs Observed on Foliage Comstock mealybug (Pseudococcus comstocki) is found primarily in the northeastern quarter of the U.S., parts of southern Canada, California, and Washington. Historically it has been a pest primarily of pear and other fruits such as apple and peach. Its host range is broad, however, and includes (but is not limited to) privet, mulberry, maple, hibiscus, catalpa, buckeye, pine, and yew. Young nymphs usually feed on leaves, whereas older stages tend to aggregate on twigs, often around nodes and scars. Two generations are annually produced. Obscure mealybug (P. viburni) is an important pest of ornamentals with a host range of more than 50 plant genera. It can occur on the upper roots as well as the aboveground portion of plants. Citrophilus mealybug (P. calceolariae) is associated primarily with citrus, but it does occur on other fruit crops, including grape. Madeira mealybug (Phenacoccus madeirensis)1 and Mexican mealybug (P. gossypii) are two closely related species that are virtually identical in shape and form, with 3 rows of short, waxy tufts along the back and short terminal filaments. Eggs are laid in a large elongate egg sac that may be twice the length of the female. They are subtropical species with wide host range that can be found outdoors in the southern U.S. and are common greenhouse/interior plant pests throughout North America. Mexican mealybug is sometimes found on the upper roots as well as on leaves, stems, and flowers. Madeira mealybugs often overwhelm, even kill, hosts, while Mexican mealybugs are less damaging to hosts. Pink hibiscus mealybug (Maconellicoccus hirsutus)1 has attracted considerable attention and concern since its discovery in south Florida in 2002. Despite its name, it has a wide host range, including a variety of fruits and ornamentals and even certain vegetables. Adults are pinkish but covered with white wax. The eggs turn pinkish shortly after they are produced. As many as 15 generations can be produced annually. It has become a serious pest throughout south Florida and has been detected in southern Texas and California. Coconut mealybug (Nipaecoccus nipae)1 is found primarily on palms but sometimes feeds on other plants including sago palm, avocado, bird-of-paradise, dracaena, and orchids. Females are generally oval in form but have thick pyramids of wax on the back and 10-12 pairs of wax filaments along the sides. The related golden mealybug (N. aurilanatus) infests twigs of pines and araucarias in California. It has a dark purple body marked with a dorsal yellow stripe. Two related species are associated primarily with herbaceous, often annual, plants. Solenopsis mealybug (Phenacoccus solenopsis) feeds on a wide range of plants in the mallow and nightshade families, including hibiscus, cotton, and tomato. Adult females have an oval body thinly covered with wax with green stripes running parallel to a ridge in the center. Females produce a large ovisac. The solanum mealybug (P. solani) feeds on a variety of plants in the lily, aster, mallow, and nightshade families, often concentrated at the base of plants. It is covered with whitish wax, possesses only short waxy filaments along the sides, and does not have filament “tails.” It does not produce an ovisac.

262

A

B C D

E

F

G

A. Comstock mealybug. CLEMSON UNIVERSITY-USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

B. Obscure mealybug. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Citrophilus mealybug. USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

D. Madeira mealybug. ANNE W. GIDEON, BUGWOOD.ORG

E. Striped mealybug. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Mexican mealybug, mixed

life stages including male. DAVID SHETLAR

G. Solenopsis mealybug. USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

MEALYBUGS ASSOCIATED PRIMARILY WITH FOLIAGE, AND COCHINEAL SCALES Striped mealybug (Ferrisia virgata)1 is an introduced species found primarily in the eastern states. It has a gray body covered with white wax, except where two stripes on the abdomen distinctly mark this species. A pair of filaments on the tip of the abdomen, about half the length of the body, is also present. Dogwood, hawthorn, azalea, holly, magnolia, apple, and mulberry are among the hosts. Two generations are produced, with winter spent as a nymph. Gill’s mealybug (Ferrisia gilli) is a species recently described that is present in California pistachio production. It is also found on several deciduous ornamentals, grapes, persimmons, and Prunus. Miscanthus mealybug (Miscanthiococcus miscanthi)1 develops at the base of the leaf sheaths of Miscanthus, producing dwarfing and poor growth. Roots are also commonly colonized. Three generations are produced per year in the central U.S., with winter spent as a fertilized adult female. Rhodesgrass mealybug (Antonia graminis)1 is a turfgrass-infesting species presently established in many areas of the southern U.S. Rhodesgrass is the primary host plant, but other warm season grasses may also be infested. Colonies are often concentrated at the base of the plants. Adults are characterized by a very long slender thread at the end of the abdomen that protrudes from the massed mealybugs. Large colonies may excrete considerable amounts of honeydew that is attractive to ants and wasps. A closely related species is noxious bamboo mealybug (A. pretiosa),1 which develops at the nodes of Bambusca and Phyllostachys species of bamboo. Two species of mealybugs are associated with buffalograss, Tridiscus sporoboli (buffalograss mealybug) and a Trionymus species. These are small mealybugs that are easily overlooked and can usually be found inside or near leaf sheaths. Symptoms during heavy infestations are similar to those produced by drought stress, and plants often have a reddish-purple discoloration. 1

Hemiptera: Pseudococcidae

COCHINEAL SCALES Cochineal scales (Dactylopius spp.)1 develop on prickly pear and sometimes other cacti. They produce large, conspicuous cottony masses of wax that cover the mature female and eggs. First-stage nymphs (crawlers) feed for about 3 weeks before settling, after which they remain immobile. Males develop in a small cocoon during their later stages. Multiple overlapping generations are produced in warmer areas of the southwestern states and Florida, where D. opuntiae is present. Two generations are normal for D. confusus in the Rocky Mountain States. Cochineal scales have long been prized as a source of natural red dye, a color due to high levels of carminic acid in their blood. The species D. coccus is the cochineal scale usually used commercially for this purpose and is less covered with wax than D. confusus. Dactylopius coccus has been introduced into the U.S. and is now present in most southwestern states. 1

 Hemiptera: Dactylopiidae

264

A C

B D

A. Crawler stages of miscanthus mealybug. DAVID SHETLAR

B. An Antonia

species of mealybug on bamboo. DAVID SHETLAR

C. Rhodesgrass

mealybug.

DAVID SHETLAR

D. Mealybugs

on buffalograss. JIM KALISCH, UNIVERSITY OF NEBRASKA

E

F

E. Cochineal scales

on prickly pear cactus. WHITNEY CRANSHAW

F. Cochineal scales

with crawlers.

WHITNEY CRANSHAW

G. Dark red blood

(carmine) of cochineal scale. WHITNEY CRANSHAW

G

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

SOFT SCALES ASSOCIATED PRIMARILY WITH FOLIAGE Soft scales suck fluids from the phloem of plants and most excrete conspicuous amounts of honeydew. Unlike the armored scales, nymphal stages of soft scales retain some mobility during development and they migrate between foliage and twigs. Most soft scales ultimately settle on twigs in the adult stage and are discussed in chapter 4, but a few are most commonly observed on leaves.

Brown Soft Scale (Coccus hesperidum)1 hosts Ficus, citrus, Schefflera, and English ivy are among the most common hosts; however, brown soft scale has an extremely wide range of potential hosts. Damage Heavy infestations of twigs and leaves can cause wilting, premature leaf drop, and dieback. A more commonly observed problem is the abundant amount of honeydew produced by this insect, which is often later associated with sooty molds. Distribution Soft brown scale is found throughout North America and the most common scale insect associated with indoor-grown houseplants. Cold winter temperatures restrict it as a year-round species on outdoor plants to southern areas where freezing temperatures are rare. Appearance Full-grown female scales (males are rare) are light brown, oval, and generally flattened in shape. Younger scales are yellowish brown with splotchy dark areas along the middle and sides. Life History and Habits Eggs hatch over an extended period, underneath the bodies of the females. After crawling about the plant, the nymphs settle, begin to feed, and molt a couple of times. Upon reaching adulthood, the female exoskeleton hardens into a shell-like cover. Late-stage nymphs and adults remain immobile for the rest of their lives. Generations are produced continually and overlap. A single generation is typically completed in 2–3 months.

Other Soft Scales Observed on Foliage Citricola scale (Coccus pseudomagnoliarum) is similar in appearance to brown soft scale but gets slightly larger and is grayish. Citrus, elm, hackberry, pomegranate, and walnut are common hosts in California. One generation is produced annually. Green scale (C. viridis) is elongate oval in shape and a distinctive light green color when alive. It can cover foliage and small stems. It is established in the southern half of Florida but can survive on greenhouse plants and houseplants. It commonly infests citrus, gardenia, Schefflera, Cuban laurel, and several other woody houseplants. Cottony maple leaf scale (Pulvinaria acericola)1 develops on maple, dogwood, and holly in the eastern U.S. and southern Canada. Its life history differs a bit from that of cottony maple scale (page 382) in that mature females migrate back to leaves in spring, where they subsequently produce cottony egg sacs. Cottony camellia scale (P. floccifera), sometimes known as “cottony taxus scale,” has a similar life history. It produces a long, narrow egg sac, and eggs hatch over an extended period of about 6 weeks. Holly, camellia, jasmine, and yew are among the common hosts.

266

A

B

C D

E

A. Brown soft scales on bay leaf. WHITNEY CRANSHAW

F

B. Brown soft scales and associated honeydew. WHITNEY CRANSHAW

C. Honeydew produced by

G brown soft scale collecting on lower leaf.

WHITNEY CRANSHAW

D. Green scale. DAVID SHETLAR

H

E. Citricola scale. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

F. Sooty mold growing on honeydew excreted by green scale. DAVID SHETLAR

G. Cottony maple leaf scale. DAVID SHETLAR

H. Cottony maple leaf

scale stage on twigs. DAVID SHETLAR

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

SOFT SCALES ASSOCIATED PRIMARILY WITH FOLIAGE Pyriform scale (Protopulvinaria pyriformis)1 is a fairly large, irregularly pear-shaped scale that settles on the underside of the leaves of many tropical and semitropical ornamental plants. Adults are light reddish brown with a darker margin. Females lay the eggs within a flattened ovisac that surrounds the body. Turfgrass scale (Lecanopsis formicarum)1 is a potential pest of Kentucky bluegrass, red fescue, and some other cool-season grasses. It is most visible in late spring and early summer when females produce a cottony egg sac at the base of stems and leaves. Turfgrass scale is a European species found in eastern Canada and upper New York. Early-stage nymphs (crawlers) are reddish, later stages more yellow. Tessellated scale (Eucalymnatus tessellatus)1 is a tropical species that can occur in greenhouses and has established outdoors in parts of Florida, where it is associated mostly with palms, mango, and crepe-jasmine. Florida wax scale (Ceroplastes floridensis)1 can be common on citrus and hollies in the southeastern states. Stages that settle on leaves often line up along main veins. Indian wax scale (C. ceriferus) develops on many plants but is particularly common on holly and can produce large amounts of honeydew. These species, along with other wax scales (Ceroplastes spp.), are also often found on twigs. Croton scale (Phalacrococcus howertoni) is a recently (2008) established scale in southern Florida that has shown great damage potential. Croton, several figs, guava, gumbo-limbo, and mango are among its hosts. 1

Hemiptera: Coccidae

top left: Florida wax scale, flipped to expose eggs. CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SERVICE, BUGWOOD.ORG

bottom left: Indian wax scale.

DAVID SHETLAR

Sooty mold associated with Indian wax scale infestation of holly. DAVID SHETLAR

268

A

B

C D E F

A. Pyriform scale.

D. Croton scale.

DAVID SHETLAR

DOUG CALDWELL, UNIVERSITY OF FLORIDA

B. Turfgrass scale. DAVID SHETLAR

C. Tesselated scale. DAVID SHETLAR

E. Florida wax scale. CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SERVICE, BUGWOOD.ORG

F. Indian wax scale. DAVID SHETLAR

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

ARMORED SCALES OBSERVED PRIMARILY ON FOLIAGE Armored scales suck fluids from the mesophyll cells of plants and, unlike soft scales and mealybugs, do not excrete honeydew. Armored scales also differ by losing their legs after the first molt and are only active during the firstinstar “crawler” stage. Most armored scales occur on twigs and branches and are discussed in chapters 4 and 5, but a few are most commonly observed on needles or leaves of evergreen deciduous trees and shrubs.

Pine Needle Scale (Chionaspis pinifoliae)1 hosts A wide variety of conifers, particularly certain pines and spruce. Douglas-fir and hemlock are infrequent hosts. Damage Pine needle scale feeds on needles, often producing some localized discoloration around the feeding site. In high numbers, it can produce premature needle shed and some dieback of branches. Distribution Generally distributed throughout North America but is most common in the northern half of the U.S. and southern Canada. Appearance Adult females are almost pure white, elongated, and armored. They are slender and slightly yellow at the front end, widening at the rear. Males, when present, have a smaller, narrower scale cover. Crawler stages are light purple. Life History and Habits The life history varies in different parts of North America. In most areas, the primary overwintering stage is eggs, underneath the mother scale. In some areas, particularly with mild winters, some females may survive and produce eggs throughout winter and into early spring. Eggs usually hatch in midspring, often coincident with the peak bloom of common lilac. Crawlers settle within a few days of hatch and subsequently remain in place for the rest of their lives. In much of the eastern U.S. a second generation occurs, with eggs hatching in early summer and the adults maturing in early fall. (Small, partial third generations have sometimes been observed.) Single-generation strains typically predominate in the west. Also, males are common in eastern areas but largely absent in western populations.

Other Armored Scales Observed on Foliage Pineleaf scale (Chionaspis heterophyllae)1 is closely related to pine needle scale, nearly identical in form, and associated with pine in eastern North America. Black pineleaf scale (Nuculaspis californica)1 can be found on the needles of pines, firs, and Douglas-fir, occasionally producing outbreaks in pines under droughty conditions. Non-native pines, such as Scotch and Austrian pine, are particularly susceptible. One generation is produced per season in the north; two in southern states.

270

A B

C D

E

F

G

H

I

A. Pine needle scale. DAVID SHETLAR

B. Pine needle scale with eggs. DAVID SHETLAR

C. Infestation of

pine needle scale. DAVID SHETLAR

J

D. Pine needle scale, adult female exposed from under cover. DAVID SHETLAR

E. Pine needle scale

exposed while producing eggs. WHITNEY CRANSHAW

F. Pine needle scale crawlers. DAVID SHETLAR

G. Pineleaf scale. J. A. DAVIDSON, UNIVERSITY OF MARYLAND, BUGWOOD. ORG

H. Pine needle scale nymphs. WHITNEY CRANSHAW

I. Recently settled

nymphs of black pineleaf scale.

DONALD OWEN, CALIFORNIA DEPARTMENT OF FORESTRY AND FIRE PROTECTION, BUGWOOD.ORG

J. Black pineleaf

scale.

WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

ARMORED SCALES OBSERVED PRIMARILY ON FOLIAGE Juniper scale (Carulaspis juniperi)1 has females that are round but commonly distorted by the rough surface of juniper leaves. The tiny males are elongate drop-shaped. They are bright white with yellow exuviae (central on the female and on one end on the male), but can become gray over time. Heavy infestations can completely cover juniper foliage, causing severe dieback, even whole plant death. Hemlock scale (Abgrallaspis ithacae)1 females form small, circular to oval-shaped, gray shells on the needles of hemlock, pine, fir, and Douglas-fir. It is most common in the native range of eastern hemlock. It produces two generations per year with second-stage nymphs overwintering. Elongate hemlock scale (Fiorinia externa)1 can often be found alongside the hemlock scale, but the cover of F. externa is parallel-sided and three times the length of the hemlock scale. This is a non-native species that caused severe dieback of hemlock until parasitic wasps and a lady beetle were introduced that effectively achieved biological control. Tea scale (Fiorinia theae) is an imported pest that commonly attacks holly and camellias. The female covers are brown to black and spear-shaped, while males appear as clusters of tiny white exclamation marks. Heavy infestations cause yellowing of leaves and early drop. Oleander scale (Aspidiotus nerii)1 feeds on plants in more than 100 families, but oleander is a particularly common host in the U.S. Mature female scales are circular and range from white to light brown in color. Males, if they occur, are only about half the size of females, but many parthenogenetic strains (absent males) are known. Increasing evidence suggests that A. nerii is a species complex, with differences in host range and reproduction. Cryptomeria scale (A. cryptomeriae) is a common insect on true firs (Abies spp.) and hemlock in the eastern states. Florida red scale (Chrysomphalus aonidum)1 is a common pest of evergreen holly, especially in southern states. It can also infest many other plants, especially citrus, where it can cause leaf drop and early fruit drop. The scale is fairly small, round, and dark reddish brown in color. Euonymus scale (Unaspis euonymi)1 is a common species on evergreen shrub types of euonymus and can occur on a few other shrubs. Females are brown and somewhat oystershell-shaped and males are fuzzy white and elongated. Females develop primarily on twigs, but some females and the more conspicuous white-colored males occur on leaves. Sweetgum scale (Diaspidiotus liquidambaris)1 is usually first noticed when yellow, red, or dark green spots appear on sweetgum leaves. This scale has a leaf-feeding phase in which first instars settle on the undersurface of leaves. Their feeding activity causes the leaf to swell around the scale, which then develops in a pitlike cavity. Upon maturing, the secondstage scale moves back to the stems to finish development. This scale has two generations per year with unmated females and males overwintering on stems and branches.

Sweetgum scales on sycamore leaf. DAVID SHETLAR

A

B

A. Juniper scales. DAVID SHETLAR

B. Hemlock scale. PENNSYLVANIA DEPARTMENT OF CONSERVATION AND NATURAL RESOURCES–FORESTRY, BUGWOOD.ORG

C. Elongate hemlock scale. ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

D. Oleander scale. CHARLES OLSEN, USDA APHIS PPQ, BUGWOOD.ORG

E. Florida red scale.

C

LORRAINE GRANEY, BARTLETT TREE CARE, BUGWOOD.ORG

F. Tea scale.

D

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SERVICE, BUGWOOD.ORG

E

G. Cryptomeria scale. LORRAINE GRANEY, BARTLETT TREE CARE, BUGWOOD.ORG

H. Euonymus scale. DAVID SHETLAR

I. Sweetgum scale

close-up.

DAVID SHETLAR

J. Euonymus scale leaf

F G

injury symptoms. DAVID SHETLAR

H

I

J

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

ARMORED SCALES OBSERVED PRIMARILY ON FOLIAGE Cactus scale (Diaspis echinocacti) occurs on a wide variety of cacti and is the most common armored scale on these plants. Under suitable temperature conditions, a generation can be completed within a month, with adult females laying eggs over a 1–2-month period. Boisduval scale (Diaspis boisduvalii) is a general feeder of many tropical plants but primarily a pest of orchids, yucca, and palms. There are several Lepidosaphes species associated primarily with foliage. Purple scale (L. beckii) is very similar in appearance to oystershell scale but associated with citrus in parts of California and Florida. Three generations per year commonly occur in Florida. Camellia scale (L. camelliae), widely distributed in the eastern half of the U.S., is associated with camellia, holly (particularly Burford holly), privet, Cleyera, Ternstroemia, and Rhaphiolepsis. As many as 4–5 generations are reported in Georgia. Winged euonymus scale (L. yanangicola) develops damaging populations on winged euonymus in some mid-Atlantic and midwestern states. It is commonly mistaken as small oystershell scales. Maskell scale (L. pallida) develops on Cryptomeria and Taxus. It is part of a species complex that includes pine oystershell scale (L. pini) on Pinus thunbergii and P. densiflora, and umbrella pine scale (L. sciadopitysi) on Sciadopitys. Two generations are commonly produced by Maskell scale, with crawlers appearing in June and August. Fern scale (Pinnaspis aspidistrae) is pear- to oystershell-shaped and usually light brown in color. This is a tropical species that can occur on ferns grown inside. The scales settle on leaves, stems, and bark. Aulacaspis yasumatsui,1 known variously as the “Asian cycad scale,” “cycad aulacaspis scale,” or “sago scale,” is an insect first discovered in the U.S. in 1997 that has proved devastating to king and queen sago cycads. Large populations build up quickly on foliage, with generation times of about 1 month, and heavily infested plants can be killed. Control is complicated by the occurrence of many individual scales on belowground parts of the plant. Originally found in Florida, it is now also known from Texas. Natural enemies of this insect were collected from areas where it top: Cactus scale. DAVID SHETLAR is native (Southeast Asia), and efforts to establish them appear to have above: Asian cycad scale. DAVID SHETLAR successfully improved biological control of this insect. Pinyon needle scale (Matsucoccus acalyptus)2 develops on pinyon in the southwestern U.S., occasionally producing outbreaks that cause foliage yellowing and premature needle drop. The most conspicuous stage of this insect are the small, black, second-instar nymphs, known as the “bean stage,” attached to needles through winter into early spring. Later stages migrate to trunks in spring and lay eggs. A life cycle that also involves alternation between leaves and stems occurs with sycamore scale (Stomacoccus platani).1 Sycamore scale is present in the southwestern U.S. and can produce 3–5 generations in a year. 1

Hemiptera: Diaspididae; 2 Hemiptera: Margarodidae

274

B

A C

D E

F

G

A. Maskells scale. LORRAINE GRANEY, BARTLETT TREE CARE, BUGWOOD.ORG

B. Pine oystershell scale. LORRAINE GRANEY, BARTLETT TREE CARE, BUGWOOD.ORG

C. Camellia scale. ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

D. Fern scale. J. A. DAVIDSON, UNIVERSITY OF MARYLAND, BUGWOOD.ORG

E. Bermudagrass scale. DAVID SHETLAR

F. Heavy infestation of Asian cycad scale. DOUG CALDWELL, UNIVERSITY OF FLORIDA

G. Pinyon needle scale. WHITNEY CRANSHAW

H. Sycamore scale crawler. LORRAINE GRANEY, BARTLETT TREE CARE, BUGWOOD.ORG

H

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

PSYLLIDS Psyllids are small insects, about 1⁄10–3⁄16 inch in length when full grown. Adults somewhat resemble miniature cicadas and are often referred to as jumping plant lice because of their ability to jump. Nymphs are flattened and often scalelike in appearance, found attached usually to the underside of leaves or within leaf pockets or folds. Taxonomically, psyllids are considered a superfamily (Psylloidea) comprising three families: Psyllidae, Triozidae, and Calophyidae. Psyllids tend to be quite specific in their hosts, usually restricting their feeding to a single genus or family of plants, and some types of plants (e.g., willows, sumac) support many psyllid species. The overwhelming majority of the 300-plus North American species develop on dicots. Many psyllid species cause little, if any, plant damage and have habits that rarely attract attention. Others can cause significant plant injury, not only from removal of plant fluids during feeding, but also through effects induced by their introduced saliva. Distortions of leaf growth and production of pits or swellings on leaves are among the symptoms caused by some psyllids. A few have saliva that is systemically toxic to the plant and can produce a wide range of disorders, and some psyllids are important as vectors of phytoplasmas that can cause serious plant diseases. Many psyllids excrete materials as they feed that are quite distinctive and can be useful in diagnosis. Many excrete honeydew, which may crystalize over and cover the developing nymphs, but others excrete distinctive waxy threads or wax-covered pellets. Note: Many psyllids produce leaf galls in the form of pits or lumps on leaves. These are discussed later in this chapter on page 326.

Potato/Tomato Psyllid (Bactericera cockerelli)1 hosts Many solanaceous plants can host potato/tomato psyllid, including eggplant, pepper, tomatillo, Lycium spp., and some other nightshade family plants. Only tomato and potato appear to sustain significant injury as a result of feeding by the insect. Damage Saliva injected during feeding causes various disruptions of plant growth, collectively described as psyllid yellows. Slowed plant growth, leaf curling, and color changes are common results. Effects on potato tubers include reduced size, premature sprouting, and rough skin. Tomatoes damaged by this species produce small fruits that are soft and of poor quality. In some areas, particularly in Texas, southern California, and much of Mexico, the potato psyllid is also important as a vector of the phytoplasma, Candidatus Liberibacter solanacearum. This can produce a disease known as zebra chip that causes dark streaking in potato tubers, particularly after they are cooked. This pathogen can also damage tomato and pepper. Distribution Texas, southern California, and areas of northern Mexico are most commonly infested during cool-season months. Dispersal through the High Plains and Rocky Mountain regions occurs during late spring and early summer. Appearance Mature adults are generally dark gray or black with distinct white bands and markings. These markings take a few days to develop, so newly emerged adults are pale-colored. Nymphs are flattened and have a series of minute waxy projections surrounding the body. Young nymphs are pale brown or tan. Older nymphs become increasingly greenish and develop noticeable wing pads. Eggs are minute but laid on a characteristic small stalk. Life History and Habits Potato/tomato psyllid is a migratory insect wintering in the extreme southwestern U.S. and Mexico. It annually migrates northward in late spring, when temperatures begin to get hot in the overwintering breeding areas. Females lay small yellow-orange eggs in small groups, usually on the underside 276

A. Tomato/potato psyllid adult. WHITNEY CRANSHAW

B. Tomato/potato

psyllid nymphs.

A

WHITNEY CRANSHAW

B

C. Tomato/potato

psyllid adult laying eggs. WHITNEY CRANSHAW

D. Mixed stages of

tomato/potato psyllid adult on tomato leaf. WHITNEY CRANSHAW

E. “Psyllid sugar”

excrement produced by tomato/potato psyllid adult. WHITNEY CRANSHAW

F. “Psyllid yellows”

C D

foliar color change of potato produced by tomato/potato psyllid feeding. WHITNEY CRANSHAW

G. Premature tuber

sprouting associated with tomato/potato psyllid injury. WHITNEY CRANSHAW

H. Dull fruit color

E

symptomatic of tomato injury by tomato/potato psyllid.

F

WHITNEY CRANSHAW

G H of leaves. The nymphs are flattened and somewhat scalelike. Nymphs rarely move and tend to concentrate on the underside of leaves in more shaded areas of the plant. After 3–4 weeks the adults emerge and repeat the cycle. During a season, 3–4 generations may be completed in a region. A reverse migration to southern areas is assumed to occur in early fall. Potato/tomato psyllid may breed continuously in greenhouses and has developed as a pest of greenhouse tomatoes. 277

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

PSYLLIDS

Pear Psylla (Cacopsylla pyricola)2 hosts Restricted to fruit-producing pear. Species of ornamental pear do not appear to be susceptible to this insect. Damage Pear psylla feeds on the leaves of pear trees, excreting large amounts of honeydew that cover leaves and fruit and allow growth of sooty molds. High numbers of psyllids on trees can reduce plant vigor, cause necrotic spotting of leaves, and even induce a condition known as psylla shock, resulting in leaf drop and suppressed growth from which it may take a plant several years to recover. In some areas pear psylla is also important in the spread of the phytoplasma (Candidatus  Phytoplasma pyri) that produces Eggs of pear pear decline disease. psylla on twigs. KEN GRAY COLLECTION, Distribution Of European origin, pear psylla can be found wherever pear is OREGON STATE UNIVERSITY grown. It is particularly damaging in the Pacific States and in the Northeast. Appearance Adults are dark reddish brown with clear wings. Young nymphs are pale yellowish but develop dark markings and wing pads as they get older. Nymphs are often covered with droplets of honeydew. Life History and Habits Pear psylla adults overwinter in protected areas (under bark, plant debris on soil, or other cover) in the vicinity of previously infested trees. It becomes active in late winter or early spring and moves to pear trees, laying yellow-orange eggs as pear buds begin to swell. The emerging nymphs then move to feed on the tender new growth. As they feed, young pear psylla nymphs become covered with the honeydew droplets they excrete. During the final nymphal stage, conspicuous wing pads develop and the nymphs leave the honeydew droplet, subsequently molting to the adult stage. Later generations lay eggs on the new leaves, often concentrating on sucker sprouts late in the season. Two to three generations are normally produced in a season. At the end of the year, dark-colored winter adult forms move to shelter.

Other Psyllids Perhaps the most important Cacopsylla species, aside from pear psylla, is boxwood psyllid (C. buxi).1 Common in the eastern and northwestern states, this species can produce conspicuous leaf-cupping distortion to American boxwood. Nymphs cover themselves with long threads of wax as they feed on the newly developing leaves in spring. One generation occurs per year, with adults laying overwintering eggs around bud scales in early summer. Adults occasionally settle on skin of humans when infested plants are disturbed; they can produce a bite that may be felt as a small prick but is not painful. Approximately 60 Cacopsylla species occur in North America, about half of which occur on willow. Among the others that may occasionally be noticed by gardeners include apple sucker psyllid (C. mali), which feeds primarily on sprouts of fruit trees; boxelder psyllid (C. negundinis), which may produce modest leaf distortion and noticeable honeydew; and sumac psyllid (C. triozimima), which can be abundant on Rhus. Cacopsylla tobirae is a non-native species associated with Japanese pittosporum (Pittosporum tobira). Feeding can induce a tight curling of the new growth and they excrete honeydew and produce conspicuous threads of wax. This psyllid has recently been found in California and its occurrence reported in North Carolina. 278

A

B

C D

A. Pear psylla adult. WHITNEY CRANSHAW

B. Pear psylla nymphs

in honeydew droplets. WHITNEY CRANSHAW

C. Upper leaf symptom

produced by pear psylla feeding. WHITNEY CRANSHAW

D. Boxwood psyllid

nymphs and associated wax thread excrement. JOHN CAPINERA, UNIVERSITY OF FLORIDA

E. Boxwood psyllid

adult.

E

F

DAVID SHETLAR

F. Boxelder psyllids. WHITNEY CRANSHAW

G. Leaf cupping

produced in response to boxwood psyllid feeding. WHITNEY CRANSHAW

H. Sumac psyllid adults. WHITNEY CRANSHAW

I. Overwintering nymphs of sumac psyllid. WHITNEY CRANSHAW

G H

I

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

PSYLLIDS Asian citrus psyllid, Diaphorina citri,2 is an insect recently introduced into North America that has high potential to devastate the citrus industry. The insects feed on the stems and young leaves, and the feeding injuries result in some cupping distortion of new growth and dieback of new shoots. The importance of Asian citrus psyllid can be enormously increased, however, by its ability to vector the pathogen that produces the huanglongbing (HLB) disease, also known as citrus greening. Since its first detection in southeast Florida in 1998, Asian citrus psyllid has spread to infest all of Florida and some areas of all states where citrus is grown. The pathogen that produces citrus greening is a type of bacterium (phytoplasma), Candidatus Liberibacter asiaticus. It is introduced into plants during feeding by Asian citrus psyllids that previously fed on an infected tree. Once introduced, the bacteria grow in the phloem of the trees and produces a progressive, irreversible disease that is usually fatal in about 5 years. Early symptoms include a blotchiness of leaves, followed by increasing foliage yellowing. Fruit production declines and individual fruits decline in quality, become misshapen, smaller, and show incomplete ripening. Citrus greening is now found throughout the citrus-producing areas of Florida and was more recently discovered in Los Angeles. The disease is also present in Mexico and progressing northward with the movement of infected psyllids. The Asian citrus psyllid is relatively large (ca. 1⁄6 inch), mottled brown, and perhaps most recognizable by the way the adult insects position themselves on leaves, tipped at a 45° angle. Eggs are laid on the tips of shoots and the nymphs feed on young shoots and leaves. As many as 8–10 generations can be produced, although development slows during winter, as nymphs can develop only on newly produced growth. Several non-native psyllids associated with eucalyptus have been accidentally introduced and become established in parts of North America, particularly California. Redgum lerp psyllid (Glycaspis brimblecomei)2 spread quickly after it became established in California in the late 1990s and was later discovered to be established in Florida. In addition to causing feeding injuries and nuisance problems with excreted honeydew, it forms a conspicuous, conical wax cap (lerp) over the nymphs. Eucalyptus globulus is most commonly infested. Bluegum psyllid (Ctenarytaina eucalptyi)2 is also a recent introduction and has developed into an important pest of Eucalyptus pulverulenta grown to provide foliage for flower arrangements. Blastopsylla occidentalis1 occurs on eucalyptus in Florida. Lemongum psyllid (Cryptoneossa triangula)2 and spotted gum psyllid (Eucalyptolyma maidenii)2 are minor pests on lemon-scented gum (Eucalyptus citriodora) and spotted gum (Eucalyptus maculata) in California. Acacia psyllid (Acizzia uncatoides)2 is a common species in California, associated with acacia and silk tree, sometimes occurring in nuisance or even damaging numbers. The nymphs of rudbeckia leafspot psyllid (Bactericera antennata)2 produce a purplish blotch on the leaves of black-eyed Susan and other Rudbeckia species in the Midwest. More recently it has also been reported to feed on hibiscus. Adults have pink to purple bodies with clear wings, and adults seem not to cause noticeable damage. Cottony ash psyllid (Psyllopsis discrepans)2 can cause severe leaf distortion of black and Manchurian ash. It is a European species that appears to have spread widely across Canada since its North American detection in Nova Scotia and is presently most damaging in the Plains provinces and Dakotas. A related species, P. fraxinicola, has recently become established in Oregon, where it develops on European and narrow-leaved ash. 1

Hemiptera: Triozidae; 2 Hemiptera: Psyllidae; 3 Hemiptera: Calophyidae

280

A

B

C D

E

F A. Adult citrus psyllid. DAVID HALL, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

B. Life stages of the Asian citrus psyllid. DAVID HALL, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

C. Asian citrus psyllids

H I

G D. Leaf yellowing and irregular fruit ripening associated with Asian citrus psyllid. JEFFREY W. LOTZ, FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES, BUGWOOD.ORG

E. Bluegum psyllid colony. ROBIN ROSETTA, OREGON STATE UNIVERSITY

infesting terminal growth.

F. Redgum lerp psyllid.

JEFFREY W. LOTZ, FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES, BUGWOOD.ORG

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

J

G. Acacia psyllids. DAVID SHETLAR

H. Leaf spotting produced

by rudbeckia psyllid. DAVID SHETLAR

I. Rudbeckia psyllid adults. DAVID SHETLAR

J. Rudbeckia psyllid nymph. DAVID SHETLAR

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

LEAFHOPPERS Leafhoppers1 are small insects, typically about ⅛–3⁄16 inch in length, elongate and somewhat wedge-shaped, and tapering at the end. Eggs are inserted as small groups in plant tissues, usually in leaf veins or small twigs. The nymphs are active insects, usually moving readily when disturbed, often with a side-to-side (crablike) walk. Adults are winged and fly readily, leaping from plants with their enlarged hind legs. More than 2,500 species of leafhoppers are found in North America, and some may be associated with almost any plant except those with thick, waxy foliage. All suck plant fluids with stylet mouthparts from leaves and, less commonly, succulent stems. Most species feed on the phloem of plants, removing only modest amounts of sap and excreting some honeydew. Other leafhoppers restrict their feeding to the parenchyma cells of the leaf mesophyll layer, producing white flecking wounds. These insects often excrete dark spots in the manner characteristic of other mesophyll-feeding insects, such as lace bugs and some thrips. Some members of the genus Empoasca can injure the vascular system of plants, producing a condition known as hopperburn. One group of leafhoppers known as the “sharpshooters” feed on the xylem fluids; they tend to be more elongated than other leafhoppers, with an elongated head. They get their name from the habit of some species of flicking small droplets during excretion, which may be detectable as fine spray. Some leafhoppers are important because of their ability to transmit plant pathogens that cause plant diseases. These include viruses (curly top), phytoplasmas (aster yellows, ash yellows, elm phloem necrosis), and the xylemlimited bacteria (bacterial leaf scorch, Pierce’s disease of grape).

Potato Leafhopper (Empoasca fabae)1 hosts A wide variety of plants, particularly legumes such as bean and alfalfa. Potato, raspberry, wisteria, and several trees, including maple, birch, and apple, are common hosts. Damage Destruction of cells during feeding and injection of saliva toxic to plants disrupt the phloem and sap flow of plants. Photosynthesis is reduced and foliage discoloration is common, typically a yellowing. Symptoms are usually first evident as leaf tip wilting that progresses backward as tissues die, resulting in a condition known as hopperburn. Severe leaf injury and even premature plant death are common on potato; more subtle leaf discoloration and curling are more characteristic on bean. On trees, reductions in shoot elongation result in stunting and close-spaced leaves Distribution Potato leafhopper is restricted to eastern North America, only infrequently being found as far west as Wyoming and Colorado. Appearance Pale green, about ⅛ inch, elongate, and gradually tapering to the hind end. Some pale spotting behind the head may be observed on close observation. The nymphs are lighter colored and highly active. They are found on leaf undersides and readily move sideways when disturbed. Life History and Habits Winter is spent in areas around the Gulf Coast, where potato leafhoppers feed in alfalfa and various weeds. A northward migration occurs annually, and often suddenly, in May or early June. Alfalfa and bean are often early season hosts, with potato increasingly favored later in the summer. Potato leafhopper may breed year-round in southern parts of its range but dies out in the north during winter. Females insert eggs into veins on the underside of the leaf. The young nymphs are pale green and gradually darken with age, molting four times over the course of 2–3 weeks before reaching the adult form. Three to five generations per year are typically produced in the midwestern states. This pest can suddenly appear in trees and shrubs following the harvesting of alfalfa, a favored host plant. 282

B

C

A

D

F

G

E

H I

A. Recently emerged adult

leafhopper next to nymphal skin. WHITNEY CRANSHAW

B. Sharpshooter leafhopper

excreting watery droplet. WHITNEY CRANSHAW

C. Leaf spotting (stippling) produced

by leafhopper that feeds on mesophyll. WHITNEY CRANSHAW

D. Potato leafhopper adult. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Potato leafhopper on wisteria. DAVID SHETLAR

F. Potato leafhopper nymph. DAVID SHETLAR

G. Leaf symptom associated with

hopperburn injury by potato leafhopper. JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Potato field killed prematurely

by potato leafhopper.

TED RADCLIFFE, UNIVERSITY OF MINNESOTA

I. Hopperburn injury to maple. DAVID SHETLAR

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

LEAFHOPPERS

Related Species Several other less commonly damaging species of Empoasca leafhoppers, sometimes described as garden leafhoppers, occur throughout North America. All are similar in general appearance—small green leafhoppers—to potato leafhopper and can be separated only by experts. Hopperburn-type symptoms caused by E. recurvata have been observed on winter squash in Colorado. Southern garden leafhopper (E. solana) apparently may also produce mild hopperburn symptoms on potato, bean, and lettuce in southern states. Other Empoasca species are not phloem feeders, however, and feed primarily on the mesophyll, producing white flecking (stippling) injuries to foliage. Western potato leafhopper (E. abrupta) and intermountain leafhopper (E. filamenta) are two western species that apparently produce white flecking injuries to potato but do not induce hopperburn. White flecking of foliage is produced on apple, hawthorn, pear, and some stone fruits by apple leafhopper (E. maligna).

Rose Leafhopper (Edwardsiana rosae)1 hosts Rosa species and Rubus species are overwintering hosts. Dogwood, oak, elm, hawthorn, apple, poplar, maple, and oak are among the summer hosts. Damage Rose leafhoppers feed on the sap of mesophyll and produce white flecking wounds (stippling) on foliage. Damage occurs early in the season, after which time the insects disperse to summer hosts. Eggs are inserted into canes, and occasionally these wounds serve as entry courts for pathogens. Distribution Throughout North America in association with rose and bramble hosts. Appearance Rose leafhopper is pale yellow to creamy white in both the adult and nymphal stages. Early-stage nymphs have reddish eyes, but those of older nymphs and adults are white. Dark spotting on the nymphs can distinguish them from white apple leafhopper. One behavioral feature of the pale yellow nymphs is that, unlike most leafhoppers, they cannot move sideways. Life History and Habits Eggs survive winter inserted into stems of rose canes, and pimple-like swellings develop where eggs are laid. At egg hatch in early spring, nymphs move to foliage and feed on the leaf underside. All nymphal stages can usually be completed in 2–3 weeks. Individuals may remain on a single leaf the entire time, but rose leafhopper nymphs are quite active and readily move forward (but not sideways) when disturbed. The winged adults usually disperse to alternate summer host plants, returning to rose in late summer for overwintering egglaying. Eggs during the summer generations are laid into large veins and petioles of leaves. In addition to the first generation on rose, two additional generations are produced during the summer. In the Pacific Northwest, peak numbers of nymphs are usually observed in early June, late July/early August, and mid-September.

284

A

B

C D

E

A. Empoasca species associated with squash. JIM KALISCH, UNIVERSITY OF NEBRASKA

F

B. Hopperburn injury to pumpkin. WHITNEY CRANSHAW

C. Western potato leafhopper. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Southern garden leafhoppers. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

E. Stippling injury produced

by western potato leafhopper. WHITNEY CRANSHAW

F. Rose leafhopper adult. DAVID SHETLAR

G. Rose leafhopper nymph. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

H. Leaf symptoms produced by rose leafhopper feeding. WHITNEY CRANSHAW

G H

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

OTHER MESOPHYLL-FEEDING LEAFHOPPERS Small white flecking wounds in leaves (stippling) are a characteristic symptom produced by leafhoppers that feed on the parenchyma cells of the mesophyll, removing cell contents. Edwardsiana commisuralis1 is a common western species that produces injuries similar to rose leafhopper on dogwood and alder. E. hippocastani occurs on elm and E. australis on mountain-ash. White apple leafhopper (Typhlocyba pomaria) is physically almost identical to rose leafhopper. It produces wounds around feeding sites that appear as whitish flecking (stippling) on leaves of apple, cherry, peach, prune, and hawthorn. Winter is spent as eggs inserted under the bark of twigs and small branches of these hosts. Nymphs are uniformly colored translucent white, occasionally yellow. Two generations typically are produced, but they overlap considerably and adults may be present from late May through October. White apple leafhopper is a major pest of apple orchards in much of North America, damaging plants by removing chlorophyll from leaves as it feeds and by excreting small dark droplets that may spot fruit. Erythroneura leafhoppers also produce white flecking wounds. Nymphs are cream-colored or slightly yellow and have some spotting. Western grape leafhopper (E. vulnerata)1 is an important pest of grapes grown in the western states. Winter is spent in the adult stage under sheltering debris in the vicinity of previously infested plants. The adults emerge when spring temperatures reach the mid-60s and fly to the vines to feed shortly after the new growth emerges. After several weeks, the females begin egg-laying, inserting the egg just underneath the leaf surface; this appears as a small bubble when closely examined. Eggs hatch in 1-2 weeks, and the nymphs feed on the mesophyll of cells on the lower leaf surface. They become full grown in approximately 3 weeks. Depending on location, three to five generations may be produced annually and may overlap and be present on plants continuously, as long as foliage remains. In fall, the adults disperse to cover for wintering. Related species have similar habits. Grape also hosts variegated leafhopper (Erythroneura variabilis) in southern California and eastern grape leafhopper (E. comes) in eastern states. Virginia creeper (ziczac) leafhopper (E. ziczac) is common in the High Plains and Rocky Mountain region where it develops on grape, Virginia creeper, elm, and Boston ivy. Threebanded leafhopper (E. tricincta) may occur on grape, Virginia creeper, and apple in the east. E. gleditsia feeds on black locust, Aesculus species, and hawthorn, and E. lawsoniana feeds on sycamore. Maple leafhopper (Alebra albostriella)1 produces stippling injuries on leaves of several trees and shrubs, including various maples, American elm, basswood, oak, beech, hickory, hawthorn, and sumac. It produces one generation per year, with peak populations observed in late spring in the East and in midsummer in central California. It overwinters as eggs inserted into twigs. Feeding by Paraphlepsius strobi1 produces purplish spotting on beets and lambsquarter.

286

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B

C D

E

F

G

H

I

A. Edwardsiana hippocastani, a leafhopper associated with elm. WHITNEY CRANSHAW

B. White apple leafhopper nymphs. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Injury produced by white

apple leafhopper. WHITNEY CRANSHAW

D. Variegated leafhopper, adult. HAROLD LARSEN, COLORADO STATE UNIVERSITY

E. Variegated leafhopper, nymphs. HAROLD LARSEN, COLORADO STATE UNIVERSITY

F. Western grape leafhopper.

J

K

TOM MURRAY

G. Zic-zac leafhoppers. HAROLD LARSEN, COLORADO STATE UNIVERSITY

H. Leafhopper damage to grape. WHITNEY CRANSHAW

I. Zic-zac leafhopper damage

to Virginia creeper. WHITNEY CRANSHAW

J. Injury produced by

maple leafhopper. WHITNEY CRANSHAW

K. Leaf spot injury to beet

produced by Paraphlepsius strobi. WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

MESOPHYLL-FEEDING LEAFHOPPERS, AND LEAFHOPPERS THAT FEED ON PHLOEM

Aster (or Sixspotted) Leafhopper (Macrosteles quadrilineatus)1 hosts An extremely wide range of plants, including small grains and turfgrasses, many vegetables, and flower crops. Damage Direct feeding effects are insignificant, producing minor spotting at most; however, aster leafhopper can transmit the phytoplasma (Candidatus Phytoplasma asteris) that produces the eastern strain of aster yellows disease. Aster yellows is damaging to head lettuce, carrot, celery, cosmos, marigold, aster, and many other garden plants. Distribution Aster leafhopper can be found throughout most of North America but is most common and important in the Midwest, northeastern U.S., and eastern Canada. Appearance Overall color of adults is usually grayish green. The presence of three pairs of dark markings on the head is the most distinguishing feature of this insect in separating it from other common leafhoppers. Life History and Habits Aster leafhopper survives poorly in areas of harsh winter temperatures but may survive as eggs as far north as New England and Manitoba if conditions are suitable. The primary wintering areas are along the Gulf of Mexico and the southern Great Plains. Winged adults are highly migratory, and large annual flights allow them to colonize a wide area each growing season, often moving on favorable winds in late May and early June. Spring grains are important hosts used after migrations, and populations may increase rapidly. Eggs are laid in leaves and stems of plants and hatch in about a week. Nymphs pass through four instars during 4–6 weeks. Adults can live for months. Two or four generations are typically produced during the growing season. Leafhoppers that feed on plants infected with aster yellows acquire the causal phytoplasma but cannot transmit the pathogen to new plants until the phytoplasma has circulated in the leafhopper and moved to its salivary glands, a period of between 10 days to 3 weeks. Typically, somewhere between 1 and 5% of all leafhoppers carry the aster yellows phytoplasma in the Midwest during the growing season. Several other leafhoppers are involved in transmitting the phytoplasma strains that produce aster yellows. In the far west and southeastern U.S., Scaphytopius irroratus1 is important in transmitting the western strain of this pathogen. Scaphytopius acutus is a vector involved in transmission in the Northeast. Other vectors include Ceratagallia abrupta,1 mountain leafhopper (Colladonus montanus),1 and Fieberiella florii.1 The latter two species are also vectors of the phytoplasma strains that produce Western X-Disease in stone fruits.

MISCELLANEOUS LEAFHOPPERS THAT FEED ON PHLOEM Beet leafhopper, Circulifer (= Neoaliturus) tenellus,1 is the vector of the virus that causes beet curly top. This produces disease in several plants, notably pepper, tomato, beet, and bean. Damage by beet leafhopper feeding in the absence of the virus is insignificant. Beet leafhopper is originally of European origin but has become widely established in the western U.S., particularly the southwest. Honeylocust leafhopper (Macropsis fumipennis)1 is common on honeylocust and many other shade trees in much of North America. Feeding produces a slight flecking of the foliage, and the insect is a minor honeydew producer. The bright green nymphs are commonly confused with those of honeylocust plant bug, and early in the season both are present on foliage. At least two generations of honeylocust leafhopper are produced annually. Macropsis ocellata is common on willow in the northeastern quadrant states, and M. graminea occurs on Populus species in the northern U.S. and Canada. Plum leafhopper (M. trimaculata) develops on stone fruits and is known to vector peach yellow leaf curl virus. 288

A

B

C D

E

F

A. Aster leafhopper. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

B. Hairy roots and witches’-broom symptomatic of aster yellows infection of carrot. WHITNEY CRANSHAW

C. Aster yellows symptoms

in statice.

WHITNEY CRANSHAW

D. Changes in flower development (phyllody) symptomatic of aster yellow infection. WHITNEY CRANSHAW

E. Fieberiella florii. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

F. Colladanus montanus. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

G H

J

K

I

G. Beet leafhopper adult. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H. Newly hatched beet leafhopper nymph and egg. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

I. Beet leafhopper nymph. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J. Honeylocust leafhopper adult. WHITNEY CRANSHAW

K. Honeylocust leafhopper nymph. WHITNEY

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

MISCELLANEOUS LEAFHOPPERS THAT FEED ON PHLOEM Whitebanded elm leafhopper (Scaphoideus luteolus)1 is important as the vector of the phytoplasma that produces elm phloem necrosis disease. The generally brown-colored nymphs are distinctive with a broad white band across the abdomen. One generation per year is produced, with winter spent as eggs inserted into twigs. Leafhoppers in the subfamily Cicadellinae are known as “sharpshooters.” These leafhoppers are generally distinguishable by having an unusually enlarged head area, often pointed. This area contains the muscles that allow them to pull out fluids from the xylem and they, along with some spittlebugs, psyllids, and treehoppers, are among the few insects that can feed on xylem fluids. The origin of the name “sharpshooter” is questionable but often proposed to be related to the insects’ ability to forcefully flick droplets of excreted watery fluids away from their bodies. Sharpshooters include some of the most brightly colored of the leafhoppers. Graphocephala coccinea,1 known variously as the “candy-striped leafhopper” or red-banded leafhopper, is a gaudily colored species with alternating bands of magenta and green or blue. It can be common on many garden flowers and caneberries but causes little injury. Egg scars on leaves of woody plant hosts may appear as small blisters on shrubs on which nymphs develop (e.g., rhododendron, laurel, azalea). The related blue-green sharpshooter, Hordnia (=Graphocephala) atropunctata,1 is more commonly associated with vines and woody plants. It is not damaging to plants on which it feeds, but it has some importance in coastal areas of California because of its ability to transmit the bacterium (Xylella fastidiosa) that produces Pierce’s disease of grape. More than a dozen other Graphocephala/Hordnia species occur in North America, many also brightly colored and patterned. Pierce’s disease is the most important pest problem of the California grape industry. The bacterium grows in the xylem of the plant and produces a progressive decline of vines, ultimately killing the plants. Of greatest importance as a vector is the glassy-winged sharpshooter (Homalodisca vitripennis),1 a species that is highly mobile and can develop on many common host plants, wild and cultivated. Citrus is a particularly important host, but other common plants on which it breeds in California include bird of paradise, eucalyptus, euonymus, crape myrtle, pittosporum, sunflower, hibiscus, xylosma, and cottonwood. Several other sharpshooters can transmit X. fastidiosa but are much less important as vectors of the Pierce’s disease pathogen in California. These include the green sharpshooter (Draeculacephala minerva)1 and the redheaded sharpshooter (Carneocephala fulgida),1 both of which breed on grasses. Xylella fastidiosa produces diseases in several other plants. In California, important diseases produced include oleander leaf scorch, almond leaf scorch, and mulberry leaf scorch. In the eastern U.S. diseases produced by X. fastidiosa include phony peach disease, plum leaf scald, and bacterial leaf scorch, which affects many common shade trees, including American elm, maple, oak, sycamore, sweetgum, and hackberry. The pathogen is also common on many other plants, including turfgrasses, but does not produce disease in many hosts. Vectors of X. fastidiosa in the eastern U.S. include several sharpshooter species, including Homalodisca insolita, Graphocephala spp., Draeculacephala spp., Oncometopia spp., and, in areas where it has spread, the glassy-winged sharpshooter. Many leafhoppers are associated with lawns and turfgrasses. None appear to cause much more than minor spotting and are not seriously damaging except during seedling establishment. Common species include lawn leafhopper (Deltocephalus hospes),1 gray lawn leafhopper (Exitianus exitiosus),1 lesser lawn leafhopper (Graminella sonora),1 painted leafhopper (Endria inimica),1 and clover leafhopper (Ceratagallia sanguinolenta).1 Several species in the genera Deltoacephalus, Draeculcephala, Forcipata, Cuerna, Latalus, Polyamia, Dikraneura, and Balclutha may also be found on turf and ornamental grasses. 1

Hemiptera: Cicadellidae

290

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B

C D

F

A. Redbanded leafhopper. DAVID SHETLAR

B. Glassy-winged sharpshooter and eggs. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Blue-green

sharpshooters. DAVID SHETLAR

E

G

D. Glassy-winged sharpshooter and adult and nymphs.

H

F. An Endria species of leafhopper. TOM MURRAY

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

G. Clover leafhopper.

E. Redheaded sharpshooter

H. A Deltocephala

TOM MURRAY

and adult and nymphs.

species of leafhopper.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

I. A Draeculacephala

TOM MURRAY

species of leafhopper. DAVID SHETLAR

I

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

LEAFFOOTED BUGS ASSOCIATED WITH FOLIAGE Leaffooted bugs (Coreidae) are moderate to large-sized insects, with a prominently projecting head possessing piercing-sucking mouthparts. Many have a pronounced flattening of the hind legs, from which the family name is derived. Most leaffooted bugs feed primarily on seeds and are discussed on page 602.

Squash Bug (Anasa tristus)1 hosts Winter types of squash, including pumpkin. Rarely, summer squash and melon are damaged. Damage Adults and nymphs suck sap from the stems and leaves, causing localized injuries that kill and collapse tissues. Initial symptoms are small yellow flecks on foliage that later turn brown. Later, foliage often wilts and dies beyond damaged areas. Feeding may occur on fruit, causing wounds that are readily colonized by rotting organisms. The wilting associated with squash bug is sometimes termed Anasa wilt of cucurbits. More recently squash bugs have been found associated with a bacterium, Serratia marcescens, that can produce cucurbit yellow vine disease. The bacteria survive winter within squash bugs and are introduced into plants when the insects feed. Yellow vine disease often produces bright yellowing of foliage, as well as more general symptoms (stunting, wilting) that can be produced by fungal root rots and bacterial wilt, making diagnosis complicated. Yellow vine disease has been found over a wide area, encompassing much of the eastern half of the U.S. Distribution Squash bug is generally distributed throughout the U.S., excluding the Northwest, and southern Canada and extending south into Central America. This species is most common and damaging in southern areas. Appearance Adults are grayish brown and about 11⁄16 inch in length. They lay distinctive shiny coppery red masses of eggs, and the newly hatched nymphs are pale green. Older nymphs are gray and develop wing pads that become increasingly prominent. Life History and Habits Squash bugs spend winter in the adult stage in protected sites around previously infested plantings. They become active and first appear and feed in June, shortly after plant emergence. At this time they mate, and females lay masses of eggs on leaf undersides and occasionally stems. After hatching, the nymphs feed together in groups, usually on the shaded undersides of the plant. Only one generation per year is produced in the northern range of squash bug, but 2 or even 3 generations may be present in more southerly areas. Adults that develop late in the season do not lay eggs and leave the field for overwintering shelter.

Related Species Horned squash bug (Anasa armigera) occurs in the southeastern U.S. as far west as Texas and occasionally damages plants in a manner similar to squash bug. Life histories are apparently also similar, but the two species differ markedly in appearance. Horned squash bug nymphs are white until the fifth instar, later turning variegated brown and yellow. Adults have a broad thorax with sharp angles. Opuntia bug (Chelinidea vittiger)1 develops on the pads of opuntia cacti. Overwintered adults move to opuntia in late spring and lay eggs in small masses. Nymphs feed on the plants and in high numbers may cause wilting. Two generations are produced annually. On cholla cacti the leaffootted bug Narnia snowi1 is often common.  Hemiptera: Coreidae

1

292

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B

C D

E

F

G H

A. Squash bugs massed on mature pumpkin.

J

WHITNEY CRANSHAW

I

F. Wilting of pumpkin due to squash bug feeding injury. WHITNEY CRANSHAW

B. Mating pair of

G. Symptoms of cucurbit

WHITNEY CRANSHAW

JOE JASINSKI, OHIO STATE UNIVERSITY EXTENSION, BUGWOOD.ORG

squash bugs.

C. Squash bug egg masses. WHITNEY CRANSHAW

D. Nymphs and associated

injury by squash bugs. WHITNEY CRANSHAW

E. Squash bugs nymphs. WHITNEY CRANSHAW

yellow vine disease.

H. Horned squash bug. JOHN CAPINERA, UNIVERSITY OF FLORIDA

I. Opuntia bug adults. WHITNEY CRANSHAW

J. Opuntia bug nymphs. WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

PLANT BUGS The plant bugs (Miridae) are a large family of moderate-sized (ca. ¼ inch) insects. The great majority feed on plant sap, but a few are predators of other insects or omnivores. When feeding on plants, plant bugs use their mouthparts in a fairly destructive manner, known as lacerate-flush, which involves physically breaking many cells and flushing the feeding wound with digestive enzymes. This produces localized areas of dead cells. Feeding on developing leaves, buds, and flowers is common among plant bugs, resulting in secondary symptoms such as distortions and abortion. Plant bugs damaging to fruit and flowers are covered on page 592.

Fourlined Plant Bug (Poecilocapsus lineatus)1 hosts Fourlined plant bug will feed on a very wide range of plants. Damage is most commonly found on perennials (especially those in the mint family or composites), but they commonly attack shrubs, including azalea, dogwood, forsythia, viburnum, and weigelia. Damage Discrete white or dark spots are originally produced at feeding sites. These damaged areas often become watery as cells die and collapse. Damage is concentrated on the younger tissues on upper areas of plants, and injuries to new growth may cause wilting or growth distortion. Distribution Northeastern quadrant of the U.S. and adjacent areas of southern Canada. Appearance Adults are yellow, sometimes green, with 4 dark stripes and have an overall length of ¼ to ⅓ inch. Immature forms are bright red-orange with black dots on the thorax. The characteristic striping becomes apparent in later stages. Life History and Habits Winter is spent as eggs, laid in small clusters in slits of shoots. Nymphs hatch in mid- to late spring and develop in about a month. Adults usually appear in July and may be present for several weeks, mating and laying eggs. One generation is produced annually.

Garden Fleahopper (Halticus bractatus)1 hosts A wide range of plants, with leaves of legumes preferred but also including garden vegetables such as pumpkin, squash, tomato, potato, beet, and pepper. This species is also found on many weeds. Damage Pale yellow spotting typically develops at feeding sites of garden leafhopper. Feeding can cause stunting and may kill seedlings. Dark fecal spots are produced that further detract from the appearance of infested plants. Distribution Eastern U.S., particularly southern areas. Appearance Adults are shiny black with yellowish legs and antennae. They are among the smallest of the plant bugs (ca. 1⁄12 inch) with females having rounded bodies and males being slender. The hind legs are greatly enlarged and allow adults to hop when disturbed, similar to flea beetles, for which they are often mistaken. Both shortwinged and long-winged females may be present. Males always have long wings. The nymphs are pale green and darken with age. Life History and Habits Garden fleahopper may winter as adults in extreme southern parts of its range but normally survives as eggs inserted into vegetation. Eggs hatch around April, and the nymphs develop over the course of a month. Numerous generations are produced (5 reported in Virginia) that overlap considerably by midseason. 294

A

B A. Fourlined plant bug adult. DAVID SHETLAR

B. Nymph of fourlined plant bug and associated injury. DAVID SHETLAR

C. Water soaked

wounds produced by fourlined plant bug feeding on cucumber.

C D E

F

WHITNEY CRANSHAW

D. Scabby callous

growth in response to leaf-feeding injuries by fourlined plant bug. WHITNEY CRANSHAW

E. Fourlined plant

bugs and associated injury to daisy. DAVID SHETLAR

F. Garden fleahopper,

adult females.

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Garden

fleahopper, adult males. JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Garden fleahopper, adults and nymphs. JIM KALISCH, UNIVERSITY OF NEBRASKA

G H

I

I. Garden fleahopper injury symptoms on squash leaf. JIM KALISCH, UNIVERSITY OF NEBRASKA

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

PLANT BUGS

Other Leaf-feeding Plant Bugs Honeylocust plant bug (Blepharidopterus chlorionis)1 is a serious pest of honeylocust in much of the northern U.S. Nymphs feed on developing buds and leaves in May and June and often kill them. Older leaves may survive but show discoloration and deformation because of localized necrosis around feeding points. Heavy infestations may greatly retard foliage development in spring and have been associated with twig and branch dieback. One generation is produced annually, with overwintering eggs inserted into twigs in June and early July. Ash plant bug (Tropidosteptes amoenus)1 produces whitish flecking wounds on leaves of ash (particularly green ash) in much of the U.S. and southern Canada. Emerging leaves that are damaged show distortion. Dark tarry spots of excrement are present around feeding sites on the leaf underside. Adults are light brown, about ⅜ inch long, with heart-shaped markings on the plate behind the head (scutellum). The nymphs are more oval, shiny yellowish or reddish brown, and lack wings. Overwintering eggs are laid under loose bark, and nymphs usually hatch in late April and May. Most injury occurs when the nymphs approach maturity in late May. A second generation occurs in July and August and adults produced in this latter generation produce the overwintering eggs. In eastern North America, Tropidosteptes brooksi may also cause spotting of ash leaves. This insect is greenish, and its life history is presumed similar to that of ash plant bug. Western ash plant bug (T. pacificus) is the common species in the Pacific States. Adults are brown and the nymphs green with black spots. Tropidosteptes illitus is a yellow and brown or black species found in western states. Plant bugs in the genus Plagiognathus1 cause leaf spotting, with damaged areas often dropping out. Close to 90 species occur in North America, and they have been collected on plants in more than 3 dozen families, but, with few exceptions, little is known about the plants on which they develop. Plagiognathus delicatus may co-occur with honeylocust plant bug on honeylocust. Plagiognathus punctatipes can be a common species associated with black walnut. Sycamore plant bug (P. albatus) develops on leaves of sycamore and planetree. Spotting injuries it produces may look like anthracnose, a common fungal disease on these plants. Yucca plant bug (Halticotoma valida)1 feeds on yucca foliage, producing white mottling marked with dark tarry spots of waste. It is found over the natural range of yucca and occurs in ornamental plantings as far north as Ohio and southern Pennsylvania. This is a small plant bug, about 3⁄16 inch, with black wings and orange-red legs, that has 3–5 generations per year in the Atlantic States. Phlox plant bug (Lopidea davisi)1 feeds on leaves, buds, and flowers of phlox. White or yellow flecking injuries are typical on leaves. Flowers and seeds are also damaged. It is a colorful species with orange immature stages (nymphs); the winged adults have both black and orange coloration. Similar injuries can be produced on hollyhock by the hollyhock plant bug (Brooksetta althaeae),1 a dark green plant bug. Leaves of royal palm in Florida now often show injuries associated with feeding by Xlastodoris luteolus,2 known as the “royal palm bug.” Leaf spotting on the underside of the leaf is a typical symptom, but in high populations large areas of leaves may show dark streaking. Ash-gray leaf bugs 3 (Parapiesma spp.) are inconspicuous insects that rarely attract the attention of a gardener but they can be common on pigweed as well as grain-producing amaranth and many related weeds common in gardens, including lambsquarters. They are gray or brown with reticulated wings held flat over the body, giving a resemblance to lace bugs. Feeding on foliage may produce minor spotting and distortion of young leaves, but seed feeding on Amaranthus has been shown to reduce yield. 1

Hemiptera: Miridae; 2 Hemiptera: Thaumastocoridae; 3 Hemiptera: Piesmatidae

296

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B

C

D

E

F

G H

A. Phlox plant bug adults and leaf injury symptoms. JIM KALISCH, UNIVERSITY OF NEBRASKA

I

J

B. Honeylocust plant bug adult. WHITNEY CRANSHAW

C. Honeylocust plant bug nymphs

massed on twig.

JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Ash plant bug nymphs and injury. DAVID SHETLAR

E. Ash plant bug adult. DAVID SHETLAR

F. Walnut plant bug adult. WHITNEY CRANSHAW

G. Sycamore plant bug nymph. DAVID SHETLAR

K

L

H. Sycamore plant bug injury. DAVID SHETLAR

I. Royal palm bugs and

associated injury.

DOUG CALDWELL, UNIVERSITY OF FLORIDA

J. Royal palm bugs. LYLE J. BUSS, UNIVERSITY OF FLORIDA

K. Yucca plant bugs. DAVID SHETLAR

L. Ash-gray leaf bugs. DAVID SHETLAR

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

Life stages of the hairy chinch bug. DAVID SHETLAR

HAIRY CHINCH BUG

(Blissus leucopterus hirtus)1

hosts Most turfgrass species, but Kentucky bluegrass and bentgrasses are particularly damaged; perennial ryegrass and fine fescues can be damaged if they lack endophytic fungi. Damage Chinch bug feeding apparently interferes with the ability of plants to transport water. Damage resembles that caused by drought and tends to occur in patches, with killed turfgrass appearing strawlike and failing to respond to watering. Distribution Hairy chinch bug is a common species throughout the Midwest, northeastern U.S., and southeastern Canada. Appearance Adults are about 1⁄6 inch, gray-black, and covered with fine hairs. Wings are white with a dark spot in the middle. Forms of chinch bugs with short wings are common. Young nymphs have a bright orange abdomen that darkens to blue-black as they develop. Life History and Habits Hairy chinch bug winters in the adult stage, at the base of grass stems among the thatch. It becomes active when daytime temperatures begin to regularly reach 70° F. From Pennsylvania west to Nebraska two generations per year are produced. Into southern Canada, one generation occurs. The bugs usually begin laying eggs from mid-April through May. Egg-laying begins later but occurs over a longer period in northern areas. The eggs are laid in leaf sheaths or thatch, with peak egg-laying in the New Jersey area approximately when white clover is in peak bloom. The nymphs feed for about 4–6 weeks and may occur in large masses in midsummer. The second generation usually peaks in late August and early September. Damage from the second generation rarely occurs when the turf has entered summer dormancy. The fungus Beauveria bassiana and the predatory big-eyed bugs (Geocoris spp.) are particularly important in biological control of hairy chinch bug.

Related and Similar Species Southern chinch bug (Blissus insularis) is an important pest of turf from South Carolina to Oklahoma and south. It is very similar in appearance to hairy chinch bug, but their ranges do not overlap. Several warmseason grasses are hosts, but southern chinch bug is most damaging to St. Augustinegrass. Three or four generations are typically produced annually, with peak damage by summer generations occurring during hot, dry weather. Western chinch bug (B. occiduus) is a species that has been reported damaging to buffalograss in the Central Plains, where it is also known as the “buffalograss chinch bug.” Overwintering populations consist primarily of short-winged forms. A mixture of long-winged and short-winged (brachypterus) forms occurs during the summer. The general life history appears to be similar to that of hairy chinch bug. Common chinch bug (B. leucopterus leucopterus) is generally distributed throughout the central U.S. It can be a serious pest of small grains, sorghum, and corn in the Midwest but rarely causes significant injury to turfgrass. 298

A. Hairy chinch bug adults, showing shortand longer-winged forms. DAVID SHETLAR

B. Lawn area showing

chinch bug injury. DAVID SHETLAR

A

B

C

D

E

F

C. Hairy chinch bug

nymphs exposed around the base of grass plants. DAVID SHETLAR

D. Adult and nymph of the southern chinch bug. DAVID SHETLAR

E. Western chinch

bug adults, showing short- and longer-winged forms. JIM KALISCH, UNIVERSITY OF NEBRASKA

G H

I

F. False chinch bug adults. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. False chinch bugs,

mixed life stages. WHITNEY CRANSHAW

H. Damage to lettuce

by false chinch bugs. WHITNEY CRANSHAW

I. False chinch bugs

massed on drying seed pods. WHITNEY CRANSHAW

False chinch bugs J(Nysius spp.)2 are about 1⁄6 inch, winged, and slightly more elongate in form than “true” chinch bugs (Blissus spp.). General coloration is mottled gray, with the thorax and head somewhat darker. Nymphs are gray-brown and have some reddish or orange markings on the abdomen. False chinch bugs are generally distributed throughout most of western North America but are particularly common in the High Plains and Intermountain West. False chinch bugs suck the sap from plants during feeding. The adults also commonly aggregate and occur in large numbers on individual plants, causing plants to wilt and die rapidly. Outbreaks are sporadic but can destroy plantings, particularly early in the year. Later in the season, aggregations tend to be greatest on developing seed heads. False chinch bugs are sometimes a nuisance pest of homes and buildings during hot summers when they may migrate into buildings. Most garden plants can be damaged during outbreaks; crucifers and beet family plants are favored. Wild hosts include many weeds such asGtansy mustard, kochia, Russian thistle, and sagebrush. False chinch bugs spend the winter as nymphs or adults under protective debris near winter annual mustards they use for hosts. They become active in early spring and move to developing mustards to feed. Adults lay eggs in loose soil or soil cracks around plants and eggs hatch in about 4 days. Under summer conditions, the wingless, gray nymphs feed for about 3 weeks and then reach the adult stage. Adults live for several weeks, fly readily, and can disperse over wide areas. About three generations are usually produced, with peak numbers often appearing in July and early August. 1

Hemiptera: Blissidae; 2 Hemiptera: Lygaeidae

299

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

STINK BUGS THAT FEED PRIMARILY ON LEAVES Stink bugs (Pentatomidae family) are moderately large insects, about ½ inch long, with a characteristic, broad shield form. Most species produce a disagreeable odor when handled. Most are rather uniform green or brown, but some species have bold patterning. Nymphs are generally similar to adults in appearance but tend to be more rounded in form and often have distinct patterning on the abdomen. Stink bug eggs are laid in masses and are a unique form, barrel-shaped and often with distinct spines around the top. Stink bugs feed with mouthparts designed to suck sap but also cause localized injury around the feeding site. On foliage this often results in a somewhat cloudy area surrounding a central feeding puncture. Feeding is often concentrated on younger foliage, resulting in leaf distortions and dieback. Plant-feeding stink bugs are damaging primarily to the fruiting parts of plants. Young fruit may abort from stink bug damage. Seeds of legumes are sometimes killed or shrunken following pod feeding. Fruit that has limited injury may continue to grow, but indented areas develop at the feeding site, producing an injury known as catfacing, discussed in more detail on page 594. Many stink bugs, such as twospotted stink bug, Florida predatory stink bug, and spined soldier bug, are beneficial predators of other insects (page 628). A few others, such as rough stink bugs (page 595), may feed on both plants and insects. Harlequin Bug (Murgantia histrionica)1 is a gaudily colored insect that feeds primarily on various mustard family (Brassicaceae) plants, with cabbage and mustards grown for greens among those plants most seriously damaged. However, harlequin bug will occasionally feed on a fairly wide variety, and some plants, notably cleome (spider plant), are also highly favored. Areas around the feeding site typically turn cloudy, and when the insect feeds on young tissue, growth develops in a distorted manner and may turn brown and die. It is widely distributed throughout the southern U.S. All stages of this insect are brightly patterned with red, white, and black. Adults have the typical broad form of a stink bug, about ⅜ inch in length. Nymphs have a more rounded shape with similar coloration. Harlequin bugs normally survive winters only in the adult stage, hidden in protected sites such as crop debris, and do not undergo true dormancy. The adults emerge from winter shelter in mid-spring and typically feed first on wild mustard weed hosts. By June or early July they may be found in gardens, feeding on cabbage, radish, and other crucifers. Females then lay masses of eggs that resemble rows of small black-and-white banded barrels on the leaves of these plants. The immature nymphs usually develop in the same plants where eggs were laid and feed for about 2 months before becoming full grown. If warm weather persists, 3 and sometimes 4 generations are produced annually. Another brightly colored stink bug that feeds on plants of the cabbage family is the painted bug (Bagrada hilaris),1 also known as the “bagrada bug.” It is much smaller (¼ inch) than the harlequin bug but can cause similar damage to the growing leaves of many crop plants. Wild mustards are important early season hosts and in high populations non-brassica crops may be injured. The present distribution of this insect, native to Africa, now includes areas within most of the southwestern states. The kudzu bug (Megacopta cribraria)2 is a recently introduced species to North America, first detected (2009) in Georgia. Since then it has steadily spread in the southeastern U.S. and is presently known from parts of the Carolinas, Georgia, and Alabama. It feeds primarily on the leaves and stems of various legumes, including kudzu, kidney bean, soybean, and lima bean. In high numbers they can cause significant crop losses, but this insect also attracts attention and concern as it has a habit of massing on the sides of buildings in autumn.  Hemiptera: Pentatomidae; 2 Hemiptera: Plataspidae

1

300

B

A

D

C

E A. Harlequin bugs on cabbage. WHITNEY CRANSHAW

B. Harlequin bug egg mass. WHITNEY CRANSHAW

C. Harlequin bug egg mass

just after hatch. WHITNEY CRANSHAW

D. Harlequin bug nymphs. WHITNEY CRANSHAW

E. Plant injury produced

F by harlequin bugs. G

H

WHITNEY CRANSHAW

F. Harlequin bug adults

showing range in coloration. WHITNEY CRANSHAW

G. Kudzu bug. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

H. Massed kudzu bugs. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

I. Painted bugs. SURENDRA K. DARA, UNIVERSITY OF CALIFORNIA COOPERATIVE EXTENSION SAN LUIS OBISPO COUNTY, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROJECT

I

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

LACE BUGS The lace bugs (Tingidae family) are relatively small insects (ca. 1⁄5 inch) with delicately sculptured wings held flat over the back. They feed on the underside of leaves, producing irregular white or yellow spotting that is evident on the upper leaf surface. Droplets of a varnishlike excrement are also deposited around feeding sites, assisting in diagnosis. More than 150 lace bug species occur in North America, with many of the most damaging species occurring in the eastern coastal states. Members of the genus Stephanitis1 are associated with broadleaf evergreens, and the injuries they produce are particularly conspicuous on these plants since they retain their foliage. These lace bug species winter as eggs inserted into or cemented to leaves with a covering of crusty dark excrement. Eggs hatch in late spring, and there may be 2 generations. Azalea lace bug (S. pyrioides) is the most damaging lace bug associated with landscape plants, producing severe injury to azalea foliage. It is particularly damaging in the southeastern and Mid-Atlantic states but occurs over a broad area in the eastern U.S. where azalea is grown and recently became established in the Pacific Northwest, where it has shown high potential to cause injury. On rhododendron and mountain laurel along the East Coast, a similar type of leaf injury is produced by the rhododendron lace bug (S. rhododendri). Andromeda lace bug (S. takeyai) develops on Japanese andromeda, with leucothoe, styrax, and willow as incidental hosts. Corythuca1 is the largest and most diverse genus of lace bugs, and most of the 50-odd species in this genus develop on woody plants. All winter as adults under protective cover in the vicinity of previously infested plants. Eggs are laid in small groups inserted into leaf veins. Development typically takes about a month, and two generations are produced annually by most species. Hawthorn lace bug (C. cydoniae) is probably the most commonly encountered species in this group of lace bugs. It occurs throughout most of the U.S. and southern Canada and is associated with various roseaceous plants, particularly hawthorn, cotoneaster, amelanchier, quince, and pyracantha. Some differences in susceptibility to injury among different species and cultivars have been identified. Other commonly encountered lace bugs in this group include oak lace bug (C. arcuata) on various oaks; birch lace bug (C. pallipes) on birch, maple, and mountain-ash; angulate tingid (C. angulata) on ceanothus; sycamore lace bug (C. ciliata) on sycamore; hackberry lace bug (C. celtidis) on hackberry; elm lace bug (C. ulmi) on elm; walnut lace bug (C. juglandis) on walnut, butternut, and basswood; and cherry lace bug (C. pruni) on cherry, chokecherry, and raspberry. A few species of lace bugs are also found on herbaceous plants. Chrysanthemum lace bug (Corythuca marmorata) occurs on goldenrod, aster, and chrysanthemum. Nymphs and adults can be found on upper leaf surfaces. Distinct lace bug (C. distincta) is most commonly found feeding on various thistles (Cirsium) and can be common on Canada thistle. Eggplant lace bug (Gargaphia solani)1 is a minor pest of eggplant in parts of the central and southern U.S. This species has the unusual habit of adult guarding of eggs and young nymphs. Basswood lace bug (G. tilia) is common on linden and basswood in the midwestern states. Lantana lace bug (Teleonemia scrupulosa)1 is native to parts of Florida and Texas, occurring naturally southward into northern Chile. It develops on the underside of leaves of lantana and sage, producing the characteristic spotting typical of other lace bugs. Since lantana has become a noxious weed in some areas of the world where the plant was introduced, lantana lace bug has been introduced to assist in its control.  Hemiptera: Tingidae

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B

C

D

E

F

G

H

I

A. Injury produced by rhododendron lace bug. DAVID SHETLAR

B. Egg mass of the

rhododendron lace bug. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Adult of the

rhododendron lace bug. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Rhododendron lace bug nymph. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J

K

E. Azalea lace bug damage. WHITNEY CRANSHAW

F. Adults and nymphs of

azalea lace bug. DAVID SHETLAR

g. Sycamore lace bugs,

mixed stages. DAVID SHETLAR

H. Walnut lace bugs, mixed stages. DAVID SHETLAR

L M

I. Injury symptoms on upper leaf surface from cherry lace bug. WHITNEY CRANSHAW

J. Injury symptoms on lower leaf

surface from cherry lace bug. WHITNEY CRANSHAW

K. Foliage bronzing produced

by hawthorn lace bug. DAVID SHETLAR

L. Chrysanthemum lace bug. JIM KALISCH, UNIVERSITY OF NEBRASKA

N O

M. Eggplant lace bug. WHITNEY CRANSHAW

N. Damage produced by lantana

lace bug.

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SERVICE, BUGWOOD.ORG

O. Lantana lace bug. CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SERVICE, BUGWOOD.ORG

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

THRIPS Thrips are minute insects, rarely more than 1⁄16 inch, of elongate form. The order name, Thysanoptera, means “fringe wing,” a reference to the fringe of long hairs on both pairs of narrow wings. Thrips also possess unusual mouthparts, with a single mandible that functions as a spike to puncture the leaf surface and a pair of finer stylets (maxillae) that penetrate interior cells. Thrips then suck the released fluids. Plant injuries appear typically as silvery scars marked with small varnishlike fecal droppings. Feeding by some thrips cause leaves to fold, roll, or curl. Despite their small size, thrips that land on human skin may produce a bite that can be felt as a very mild pinprick. Thrips that develop primarily in flowers, such as the “flower thrips” group (Frankliniella spp.), are discussed more thoroughly on page 590. Predaceous thrips are discussed on page 628. The biology of thrips is unusual as well. Eggs of most species are inserted into plant tissue. Two active feeding stages (larvae) subsequently occur. These are followed by two inactive and nonfeeding stages (prepupa and pupa) which usually develop in soil. Note: The common name for insects of this order, “thrips,” is both singular and plural. Use of the word “thrip” in any context is incorrect.

Onion Thrips (Thrips tabaci)1 hosts An extremely wide range, with onion, cabbage, and bean among the most commonly damaged plants. Onion thrips is often the most common thrips found on leaves of vegetables and flowers. Damage During feeding, onion thrips puncture the leaf surface and remove cell sap. Damaged areas appear as light flecking wounds and silvery scars, often with dark fecal spots. Newly expanding leaves may curl when damaged, and some varieties of cabbage react to injuries by producing wartlike growths. Onion thrips may vector viruses in the Tospovirus group, such as tomato spotted wilt virus, impatiens necrotic spot virus, and iris yellow spot virus. Distribution Throughout North America, common. Appearance Adults are usually yellowish or yellow-brown, tending to be darker with cooler weather. Larvae are creamy yellow. Life History and Habits Onion thrips overwinters in the adult stage throughout its range in protected sites and old plant materials. It may also be introduced into a field on infested transplants and is common on onion sets. Eggs are inserted into leaves and stems. They hatch in about one week and pass through two wingless feeding stages as larvae on the plant for about two weeks. These are followed by two nonfeeding stages (“prepupa,” “pupa”) that occur in the soil or in crevices on the plant. The winged adult stage commonly disperses throughout an area and may fly long distances aided by winds. Several generations occur annually, and all life stages may be present by early spring.

Other Thrips Associated with Foliage Gladiolus thrips (Thrips simplex) feeds on lily, iris, and gladiolus, although damage is restricted to the last. Feeding at the base of emerging leaves produces silvery scarring, that later often turns brown. Infestation of flowers produces serious scarring and often distortion. Heavy infestations can prevent flower production. Gladiolus thrips can also damage the corms in storage, causing them to become sticky and dark from plant sap at wounds. Infested corms produce poorly when replanted and are the primary source of new infestations, as gladiolus thrips fail to survive outdoors in most areas. Daylily is occasionally infested by daylily thrips (T. hemerocallis). 304

B

A C D

E

F A. Adult onion thrips. ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

B. Leaf injury to onion produced by onion thrips. WHITNEY CRANSHAW

G

C. Onion thrips nymphs and injury to base of onion leaf. WHITNEY CRANSHAW

D. Onion thrips and injury to cabbage. WHITNEY CRANSHAW

E. Scabby spotting produced in response to onion thrips injury to cabbage. GERALD HOLMES, CALIFORNIA POLYTECHNIC STATE UNIVERSITY AT SAN LUIS OBISPO, BUGWOOD.ORG

F. Gladiolus thrips. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Leaf injury produced by gladiolus thrips. WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

THRIPS Melon thrips (Thrips palmi) is a tropical species that became established in southern Florida in the early 1990s. High populations develop on leaves, which become yellow or white and prematurely die. Melon, squash, tomato, pepper, and potato have been particularly damaged. Introduced basswood thrips (T. calcaratus) is broadly distributed in the upper midwestern and northeastern U.S. It feeds on several hardwood trees, but American basswood is particularly susceptible and the only plant seriously damaged. Introduced basswood thrips has a single late-spring generation that appears on plants around bud break. A small amount of feeding at this time may cause basswood buds to die and drop. Eggs are laid in newly expanding leaves, and feeding may cause defoliation. Pear thrips (Taeniothrips inconsequens)1 is an introduced species now found throughout the northeastern quadrant of North America and in regions of the Pacific Northwest. It develops on several fruit trees and is of some concern to orchardists; however, it has been most damaging to sugar maple, causing leaf distortion as new foliage emerges and premature defoliation during outbreaks. Privet thrips (Dendrothrips ornatus)1 produces foliage flecking primarily on California and regal privet but it can also attack lilac and ash. Adults are generally brown with thin light bands on each of the abdominal segments. Multiple generations are produced beginning in late spring. Toyon thrips (Rhyncothrips ilex)1 develops on the new growth of Christmas berry, causing twisting and curling of foliage during spring. Adults are black and nymphs orangish. Only one generation is produced annually. Iris thrips (Iridothrips iridis)1 can be very damaging to Japanese iris, as feeding injuries scar leaves. Nymphs are white and can thus be distinguished from nymphs of other thrips associated with iris. Greenhouse thrips (Heliothrips haemorrhoidalis)1 develops on the foliage of a wide variety of plants, including avocado, viburnum, dogwood, azalea, grape, palms, orchids, philodendron, maples, magnolia, dahlia, ferns, and hibiscus. It is a common outdoor pest in southern California and Florida but restricted to indoor plants in areas of temperate climate. Greenhouse thrips feed primarily on foliage, first on the lower surface and often later moving to the upper surface of shaded leaves. Damage typically appears as discolored areas between the lateral veins. Leaf distortion and dimpling of fruit can also occur. Small droplets of reddish fluid, later turning black, are excreted. Adult greenhouse thrips are fairly small (ca. 1⁄25 inch) and dark black with a silver sheen. Larvae are pale yellowish with red eyes. Banded greenhouse thrips (Hercinothrips femoralis)1 may also scar foliage of indoor-grown plants, including African violet, chrysanthemum, fig, gardenia, jasmine, tomato, dieffenbachia, hoya, philodendron, rubber tree, and schefflera. Adults are generally brown with white patches on the forewing. Bean thrips (Caliothrips fasciatus)1 feed primarily on the underside of leaves, typically concentrating feeding at points in the leaf surface. This results in conspicuous white spotting along with which are dark fecal droplets. Legumes are the most common hosts, but they can be found on a considerably wider range of plants, including some grasses, and are a common insect contaminant of navel oranges. More than a dozen Anaphothrips species occur in North America, all of which develop on grasses. Anaphothrips obscurus1 is common on many grasses, including turfgrasses and small grains, and has been associated with earlyseason turf injury during periods in the Rocky Mountain region. These thrips are occasionally associated with biting human skin when turfgrasses enter periods of dormancy.

306

A D

B

C

A. Melon thrips. FLORIDA DIVISION OF PLANT INDUSTRY, FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES, BUGWOOD.ORG

E

B. Nymphs of pear thrips. DAVID SHETLAR

C. Pear thrips adult. PENNSYLVANIA DEPARTMENT OF CONSERVATION AND NATURAL RESOURCES–FORESTRY, BUGWOOD.ORG

D. Leaf injury symptoms produced by pear thrips. DAVID SHETLAR

E. Privet thrips adults. DAVID SHETLAR

F. Privet thrips nymphs. WHITNEY CRANSHAW

G. Privet thrips leaf injury. WHITNEY CRANSHAW

H. Nymph of a grass thrips,

Anaphothrips species.

KEN GRAY COLLECTION, OREGON STATE

F

I. Greenhouse thrips. WHITNEY CRANSHAW

J. Injury symptoms

produced by bean thrips. WHITNEY CRANSHAWUNIVERSITY

H I

J

G

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

THRIPS Chilli thrips (Scirtothrips dorsalis)1 is a relatively recent introduction (Florida in 1991 and Texas in 2005) that is becoming a major pest of many plants, including field and vegetable crops, ornamental trees, shrubs, and flowers. The thrips are small and generally light colored, though the adults have black hairs on their wings. The typical thrips life cycle is followed, though all stages tend to stay on the plant. This pest causes severe scarring of leaves, stems, and fruits and is a capable vector of several viruses that produce plant disease. Thrips in the genus Frankliniella are generally known as “flower thrips” as they often develop in flowers and may damage developing fruit and seedpods (page 590); however, they also feed on foliage, sometimes producing serious leaf scarring and distortion of new growth. Important species include western flower thrips (F. occidentalis), flower thrips (F. tritici), and tobacco thrips (F. fusca). Many are also important as vectors of tospoviruses that cause plant disease, including tomato spotted wilt and impatiens necrotic spot. Redbanded thrips (Selenothrips rubrocinctus)1 is a tropical species that occurs in parts of Florida. Mango, avocado, and sweetgum are among the most common hosts and may be disfigured by the leaf scarring and conspicuous dark fecal spotting produced by the thrips. Cuban laurel thrips (Gynaikothrips ficorum)2 is most commonly associated with Ficus nitida and F. microcarpa, producing spotting and thickened leaf folds of new growth. They are fairly large thrips (ca. ⅛ inch) and adults are jet black. Adults move to the emerging leaves and induce a leaf fold, within which they lay a large group of eggs and where the pale yellow nymphs develop. A closely related species, the weeping fig thrips (G.  uzeli), is also present in the southeastern states and, more recently, in southern California, where it is damaging primarily to weeping fig (F. benjamina). 1

Thysanoptera: Thripidae; 2 Thysanoptera: Phlaeothripidae

below: Ring spot symptoms on fruit produced by tomato spotted wilt. WHITNEY CRANSHAW

right: Western flower thrips injury to bean leaf. WHITNEY CRANSHAW

308

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B

C

D

E

F

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A. Chilli thrips. ANDREW DERKSEN, USDA-APHIS, BUGWOOD.ORG

B. Western flower thrips, adult. LYLE BUSS, UNIVERSITY OF FLORIDA

C. Western flower thrips, larva. LYLE BUSS, UNIVERSITY OF FLORIDA

D. Western flower thrips,

nonfeeding-stage “pupa.” LYLE BUSS, UNIVERSITY OF FLORIDA

E. Nymphs of western flower

thrips and leaf injury.

JIM KALISCH, UNIVERSITY OF NEBRASKA

I

J

F. Leaf curling produced on

basil by western flower thrips feeding injury.

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Seedling injury produced

by flower thrips.

JOHN C. FRENCH SR., UNIVERSITIES: AUBURN, GA, CLEMSON, AND U OF MO, BUGWOOD.ORG

H. Ring spot symptom produced by infection with tomato spotted wilt. GERALD HOLMES, CALIFORNIA POLYTECHNIC STATE UNIVERSITY AT SAN LUIS OBISPO, BUGWOOD.ORG

I. Necrotic lesions on stem produced by infection with tomato spotted wilt.

K

L

GERALD HOLMES, CALIFORNIA POLYTECHNIC STATE UNIVERSITY AT SAN LUIS OBISPO, BUGWOOD.ORG

J. Redbanded thrips. LYLE BUSS, UNIVERSITY OF FLORIDA, BUGWOOD.ORG

K. Cuban laurel thrips. DAVID SHETLAR

L. Leaf curling produced

by weeping fig thrips.

DOUG CALDWELL, UNIVERSITY OF FLORIDA

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

SPIDER MITES Spider mites (Tetranychidae family) include the great majority of plant-feeding mites that cause serious injuries. Characteristic damage is caused as they feed by penetrating outer cell layers with their mouthparts (chelicerae) and extracting plant fluids. This feeding produces characteristic flecking or discoloration and decreases the vigor of plants. Spider mite development typically involves five stages. The life cycle starts with eggs, which hatch to produce tiny, six-legged larvae. There follow two eight-legged immature stages (protonymph, deutonymph) and finally the adult. An inactive stage, called the chrysalis, precedes each molt. Where both males and females occur, the males are somewhat smaller. Males may be produced only at some periods and are unknown for some spider mites. Reproduction is asexual in their absence. All spider mites are difficult to observe except with the use of a hand lens or other magnification. Many species are quite hard to distinguish, and the use of body color to separate species is unreliable.

Twospotted Spider Mite (Tetranychus urticae)1 hosts Rose, viburnum, winged euonymus, wisteria, dogwood, pear, raspberry, bean, butterfly bush, marigold, impatiens, and hundreds of other plants. Twospotted spider mite has the widest host range of any spider mite in the world. It is also the most common mite pest of houseplants. Damage Pale flecks (stippling) may appear at feeding sites as a result of loss of cell contents. A more generalized bronzing or reddish discoloration often develops as damage progresses. Vigor of plants may be seriously reduced, and premature leaf drop often occurs on heavily infested plants. Visible webbing is produced when populations on plants are high and there is no rain or overhead irrigation. Many populations of twospotted spider mite show a high resistance to pesticides, often making management much more complex than for most other spider mites. Distribution Throughout North America. It is the most commonly damaging spider mite worldwide. Appearance Generally straw-colored with a dark blotch along each side of the body. (Note: This character of having two dark spots is shared by several other mite species.) At the end of the season or at other times of colony stress, reddish orange forms develop, which indicate the mites are in a semidormant condition. A reddish form of twospotted spider mite, known as the “carmine spider mite” (formerly Tetranychus cinnabarinus) predominates in the southern U.S. Life History and Habits Twospotted spider mite is a warm-season species, its greatest activity occurring with warmer weather. Winter is spent as a semidormant adult female, usually under sheltering debris in the vicinity of previously infested host plants. A few may winter under bark cracks or other protected sites. Early spring feeding usually occurs on weeds and other herbaceous perennials. Much of the early-season feeding may occur at these sites before the mites move to shrubs and trees. Subsequent dispersal can also include being windblown, as mites move to tips of foliage and spin out some silk to be carried by air currents. During the growing season, the life cycle of twospotted spider mite follows the pattern of life stages common to other spider mites (i.e., egg, larva, protonymph, deutonymph, adult). Under favorable conditions of warm temperature and low humidity, generations are completed in as few as 10 days, but time to complete a generation can be greatly extended under cooler conditions. Adult females may lay 5 or more eggs per day over the course of 2–3 weeks. Late in the growing season, less-active nonfeeding females are produced. These females are orange-red and migrate to sheltered areas until more favorable conditions indicate the recurrence of host plants. Under protected conditions such as the inside of greenhouses, however, twospotted spider mite can breed continually without the production of dormant forms. 310

A

B

C D

E

F

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A. Twospotted spider mites, mixed stages. DAVID CAPPAERT, BUGWOOD.ORG

B. Twospotted spider

mite and egg.

F. Leaf injury symptoms on cucumber produced by twospotted spider mite. WHITNEY CRANSHAW

G. Webbing associated

C. Twospotted spider

with heavy infestation of twospotted spider mite on rose.

DAVID SHETLAR

H. Twospotted spider

DAVID CAPPAERT, BUGWOOD.ORG

mite nymph (top) and adult male (bottom).

D. Twospotted spider mites and shed skins. DAVID SHETLAR

E. Heavy infestation of

twospotted spider mite on underside of leaf. WHITNEY CRANSHAW

JIM KALISCH, UNIVERSITY OF NEBRASKA

mites travelling on webbing. DAVID CAPPAERT, BUGWOOD.ORG

I. Twospotted spider mites

with orange color change associated with dormancy. DAVID CAPPAERT, BUGWOOD.ORG

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

SPIDER MITES

Related Species Fourspotted spider mite (Tetranychus canadensis)1 is found in the eastern U.S. and Canada, feeding on shade trees such as elm, basswood, horsechestnut, and poplar. Schoene spider mite (T. schoenei) is a very closely related species also found on a wide variety of woody plants. On rare occasions high numbers sometimes produce extensive sheeting of webs on trunks and branches. McDaniel mite (T. mcdanieli) is associated predominantly with fruit crops in the northern U.S. and southern Canada. Outbreaks are associated with prolonged hot, dry weather, and early symptoms include upward curling of the new growth. Strawberry spider mite (T. turkestani) can be common on strawberry in the southern U.S. and California.

European Red Mite (Panonychus ulmi)1 hosts Orchard trees are most seriously damaged, but many rosaceous plants including cherry laurel, crabapple, hawthorn, mountain-ash, buckthorn, amelanchier, and pyracantha are hosts. Damage Cells of the upper leaf surface are destroyed and cell contents removed, reducing photosynthesis. Bronzing is a typical reaction of European red mite infestation, and leaves may prematurely drop. Distribution Throughout most of North America; particularly abundant in northern U.S. and southern Canada. Appearance Eggs are bright red and have a unique tiny stalk (stipe) arising from the center. Newly hatched larvae are orange-yellow but darken soon after feeding. Most stages are brick red, with some greenish coloration shortly after molt. The base of the hairs on the body (setae) is whitish. Life History and Habits Winter is spent as eggs on smaller branches and twigs, usually packed into areas of roughened bark and on the underside of branch forks. Eggs begin to hatch in late April or early May, around the time of tight cluster stage of apple. Most eggs hatch within a period of 10 days, and the larvae move to leaves, settling into leaf folds to feed. They go through a brief inactive stage, molt, and resume feeding. The adult stage is reached a few weeks after eggs hatch. Adults live for approximately 2 weeks and lay 1–2 dozen eggs. Up to 7 generations per year are reported to occur in New York. On individual plants, numbers usually decline sharply because of reduced food quality after bronzing of leaves appears.

Spruce Spider Mite (Oligonychus ununguis)1 hosts Most conifers, but injury is particularly common on spruce, arborvitae, hemlock, juniper, and Fraser fir grown for Christmas trees. Damage Sap is removed and tiny light-colored flecks are produced at feeding sites on needles. Infested trees become yellowish or grayish and may prematurely defoliate. Peak feeding injury occurs in late spring and fall, but symptoms of injury intensify during summer. Distribution Widespread and particularly common in the northern U.S. and Canada. Appearance Dark green (almost black) or dark red, depending on the season and/or host. Newly hatched mites are light salmon to pale red. Only a single dark area covers most of the abdomen, which, along with the host plant, separates this species from twospotted spider mite. During heavy infestations, spruce spider mite may produce a fine netting of silk that can envelop the needles. Eggs have a small protrusion (stipe). Life History and Habits Spruce spider mite is a cool-season species, most active in spring and fall. It spends the winter in the egg stage, attached to the bark of branches, near the base of needles, and around buds. Eggs begin 312

B

C D

E

A F

G

A. Massive webbing on trunk produced by Schoene spider mite. DAVID SHETLAR

B. Schoene spider mites with

coloration associated with dormant condition. DAVID SHETLAR

C. European red mite. DAVID SHETLAR

D. European red mite,

male and female. DAVID SHETLAR

E. Leaf injury symptom produced

by European red mite.

I

DAVID SHETLAR

H

F. Eggs produced by European

red mite.

DAVID SHETLAR

G. Spruce spider mite injury

to spruce.

JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Spruce spider mites on new growth of spruce. JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Spruce spider mite with eggs. WARD STRONG, BC MINISTRY OF FORESTS, BUGWOOD.ORG

to hatch in mid-spring, and under optimal conditions a generation can be completed in 2–3 weeks. Feeding is originally concentrated on older needles of the plant interior; later, spruce spider mites move to newer growth. Females lay about 30–40 eggs, tending to lay more at cooler temperatures. When temperatures consistently exceed 80° F, populations decline and many eggs go into dormancy (aestivation). As a result, populations usually peak by late spring; however, a few individual mites remain throughout summer in the cooler parts of the canopy. A resurgence of populations occurs in September and October. Six or more generations per year are reported from Pennsylvania. 313

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

SPIDER MITES

Related Species Southern red mite (Oligonychus ilicis)1 is the most important spider mite pest of broadleaf evergreens in the eastern U.S. Holly, camellia, and azalea are among the most commonly damaged ornamental hosts. This is also a cool-season species, most active in spring and fall with most individuals going dormant with high summer temperatures. Winter is spent as red eggs on the underside of foliage. The general color of nymphs and adults is dark reddish brown. No silk is produced by southern red mite. Oak mite (O. bicolor) develops on oak, birch, chestnut, hickory, beech, and elm. It is a warm-season species that concentrates feeding on the upper leaf surface, producing leaf bronzing that is most severe in mid- to late summer. Oak mite is most commonly found in the Northeast and Midwest but has been found as far west as Arizona. OTHER SPIDER MITES FOUND ON WOODY PLANTS IN NORTH AMERICA SCIENTIFIC NAME

COMMON NAME

HOST, COMMENTS

Bryobia rubrioculus Eotetranychus carpini borealis Eotetranychus hicoriae Eotetranychus lewisi Eotetranychus matthyssei Eotetranychus populi Eotetranychus querci

Brown mite Yellow spider mite Pecan leaf scorch mite Lewis spider mite Elm spider mite

Eotetranychus tiliarium

Linden spider mite

Tree fruits; transcontinental Apple, pear; northwest states Pecan, hickory, horsechestnut, oak; southeastern U.S. Citrus, poinsettia, ceanothus American and other elms Poplar, willow Pin oak Linden; occasionally sycamore, horsechestnut, hawthorn, willow Poplar, willow Grape, apple, pear, oak, elm, boxelder; West Coast Spruce, juniper, incense cedar Boxwood; common and damaging Maple; eastern North America Baldcypress; southern U.S. Pine; southern half of U.S. to Pennsylvania Tree fruits, related rosaceous plants Sycamore, oak; southwestern U.S. Ponderosa pine; western U.S. Hickory, pecan Raspberry, blackberry, kudzu, bean, wild rose Citrus Arborvitae, cypress, tamarisk, juniper; southwestern and Rocky Mountain States Honeylocust Juniper, cupressaceous conifers; eastern U.S. Hickory, ash; southeastern U.S. Magnolia; Gulf States Grapes; California, Pacific Northwest

Eotetranychus weldoni Eotetranychus willametti Eurytetranychus admes Eurytetranychus buxi Oligonychus aceris Oligonychus boudreauxi Oligonychus milleri Oligonychus newcomeri Oligonychus platani Oligonychus subnudus Oligonychus viridis Panonychus caglei Panonychus citri

Willamette mite Admes spider mite Boxwood spider mite Maple spider mite

Plantanus spider mite Ponderosa pine spider mite Raspberry red mite Citrus red mite

Platytetranychus libocedri Platytetranychus multidigituli Honeylocust spider mite Platytetranychus thujae Arborvitae spider mite Tetranychus humorous Tetranychus magnoliae Tetranychus pacificus Pacific spider mite

1

Acari: Tetranychidae

314

A

B

C

D

E

A. Southern red mite. DAVID SHETLAR

B. Oak spider mites. DAVID SHETLAR

C. Honeylocust spider

mite male and female. WHITNEY CRANSHAW

D. Honeylocust spider

mites.

WHITNEY CRANSHAW

E. Leaf yellowing

produced by honeylocust spider mite. WHITNEY CRANSHAW

F

G

F. Overwintering

females of honeylocust spider mite. WHITNEY CRANSHAW

G. Maple spider mite. DAVID SHETLAR

H. Injury produced by ponderosa pine spider mite. WHITNEY CRANSHAW

I. Leaf injury produced

by maple spider mite. DAVID SHETLAR

H

I

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

SPIDER MITES

Clover Mite (Bryobia praetiosa)1 hosts A wide variety of herbaceous plants, including grasses, clover, and many weeds. Clover mites found on woody plants such as honeysuckle, ivy, elm, apple, and gooseberry are often considered subspecies or even different species. Damage Occasionally causes drying and death of turfgrass in spring, particularly in dry areas adjacent to buildings. However, problems are due primarily to the nuisance movement of clover mites into buildings, an extremely common occurrence during late winter and spring in much of North America. Distribution Throughout most of North America where cool winter conditions occur. Appearance Slightly larger than typical spider mite size and notable because it possesses very long front legs. Most are reddish or reddish green and the top of the abdomen is flattened. Silk is not produced by clover mites. Life History and Habits Clover mite is a cool-season species, most active in fall and spring. Most winter as eggs that may hatch during warm periods as early as February. They feed on plants, often producing meandering, silvery feeding tracks on the leaf surface. They may be full grown in a month or two depending on temperature. Adults migrate to nearby buildings, trees, and other upright surfaces to lay eggs. The most serious nuisance problems occur at this time as mites accidentally enter living areas. A second generation may occur or, most commonly, eggs remain dormant through summer and hatch with the return of cool weather in early autumn. A fall generation is then produced but receives less attention. Activity ceases with very cool temperatures, with most surviving this period as eggs. A few adults may persist through winter.

Related Species The brown mite (Bryobia rubrioculus) has a very similar appearance to clover mite but is associated with trees and shrubs. It is another cool-season species, active during late winter and spring when 2–3 generations may be produced. They feed on leaves and may cause some noticeable discoloration when numbers are high but are rarely considered serious pests. Winter is spent in the egg stage on the bark of host plants. Eggs are reddish, usually laid as masses on twigs but sometimes present on larger branches and trunks.

Other Turfgrass Mites Banks grass mite (Oligonychus pratensis)1 limits feeding to grass and is found primarily in western North America. It can be very damaging to Kentucky bluegrass suffering drought stress during late spring and early summer. Banks grass mite feeds on several types of grasses and is sometimes a pest of corn in the High Plains/Mountain States. A warm-season strain of this mite feeds on bermudagrass and St. Augustinegrass, where it can cause general yellowing of the leaves. Brown wheat mite (Petrobia latens)1 is primarily a pest of small grain crops in spring. It may occur in co-infestations with clover mite and Banks grass mite to damage turfgrasses in the western states during droughty conditions. Another cool-season mite found on turfgrass is winter grain mite (Panthaleus major).2 Eggs remain dormant throughout the warmer months and hatch as soil temperatures approach 50° F. This species may be active throughout the winter, feeding on grass blades during the night and clustering at the base of plants during the day. Outbreaks can kill grass in a manner often mistaken for winter kill. Winter grain mite is a bit larger than clover mite and brown wheat mite and possesses bright orange-red legs of uniform size.  Acari: Tetranychidae; 2 Acari: Eupodidae

1

316

A

B

D

E

C

F A. Clover mite injury to clover leaf.

G H

DAVID SHETLAR

B. Clover mite. DAVID SHETLAR

C. Clover mites caught on

sticky pad on windowsill. WHITNEY CRANSHAW

D. Clover mite injury to

turfgrass at base of home.

i

J

K

JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Clover mites and eggs. DAVID SHETLAR

F. Clover mites

on turfgrass.

WHITNEY CRANSHAW

G. Brown mite.

o

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

H. Brown mite eggs laid in rough area of tree bark. WHITNEY CRANSHAW

I. Brown wheat mite. FRANK PEAIRS, COLORADO STATE UNIVERSITY

L

J. Banks grass mites

aggregating for dispersal at tip of grass blade. WHITNEY CRANSHAW

K. Banks grass mites. FRANK PEAIRS, COLORADO STATE UNIVERSITY

L. Turfgrass damaged

by Banks grass mite. DAVID SHETLAR

M N

M. Sweet corn damaged by Banks grass mite. WHITNEY CRANSHAW

N. Winter grain mites. DAVID SHETLAR

O. Winter grain mites

on grass blades. DAVID SHETLAR

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

TARSONEMID MITES The tarsonemid mites (Tarsonemidae family)1 are extremely minute, often less than 1⁄80 inch. They are nearly colorless or may have a pale brown tint. Their life cycle differs in some details from that of spider mites, including the occurrence of a nonfeeding intermediate “pupal” stage that follows the larval stage. Development can be very rapid, with generation times completed in about 1 week.

Cyclamen Mite (Phytonemus pallidus)1 hosts A wide range including scores of herbaceous plants. African violet, delphinium, and strawberry are among the plants most commonly reported damaged. Damage Stunting or twisting of new leaves and flowers is the most commonly observed symptom. Leaves may look smaller and become more leathery than normal. Blackening and death of new growth, including flower abortion, may occur. Infested foliage often becomes infected with Botrytis fungal blight that can complicate diagnosis. Distribution Throughout North America. Appearance The pale yellow females are extremely small (slightly less than 1⁄100 inch) and require good magnification to be observed. Hind legs are reduced to threadlike structures. Life History and Habits Cyclamen mite can reproduce continually if temperature conditions are favorable. In areas of cold winter, it remains dormant and resumes activity in spring. Eggs are laid in small clusters in tight folds of young leaves and buds. An actively feeding larval stage may be completed in 3–4 days. The subsequent nonfeeding stage is usually completed in less than a week, after which adults are present. Females usually lay about 12–16 eggs over the course of a lifetime. Terminal growth is preferentially affected, and almost all activity occurs in protected sites of the plant such as unopened leaves of the crown, between tightly spaced young leaves, and in cuplike cavities of developing flower buds. Cyclamen mites feed on the upper leaf surface.

Related Species Broad mite (Polyphagotarsonemus latus)1 develops on leaves of a wide variety of plants, including begonia, impatiens, gerbera, ivy, dahlia, bean, schefflera, citrus, and pittosporum. It is restricted to greenhouses in temperate areas but occurs outdoors in warmer areas of the southern U.S. Broad mite is very similar in appearance to cyclamen mite and cannot be separated from it without high magnification. Unlike cyclamen mite, broad mite is almost always restricted to the underside of leaves and typically produces bronzing of foliage. Infestations of some plants may produce sudden stunting, twisting, and crinkling of young leaves, often followed by the appearance of blisters or sudden dieback. Flower abortion may also occur. On citrus, broad mite can cause russeting of the fruit surface. The life cycle of broad mite can be completed in less than a week during favorable summer conditions. Males are smaller and faster than females.

FALSE SPIDER MITES False spider mites (Tenuipalpidae family)2 have a flattened and somewhat elongate body. Most are orange to red and have short, stubby legs. Several species occur on plants, with those found on orchids and some trees and shrubs the most common. None produce silk. 318

A

B

C A. Cyclamen mites and eggs. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROJECT

B. Cyclamen mite injury to strawberry. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROJECT

C. Broad mite and eggs. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROJECT

D

D. Comparison of eggs produced by broad mite (left) and cyclamen mite (right).

E

RAYANNE LEHMAN, PENNSYLVANIA DEPARTMENT OF AGRICULTURE, BUGWOOD.ORG

E. Leaf twisting associated with

broad mite injury.

BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

F. Comparison of plant growth difference with control of broad mite on gerbera.

F H

CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SERVICE, BUGWOOD.ORG

G I

G. Injury to yew produced

J

by Pentamerisus taxi.

RAYANNE LEHMAN, PENNSYLVANIA DEPARTMENT OF AGRICULTURE, BUGWOOD.ORG

h. Brevipalpus sp. mite. RAYANNE LEHMAN

i. Phalaenopsis mites. DAVID SHETLAR

j. Injury produced by

phalaenopsis mites. DAVID SHETLAR

Pentamerismus erythreus2 is found throughout North America and occurs on most conifers except pine. P. taxi is an eastern species found primarily on Taxus. Both species can produce stippling and discoloration of foliage similar to that of spider mites, but injuries are considerably slower to develop. Privet mite (Brevipalpus obovatus)2 is foundGon several woody plants but most commonly on privet in the H southeastern states. An infestation can cause bronzing or reddening of foliage and premature leaf drop. Privet I foliage tends to turn yellowish bronze late in the summer as infestations are active from June through December. Brevipalpus oncidii and B. phoenicis are among the many mites associated with orchids. Other common orchidinfesting species include the “phalaenopsis mite” (Tenuipalus pacificus)2 and T. orchidarum. Feeding damage results in small silvery scars on the surface (usually underside) of leaves, with injured areas later turning brown.  Acari: Tarsonemidae; 2 Acari: Tenuipalpidae

1

319

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

RUST MITES Eriophyid mites (Acari: Eriophyidae, Phytopidae families) include an enormous number of species, the great majority undescribed, that develop on plants. Extremely minute in size, requiring considerable magnification to view (10–20× minimum), they are generally elongate or carrot-shaped in body form and have only two pairs of legs, which project forward. The majority are associated with foliage and most of these live on the leaf surface as “leaf vagrants.” The life cycle of the apple rust mite (Aculus schlectendali)1 is fairly typical of these leaf-inhabiting species. Winter is spent as a special adult female form (deutogyne) produced in fall that survives in cracks and crevices of twigs and buds. These females resume activity with bud break, feed on emerging leaves, and lay eggs on the leaf surface. Both males and summer-form females (protogynes) are produced at this time. Immature stages (two instars) resemble miniature adults, and a complete generation (from egg to egg-laying adult) can be completed in less than 2 weeks. Several generations are produced annually. In the case of the apple rust mite, populations peak in midsummer and decline as increasing numbers go into the dormant overwintering stage (deutogyne). In dry areas of very warm summer temperatures, peak numbers of apple rust mite may occur in early summer and fall. As eriophyid mite mouthparts are very small, feeding is limited to the epidermal cells, and the injuries caused by this feeding often result in no visible symptoms. For those species of eriophyid mites that cause leaf injury, the most common symptom is leaf bronzing or yellowing; mites that produce these injuries are known as rust mites or russet mites. Other symptoms that can be produced by leaf vagrant species may be increased thickening and/ or brittleness of foliage. A slight roll of the leaf edge is produced by others. The leaf-dwelling species include some also important in the transmission of some viruses that produce plant disease. Phyllocoptes fructiphilus is important as the primary vector of the virus that produces rose rosette. This disease has been devastating to some (not all) Rosa species, particularly multiflora rose (R. multiflora). Wheat curl mite (Eriophyes tosichella) is important in transmission of several viruses, particularly to grasses. Other eriophyid mites produce galls, distortions of growth on leaves (page 328), buds, or flowers (page 606). A

B

C

F

G

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

RUST MITES

SOME RUST MITES THAT PRODUCE BRONZING INJURIES TO FOLIAGE AND BUDS SCIENTIFIC NAME

COMMON NAME

HOST

Acalitus vaccinii Acaphylla steinwedeni1 Aculops cannibicola1 Aculops gleditsiae1 Aculops lycopersici1 Aculops massalongoi1 Aculops pelekassi1 Aculus fockeui1 Aculus ligustri1 Aculus schlechtendali1 Epitrimerus pyri1 Epitrimerus taxodii1 Nalepella halourga2 Nalepella octonema2 Nalepella tsugifoliae2 Paraphytoptus chrysanthemi1 Phyllocoptruta oleivora1 Setoptus strobacus2

Blueberry bud mite Orange camellia rust mite Hemp russet mite Honeylocust rust mite Tomato russet mite Lilac rust mite Pink citrus mite Plum rust mite/peach silver mite Privet rust mite Apple rust mite Pear rust mite Baldcypress rust mite Spruce rust mite Fir rust mite Hemlock rust mite Chrysanthemum rust mite Citrus rust mite White pine sheath mite

Highbush blueberry Japanese camellia Cannabis Honeylocust Tomato Lilac Citrus Cherry, plum, peach Privet Apple, crabapple, pear Pear Baldcypress Spruce Fraser fir Hemlock Chrysanthemum Citrus Eastern white pine

1

1

Acari: Eriophidae; 2 Acari: Phytoptidae

D

E

A. Rust mite injury to honeylocust. WHITNEY CRANSHAW

B. Wheat curl mites. DAVID SHETLAR

C. Symptoms of rose rosette disease,

produced by a virus transmitted by eriophyid mites. JENNIFER OLSON, OKLAHOMA STATE UNIVERSITY, BUGWOOD.ORG

D. Privet rust mite injury. DAVID SHETLAR.

E. Privet rust mites. DAVID SHETLAR

F. Hemlock rust mites.

H

I

DAVID SHETLAR

G. Injury symptom produced

by baldcypress rust mite. DAVID SHETLAR

H. Tomato russet mites. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROJECT

I. Hemp russet mites massed on cannabis. KARL HILLIG

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

GALL-MAKING APHIDS Although many species of aphids can curl developing leaves and needles, a few induce distinctive growth changes in plants substantial enough to be categorized as galls. Most of these aphids have complex life cycles that involve a primary winter host on which they produce galls and an alternate summer host. Petiolegall aphids (Pemphigus spp.)1 make a variety of galls on the stems, petioles, and leaves of cottonwood and poplar (Populus). Poplar petiolegall aphid (P. populitransversus) forms a spherical green gall with a transverse slit on the petiole of plains cottonwood; it is also a root aphid on cabbage family crops. Pemphigus populicaulis develops on eastern cottonwood, creating a gall that incorporates the lower edge of the leaf as well as the petiole. In summer it develops on the roots of various cabbage and aster family plants. Pemphigus betae develops on narrowleaf cottonwood or balsam poplar; summer forms occur on roots of plants in the family Chenopodiaceae. Sugarbeet root aphid (P. populivenae) forms an elongated gall on the midvein of narrow-leaved cottonwood leaves. Alternately, the summer forms feed on the roots of beet and related garden plants, and they are sometimes serious pests of beets and quinoa. Lettuce root aphid (P. bursarius) is an occasional pest of lettuce crops and also known from lambsquarter and carrot. It produces a flasklike gall on the petioles of Lombardy poplar. Poplar twiggall aphid (P. populiramulorum) is another species in this gallproducing genus. The presence of leaves deformed into a thickened, twisted, bladderlike mass is typical of the distortion produced by poplar vagabond aphid (Mordwilkoja vagabunda)1 on aspen and certain cottonwoods. Galls tend to remain on trees and may not be visible until after normal leaf fall. Galling is concentrated on the upper third of the tree. Winged stages leave the galls in summer, when they colonize a secondary host, presently unknown. Aphids return in late summer and early autumn to cottonwoods and aspen, at which time they lay overwintering eggs near buds and old galls. In the Pacific States, a common insect on manzanita is manzanita leafgall aphid (Tamalia coweni),1 which produces thickened leaf curls that discolor. Elm cockscomb gall aphid (Colopha ulmicola)1 creates elongate, wrinkled swellings on the upper surface of leaves of American and red elms. The galls are reddish when newly formed but turn brown later in the season. By early summer the aphids leave the galls through a slit that develops on the underside and fly to the roots of grasses, their summer hosts. Late in the season different winged forms return to elm, where they lay overwintering eggs around buds. Colopha graminis makes similar galls of elm leaves and also uses grasses as the alternate host. The elm-grass root aphid (Tetraneura ulmi)1 is an introduced species that produces reddish raised galls on the upper leaf surface of certain Asian elms. In summer it colonizes roots of grasses. Two interesting gall-making aphids are associated with witch-hazel. Witch-hazel leafgall aphid (Hormaphis hamamelidis)1 makes curious conical galls on the upper leaf surface. Birch is the alternate host for this insect. Spiny witch-hazel gall aphid (Hamamelistes spinosus)1 makes a spiny oblong gall from the buds of witch-hazel in spring. The life cycle of this insect can be very complex. Winged forms ultimately emerge from a slit at the base and subsequently develop on leaves of the alternate host, birch. It may be an important leaf curler of birch.  Hemiptera: Aphididae

1

322

A

B

C

D

G

H

E

F

i

J

K

L M

N

A. Poplar petiole gall on cottonwood.

F. Stem gall produced by poplar twiggall aphid.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

WHITNEY CRANSHAW

B. Interior of poplar petiole gall.

G. Aphids exposed within

L. Leaf gall produced by

JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Leaf gall likely produced

by the sugarbeet root aphid.

poplar twiggall.

witch-hazel leafgall aphid. DAVID SHETLAR

H. Poplar vagabond gall of aspen.

M. Distorted bud gall produced

WHITNEY CRANSHAW

JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Aphids exposed within

poplar vagabond gall.

WHITNEY CRANSHAW

JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Petiole gall on Lombardy poplar

J. Gall produced by elm

WHITNEY CRANSHAW

DAVID SHETLAR

produced by lettuce root aphid.

by a Tetraneura species of aphid.

WHITNEY CRANSHAW

D. Summer forms of sugarbeet

root aphid on roots of quinoa.

K. Leaf gall on elm produced

cockscomb gall aphid. 323

by spiny witch-hazel gall aphid. DAVID SHETLAR

N. Witch-hazel leaf gall aphid

on the leaves of the alternate birch host. JIM KALISCH, UNIVERSITY OF NEBRASKA

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

GALL-MAKING APHIDS

Grape Phylloxera (Daktulosphaira vitifoliae)1 hosts Grape. Damage On native grapes the most common injuries are small, rounded, spiky leaf galls that project from the leaves. These injuries are usually of negligible importance to plant health but can cause premature leaf drop. Leaf galls are produced only on North American grapes (Vitis riparia, V. labrusca, V. rupestris, others) or a few hybrids of North American grapes and European grapevine (V. vinifera). Greatest damage occurs when colonies develop on older roots. Dead areas develop around feeding sites, and knobby galls can develop that may girdle and kill the roots. North American grapes are resistant to damage by root feeding stages but they can be very injurious to European grapevine hybrids. European grape varieties in North America grown where grape phylloxera is present are usually grafted onto rootstock of resistant North American grape. Distribution Grape phylloxera is common and native in eastern North America where it is associated with native species of grapes that support the leaf gall forms. It has been introduced into several western grape growing regions where it occurs solely as root feeding stages that can be very damaging to susceptible rootstocks. Appearance Grape phylloxera appearing on roots are oval or pear-shaped and about 1⁄25 inch when full grown. Coloration varies from yellow to olive green to brown or orange. They have fairly similar form when encountered within leaf galls of grape. Life History and Habits In the eastern U.S. the life cycle can be complex, with both leaves and roots colonized. Winter is spent either as eggs under the bark of canes or as young nymphs on the roots, usually the former. Eggs hatch about the time of bud break, and the overwintered nymphs feed on the tips. Tissues swell about the developing grape phylloxera, producing a rounded gall on the underside of the leaf. After the nymphs mature, they may produce hundreds of eggs. The newly hatched crawlers disperse from the gall to tips and initiate new galls. Several generations may be produced in this manner. Some of the crawlers also colonize roots during summer. Roots are colonized by the insects working their way along soil cracks. Once they settle on roots, they can produce dense colonies that are a mixture of eggs, nymphs, and adults. Three to five generations may occur on the roots. At the end of the season, some work their way to the surface and produce winged forms and special sexual forms. The latter produce the overwintering eggs that are laid in crevices of the canes. In California and areas where native North American grapes are not present, only root-infesting forms survive winter, as young nymphs; winged forms, if they occur, are thought to be sterile.

Other Phylloxeran Leaf Gall Producers At least 29 species of Phylloxera cause galls on pecan and hickory (Carya spp.). Hickory leafstem gall phylloxera (P. caryaecaulis) produces rounded galls early in the season on shoots and petioles of hickory. Overwintering eggs laid near buds hatch around mid- to late April to produce a “stem mother” that feeds on the swelling bud. This causes the rounded gall to form, and eggs are laid by the stem mother in the gall. After egg hatch, the crawlers move to the leaf underside to feed and develop. A sexual generation follows that results in production of the overwintering eggs. Pecan leaf phylloxera (P. notabilis) and southern pecan leaf phylloxera (P. russellae) are among those that commonly produce galls on pecan leaves in the southeastern states. Pecan phylloxera (P. devastatrix) is the most damaging species to pecan, producing galls on leaves, woody shoots, and spurs. Damage is done by the first-generation stem mother, which emerges from eggs and feeds on the expanding buds in spring.  Hemiptera: Phylloxeridae

1

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A D B

C

E

F

G

A. Grape phylloxera leaf galls. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Grape phylloxera with

eggs exposed within leaf gall.

H

JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Close-up of grape

phylloxera on grape leaf. DAVID SHETLAR

D. Galls produced by hickory

leafstem gall phylloxera. DAVID SHETLAR

E. Hickory leafstem gall opened

to expose phylloxerans. DAVID SHETLAR

I

J

F. Gall produced by

pecan leaf phylloxera. LOUIS TEDDERS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

G. Gall opened to expose

pecan leaf phylloxera.

LOUIS TEDDERS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

H. Galls produced by pecan phylloxera. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

I. Pecan phylloxera bud gall opened to expose phylloxerans.

K

JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

J. Symptoms of oak phylloxera

on upper leaf surface. WHITNEY CRANSHAW

K. Oak phylloxera on

underside of bur oak leaf. WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

GALL-MAKING APHIDS

Hackberry Nipplegall Maker (Pachypsylla celtidismamma)1 hosts American and net-leaf hackberry. Damage Hackberry nipplegall maker produces prominent warty leaf galls, sometimes nearly covering the leaf. High levels of galling are usually restricted to only a few branches and do not produce much damage. This species is reported to be an important food for several insectivorous birds and for fox squirrels. Distribution Throughout North America in association with its host but more common east of the Rockies. Appearance Adults are a mottled light brown with wings held rooflike over the back. They jump and fly readily when disturbed. Immature stages, found in the gall, are pale yellow and of generally rounded form. Life History and Habits Hackberry nipplegall makers overwinter as adults in protected areas. In spring, as the hackberry buds are expanding, the adults emerge and deposit eggs on the undersurfaces of the leaves. Eggs hatch, and young nymphs begin to feed on the leaf. An overgrowth that appears as a raised swelling on the lower leaf surface is induced by this feeding, ultimately producing the gall that covers the insect. The nymphs develop singly within the gall all summer, and adults emerge in late summer. There is one generation per year. There can be a great difference in the number of galls produced on different leaves within the tree or between nearby trees. This difference is due largely to the degress of synchronization with leaf development when the adult psyllids are laying eggs and when eggs are hatching, since leaves are suitable hosts for only a brief period during their early development.

Other Gall-making Psyllids on Hackberry At least six Pachypsylla species produce galls on hackberry and sugarberry (Celtis spp.). Hackberry blistergall psyllid (P. celtidivescula) is often the most abundant psyllid associated with hackberry. Galls are small raised leaf swellings, much less conspicuous than the nipple galls. The life cycle of this species is similar to that of hackberry nipplegall maker. Blistergall psyllids are small enough to pass through most screens and sometimes enter nearby homes during fall and can be a nuisance. A similar gall, but with starlike projections on the leaf underside, is produced by hackberry stargall psyllid (P. celtidisastericus). Hackberry petiolegall psyllid (P. venusta) makes large irregularly round galls in the petioles of leaves, particularly in net-leaf hackberry. Hackberry budgall psyllid (P. celtidisgemma) produces an enlarged, spherical swelling in hackberry buds. Pachypslla celtidisinteneris develops in small, inconspicuous twig swellings.

326

A

B A. Hackberry nipplegalls on common hackberry.

C D

WHITNEY CRANSHAW

B. Nipplegalls produced on sugarberry. WHITNEY CRANSHAW

C. Hackberry nipplegall

maker and hackberry blistergall psyllids on newly emergent leaves. WHITNEY CRANSHAW

D. Hackberry nipplegall

maker psyllid. DAVID SHETLAR

E. Eggs laid by psyllids on

young hackberry leaves. WHITNEY CRANSHAW

F. Nymphs of hackberry

blistergall psyllid (below) and hackberry nipplegall maker (above) exposed from galls. WHITNEY CRANSHAW

E

G. Cast skins left behind

after adult emergence from hackberry blistergalls. WHITNEY CRANSHAW

H. Hackberry nipplegall maker psyllid nymph exposed within gall. WHITNEY CRANSHAW

F G H

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

GALL-MAKING APHIDS, AND ERIOPHYID MITES THAT PRODUCE LEAF OR BUD GALLS

Other Psyllids that Distort or Produce Galls on Foliage Yaupon psyllid (Gyropsylla ilicis)1 is a common species in the southern U.S., where it produces thickened leaf curls on yaupon (Ilex vomitoria). Willow hosts numerous psyllids of the genus Psylla, some of which produce small raised swellings on foliage. Cottony ash psyllid (Psyllopsis discrepans)1 develops on black ash and Manchurian ash and is present in areas of the Upper Midwest and Prairie Provinces where these hosts occur. Feeding by the nymphs on new leaves can cause leaf curling and puckering. The nymphs are covered with waxy threads and occur within leaf-fold pockets. Two generations are produced annually. Eugenia psyllid (Trioza eugeniae)2 induces small pits in new growth, which surround the scalelike nymphs. Reproduction can occur throughout the year, with peak activity during periods of new plant growth. Other Trioza species cause leaf-curling distortions. Redbay psyllid (T. magnoliae) is common in southeastern states, producing thickened leaf curls and galls on various species of Persea, particularly redbay (P. borbonia). Laurel psyllid (T. alacris) induces thickened curling of leaf margins on Grecian laurel and produces nuisance amounts of honeydew. It is currently found in parts of California and New Jersey. Peppertree psyllid (Calophya rubra)3 has become established in southern California and is a significant pest of California pepper tree. Feeding by the orangish nymphs on succulent foliage results in the formation of prominent pitting. Natural enemies have been established that have helped reduce the incidence of damage by this insect.  Hemiptera: Psyllidae; 2 Hemipera: Triozidae; 3 Hemiptera: Calyophyidae

1

ERIOPHYID MITES THAT PRODUCE LEAF OR BUD GALLS The activity of eriophyid mites most often attracts attention when they produce galls, abnormal plant growths of leaves, buds, and flowers. Slight curling of leaf edges is indicative of some species but others make more distinctive galls. Scabby blisters on leaf surfaces in which the mites develop are produced by the blistergall mites, whereas other species induce outgrowths of leaves in the form of small pouches (pouchgalls or bladdergall) or fingerlike projections (fingergalls or spindlegalls). Overstimulation of production of plant hairs resulting in feltlike patches known as erinea (sing., erineum) is a unique response of plants to feeding by certain eriophyid mites. Disorganized growths of buds or flower parts are also induced by infestation of some eriophyid mites (page 606).

328

B

C A. Symptoms of eugenia psyllid on upper leaf surface.

D

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

B. Galls produced by hackberry petiolegall psyllid. DAVID LEATHERMAN

C. Eugenia psyllid nymphs

on underside of leaf. WHITNEY CRANSHAW

D. Peppertree psyllids. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

A

E G

F E. Leaf symptoms produced by appleleaf blister mite. WHITNEY CRANSHAW

F. Leaf symptoms produced by pearleaf blister mite. HAROLD LARSEN, COLORADO STATE UNIVERSITY

G. Erineum produced by eriophyid mites on Rocky Mountain maple. WHITNEY CRANSHAW

H. Erineum produced by eriophyid mites on American cranberry

bush.

JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Leaf symptoms produced by walnut blister mite. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

H

I

B C

A D

E

F

G

H

I

J K

L M

N A. Erineum produced by eriophyid mites on American beech. DAVID SHETLAR

WHITNEY CRANSHAW

H. Spindlegalls on linden. DAVID SHETLAR

B. Pouchgall symptom on

I. Fingergalls on chokecherry.

WHITNEY CRANSHAW

J. Fingergalls on American

upper leaf surface of boxelder. C. Erineum within

pouchgall on lower surface of boxelder leaf. WHITNEY CRANSHAW

D. Maple bladdergalls. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Eriophyid mites within

maple bladdergall.

JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Pouchgalls on willow. WHITNEY CRANSHAW

O P

G. Pouchgalls on alder.

WHITNEY CRANSHAW

plum.

WHITNEY CRANSHAW

K. Leaf curl along edge

of aspen produced by eriophyid mites. WHITNEY CRANSHAW

L. Fingergalls on

sugar maple. DAVID SHETLAR

M. Distortion of pine

growth by eriophyid mites. WHITNEY CRANSHAW

N. Leaf curl distortion

produced by fuchsia gall mite.

JACK KELLY CLARK, COURTESTY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

O. Leaf curl of cannabis leaf produced by hemp russet mite. KARL HILLIG

P. Distortion of blue spruce

produced by eriophyid mites. WHITNEY CRANSHAW

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

ERIOPHYID MITES THAT PRODUCE LEAF OR BUD GALLS

SOME COMMON ERIOPHYID MITES THAT PRODUCE DISTORTIONS AND GALLS ON LEAVES SCIENTIFIC NAME1

COMMON NAME (IF PROPOSED) HOST

BLISTER MITES2 Eriophyes pyri

Pearleaf blister mite

Pear

Eriophyes mali

Appleleaf blister mite

Apple, crabapple

Eriophyes sorbi Aceria erineus

Mountain-ash Walnut blister mite

English walnut

Aceria caryae

Pecan leafroll mite

Pecan

Aceria malherbae

Bindweed mite

Field bindweed

Aculops cannibicola

Hemp russet mite

Cannabis

Aculus lobulifera

Cottonwood leafcurl mite

Eastern cottonwood

Aculops fuchsiae

Fuchsia gall mite

Fuchsia

Eriophyes tosichella

Wheat curl mite

Many grasses

LEAF-CURLING SPECIES

POUCHGALL/BLADDERGALL SPECIES

2

Vasates quadripedes

Maple bladdergall mite

Maple

Aceria negundi

Boxelder erineum mite

Boxelder

Aceria chrondriphora Aceria baccharices

Ash Baccharis gall mite

Coyote bush

Eriophyes ulmi

American elm

Phyllocoptes didelphis

Aspen

Phyllocoptes populi

Aspen, black poplar

Aculops tetanothrix complex

Willow

Aculops toxicophagus

Rhus

Phytoptus laevis

Alder beadgall mite

Alder

FINGERGALL/SPINDLEGALL SPECIES Vasates aceriscrumena

Maple spindlegall mite

Sugar and silver maples

Eriophyes emarginatae

Plum, chokecherry, bitter cherry

Eriophyes cerasicrumena

Black cherry

Eriophyes tiliae Aceria parulmi

Basswood, linden Elm eriophyid mite

American elm

332

INSECTS AND MITES THAT SUCK FLUIDS FROM LEAVES AND NEEDLES

ERIOPHYID MITES THAT PRODUCE LEAF OR BUD GALLS

SCIENTIFIC NAME1

COMMON NAME (IF PROPOSED) HOST

ERINEUM PRODUCERS Acalitus fagerinea

American beech

Aceria aceris

Silver maple

Aceria modestus

Maple

Aceria elongatus

Sugar maple

Aceria varia

Aspen

Aceria caulis

Black walnut petiolegall mite

Black walnut

Colomerus vitis

Grape erineum mite

Grape

Eriophyes calceris

Western erineum maple mite

Rocky Mountain maple

Acalitus vaccinii

Blueberry bud mite

Blueberry, huckleberry

Aceria parapopuli

Poplar budgall mite

Cottonwood, poplar

Aceria aloinis

Aloe mite

Aloe, Haworthia

BUDGALL SPECIES

Cecidophyopsis vermiformis

Filbert

Cecidophyopsis psilaspis

Taxus bud mite

Yew

Cecidophyopsis ribis

Currant bud mite

Black currant

Ceciophyes betulae

Birch

Eriophyes sheldoni

Citrus bud mite

Citrus

Phytocoptella avellanae

Filbert bud mite

Filbert, hazelnut

Trisetacus pini

Pine bud mite

Pines

Trisetacus cupressi

Southern redcedar

Trisetacus campnodus

Pine

Trisetacus gemmavitians Trisetacus juniperinus

Scotch pine Juniper tip dwarf mite

Juniper

Trisetacus thujivagrans

Arborvitae

WITCHES’-BROOMING SPECIES Eriophyes celtis

Hackberry witches’-broom mite

Hackberry

Eriophyes cynodoniensis

Bermudagrass mite

Bermudagrass

Eriophyes slykhuisi

Buffalograss mite

Buffalograss

Eriophyes zoysiae

Zoysiagrass mite

Zoysiagrass

1

Acari: Eriophyoidea

2

Many pouchgalls and blistergalls intergrade with other forms, including several where erinea are also produced.

333

CHAPTER FOUR

INSECTS ASSOCIATED WITH STEMS, TWIGS, SHOOTS, AND CANES

EUROPEAN PINE SHOOT MOTH

(Rhyacionia buoliana)1

hosts Red, mugho, Scotch, Austrian, and some other hard pines Damage The young larvae kill small buds, which is soon noticed when the buds do not expand in the spring. During spring feeding, the larvae enter and kill larger expanding shoots, causing them to wilt and soon turn brown. If all the leader buds are attacked, a lateral curls around to take its place, forming a permanent crook or “post horn.” Heavy infestations result in rounded trees with very stunted growth. Distribution European pine shoot moth is common over most of the northern U.S. and southern Canada. Appearance The adults and larvae of this pest are usually not seen but their damage, in the form of wilting or dead shoots, is very noticeable. Adults are generally rust-colored moths, about ⅜ inch long. The larvae and pupae, which are pale reddish brown, are found within damaged terminals. Life History and Habits One generation is produced annually. The overwintering stage is a partially grown caterpillar that hibernates in a silk-lined cavity chewed into pine buds. In late April, when the pine shoots begin to expand, the larvae resume their habit of boring into shoots. The larvae may move from one shoot to another, usually entering at the base. The entrance holes are covered with silk webbing coated with pine pitch. The larvae finish development at the end of May and soon form a pupal cell within one of the tunneled shoots. The adult moths emerge 2–3 weeks later. Mating occurs on the pines, and females soon lay eggs on needle bases, bark, and bud scales. The eggs hatch in 7–10 days and the tiny caterpillars burrow into needle bases. By August, the young larvae move to the newly formed buds. Here they burrow into a bud and construct a resin-coated web over the entrance hole. By the end of August, the larvae cease activity, remaining dormant until the next spring.

Other Moths that Develop in Shoots and Terminal Growth of Conifers Approximately 22 Rhyacionia species occur in North America, all associated with terminal growth of pines. Nantucket pine tip moth (Rhyacionia frustrana) attacks most two- and three-needle pines. The overwintering stage is a pupa present within previously damaged terminals. It transforms to the adult form in early spring, and females lay eggs on shoots and needles, with egg-laying synchronized with the emergence of new growth. Eggs hatch in about 2 weeks, after which the young larvae mine needles, shoots, and buds. As they get older, they feed inside new buds and shoots. A small tent of silk covered with plant resin may be present at the site of injury. First symptoms of injury include some browning and dying of a few needles at the tips of branches, progressing to terminal dieback. Trees under 15 feet and growing in open sites are most severely attacked. These larvae mature, pupate, and produce a second generation, with adults present 5–6 weeks after the firstgeneration adults. In warmer areas, a third generation of moths may be active and lay eggs in August. Occasionally even a fourth generation is reported. Nantucket pine tip moth is present from New England to Florida, west to New Mexico and Arkansas, and has been found in southern California. 334

A

B

C

D E

A. Symptoms of European pine tip moth injury. DAVID SHETLAR

B. European pine tip moth larva

exposed from damaged terminal. DAVID SHETLAR

C. European pine tip moth pupal

case exposed from damaged terminal. DAVID SHETLAR

D. European pine tip moth. DAVID SHETLAR

E. Symptoms produced from

repeated injuries by Nantucket pine tip moth. TERRY S. PRICE, GEORGIA FORESTRY COMMISSION, BUGWOOD.ORG

F. Nantucket pine tip moth. USDA FOREST SERVICE, BUGWOOD.ORG

G. Evidence of needlemining

produced by early-instar larvae of Nantucket pine tip moth. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

F

G

H. Terminal injuries typical of Nantucket pine tip moth. ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

I. Nantucket pine tip moth exposed from terminal. DARRELL ROSS, OREGON STATE UNIVERSITY, BUGWOOD.ORG

J. Extensive tunneling produced

by larvae of Rhyacionia zozona.

DONALD OWEN, CALIFORNIA DEPARTMENT OF FORESTRY AND FIRE PROTECTION, BUGWOOD.ORG

H

I

J

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

MOTHS THAT DEVELOP IN SHOOTS AND TERMINAL GROWTH OF CONIFERS Southwestern pine tip moth (R. neomexicana) is found in the High Plains and Rocky Mountain region. Austrian, ponderosa, and mugho pines are common hosts. Winter is spent in cocoons plastered to the base of trees, and adults emerge about the time new growth is emerging. Western pine tip moth (R. bushnelli) develops primarily on ponderosa pine but damages other pines, including Monterey pine since introduction of the insect into California. The species now occurs throughout most of the U.S. west of the Dakotas. One generation per year occurs in the northern area of the range, but two generations are reported from Nebraska, with flights in April–May and again in late June–July. Damage to ponderosa pine can be severe in areas with two generations. Rhyacionia zozana is another species associated with ponderosa pine in California. Pinyon grown in Colorado and the southwestern U.S. is frequently damaged by pinyon tip moth (Dioryctria albovittella).1 The overwintering stage is a firstinstar larva on the bark that resumes feeding in spring and enters unopened buds. Tunneling later extends into the pith of terminals, resulting in girdling wounds that Symptoms produced by cause terminals to die and break by mid-July. Cones are also sometimes tunneled. Related a branch attack by the pinyon pitch mass borer. species that occur in branches of native pines in the High Plains and Rocky Mountain WHITNEY CRANSHAW states include D. ponderosae (pinyon pitch mass borer) and D. cambiicola. Pinyon pitch nodulemaker (Retinia arizonensis)1 is a common tip moth in native pinyon stands but often uncommon in cultivated plantings. It produces a large, characteristic purplish nodule, in which the larva can be found, at the wound site. Adults emerge in midsummer to lay eggs, and larvae initiate tunneling before fall dormancy. Ponderosa pine tip moth (R. metallica) attacks terminal growth Injury produced by of ponderosa pine in Nebraska, Colorado, and New Mexico. Although pitch forms at juniper twig girdler. wounds, the large purplish pitch nodule does not form. Northern pitch twig JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM moth (R. albicapitana)1 is found throughout Canada. Jack pine is its preferred host, although it is also found on Scotch, mugho, red, and lodgepole pines. Development is extended, requiring 2 years to complete. Pitch twig moth (R. comstockiana) can be a common insect tunneling into young branches of pines in the midwestern and northeastern states. Large masses of pitch typically develop at wound sites. Several Eucosma species are associated with pines in North America, many developing as borers of cones. In the western states, western pine shoot borer (E. sonomana) tunnels terminal growth of ponderosa and lodgepole pine. Injuries produce stunting of infested terminals. In northeastern North America, the eastern pine shoot borer (Eucopina gloriola)1 hollows out 6- to 8-inch tunnels in shoots, which then wilt and drop from the plant. White and Scotch pine are most commonly damaged. Juniper twig girdler (Periploca nigra)2 damages juniper, particularly Tam juniper, in the western U.S. Larvae are cream-colored with a dark head and tunnel the twigs, causing them to die and conspicuously flag. Juniper twig girdler is common in parts of California, where it limits use of Tam juniper in landscapes. Tip dieback on arborvitae and cypress can also occur by the tunneling of cypress tipminer (Argyresthia cupressella).3  Lepidoptera: Tortricidae; 2 Lepidoptera: Cosmopterigidae; 3 Lepidoptera: Argyresthiidae;

1

336

A

B

D

E

F

C

G

A. Injury to mugho pine produced by southwestern pine tip moth. WHITNEY CRANSHAW

H

I

B. Larva of the pinyon tip moth in a pinyon terminal. WHITNEY CRANSHAW

C. Pinyon pitch mass borer

exposed from pitch mass. WHITNEY CRANSHAW

D. Symptoms of infestation

by pinyon pitch nodule maker. DAVID LEATHERMAN

E. Larva of pitch twig moth in twig. DAVID SHETLAR

F. Injury symptom produced by pitch twig moth.

J

DAVID SHETLAR

G. Adult pitch twig moth. DAVID SHETLAR

H. Damage produced by

western pine shoot borer.

K

DARRELL ROSS, OREGON STATE UNIVERSITY, BUGWOOD.ORG

I. Larva of western pine shoot borer. DARRELL ROSS, OREGON STATE UNIVERSITY, BUGWOOD.ORG

J. Injury produced by cypress

tip moth.

ROBIN ROSETTA, OREGON STATE UNIVERSITY

K. Larvae of the cypress tip moth. ROBIN ROSETTA, OREGON STATE UNIVERSITY

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

WHITE PINE WEEVIL

(Pissodes strobi)1

hosts White pine and spruce are primary hosts in eastern North America; spruce in the western areas. Damage Larvae tunnel underneath the bark of the terminal. Girdling wounds cause the leader to suddenly wilt and die in early summer, producing a curling known as a “shepherd’s crook.” Once the top leader is killed, some side branches change their growth habit and begin to grow upward to take the place of the killed leader. If successful, these new leaders form main trunks, and multiple main trunks occur above the damaged area. This changes the form of the tree from its normal tapering growth to one that is more densely bushy with multiple leaders. Appearance Adults are small (ca. ¼ inch) snout beetles flecked with brown and white patches. Larvae are legless grubs found under the bark and are white with a brown head. Distribution Widespread in the northern U.S. and southern Canada. Life History and Habits The insect overwinters in the adult stage, under leaf litter and in other protected areas. On warm, sunny afternoons in late spring, the weevils become active and crawl or fly to host trees. Adult feeding occurs on the cambium of main branches near the leader, and later the females insert eggs into some of the feeding cavities. Small points of oozing pitch present on the main leader are indicators of this feeding and egglaying activity. Eggs hatch in 1–2 weeks, and the young legless grubs (larvae) tunnel downward underneath the bark. Damage increases as the insects grow—they feed for about 4–6 weeks—and wilting starts to become noticeable in June and July. When full grown, the larvae tunnel deeper into the stem and form a cocoon made of wood chips in which they pupate. In about 2 weeks, the adult beetles emerge through small holes chewed through the bark. The chip cocoons remain behind and are a useful means of diagnosing old white pine weevil injury. Adult weevils feed on the needles, buds, and twigs of pine or spruce for several weeks before going into a dormant condition for overwintering. Some minor chewing injury to buds may result if infestations are severe.

Other Beetles that Develop in Shoots and Terminal Growth of Conifers Eastern pine weevil (Pissodes nemorensis), also known as deodar weevil, occurs in the southern states and damages true cedars (Cedrus) and some pines. Adults are often most damaging, causing branch tips and small branches to be killed by feeding punctures. Larvae develop under the bark and may girdle branches. Northern pine weevil (P. approximatus) is nearly identical and sometimes considered the same species. It has a northern distribution, and larvae develop in stumps and trunks of recently killed trees. Eggs are usually laid singly rather than in groups, often at the base of trees. Summer adults can feed on small branches and girdle them, especially where abundant amounts of freshly cut stumps allow numbers to increase. Adult damage to pine twigs is the primary damage produced by pales weevil (Hylobius pales)1 in the Midwest. This species chews small punctures in the twigs, and crystalized resin collects along the surface. These injuries often girdle the plant, causing small branches to die back. Damage is particularly important to seedlings, which can be killed. Pales weevils lay eggs in stumps of recently killed or cut conifer trees in spring, and larvae mature by midsummer. Peak adult feeding occurs at this time. The presence of suitable cut stumps for larval development, as is found in Christmas tree farms, determines local importance of pales weevil. White, pitch, loblolly, shortleaf pines, and Douglas-fir are particularly favored, but juniper and other conifers may be damaged. 338

A D

E

B

C A. White pine weevil injury

F

symptoms on blue spruce. WHITNEY CRANSHAW

B. White pine weevil. DAVID SHETLAR

C. White pine weevil

larvae exposed from damage pine leader. DAVID SHETLAR

D. Chip cocoons

produced by pupating white pine weevils. DAVID LEATHERMAN

E. Mating pair of white

pine weevils on terminal. DAN HERMS, THE OHIO STATE UNIVERSITY

F. White pine weevil injury

to a row of white pine. DAVID SHETLAR

G. White pine weevil adult

emerging from chip cocoon. DAVID SHETLAR

H. Tip dieback/flagging

caused by feeding injuries of pales weevil. ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

I. Pales weevil adults. ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

J. Pales weevil adult.

G H

DAVID SHETLAR

I

J

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

BEETLES THAT DEVELOP IN SHOOTS AND TERMINAL GROWTH OF CONIFERS Adult feeding is often the most commonly observed damage by pitcheating weevil (Pachylobius picivorus).1 Adults lay eggs in the soil around newly cut or dying pines, and the larvae develop on the roots. At night the adults fly to adjacent pines and feed on the inner bark of twigs, causing twig dieback. Larval damage to seedling trees occurs when new plantings occur near cut trees. The genus Magdalis,1 represented by 24 species in North America, develop in small, recently dead or dying branches of stressed pine, elm, hickory, and willow. Most species are associated with pines, and the adults are typically about 1⁄5 inch and bluish black. Magdalis weevils cause little plant injury. Adults puncture the sheath area of needles when they feed in midsummer, which may then dry up and break from the plant. Larvae tunnel into the ends of branches that may subsequently break off. Winter is spent in the larval stage, within tunnels made in dead twigs and branches. In spring they pupate, and late in May and June the adults cut their way to the surface, producing a small round exit hole. Adults feed throughout summer and females lay eggs in small pits they chew in twigs. Cedar bark beetles (Phloeosinus spp.)1 develop in juniper, arborvitae, cypress, and cedar. Adults feed on small leaflets and may girdle small twigs, typically several inches back from the tip, causing flagging. Most damage is done as the developing larvae feed under the bark. If only certain branches are killed, this results in conspicuous flagging. Entire trees may be killed, particularly if there is a preexisting stress due to root rot or other injury, which greatly increases susceptibility to these insects. Approximately two dozen Phloeosinus species are known from North America, all of which develop in conifers and most of which occur west of the Mississippi River . The gallery system made by cedar bark beetles has a central tunnel running parallel to the branch or trunk, with numerous side tunnels going off at right angles. The galleries are usually free of extensive sawdust. Larvae are minute, legless white grubs, found in their tunnels during active infestations. The adults are ⅛ inch long, reddish brown to black shiny beetles of typical oblong bark beetle form. The wing covers are marked by lengthwise rows of minute puncture marks. Common pine shoot beetle (Tomicus piniperda)1 damages shoots of pine (Scotch, Austrian, eastern white, red, and jack) while in the adult stage. Adults fly to the crowns of living trees and initiate “maturation feeding.” This involves boring into lateral shoots which are hollowed 1–4 inches and subsequently wilt and die. The larvae develop under the bark in the stump and complete development in May or early June. Most twig beetles (Pityophthorus spp., Pityogenes spp.)1 develop in pine, spruce, true firs, and/or Douglasfir. Larvae of all tunnel the inner bark, and their girdling injuries can produce flagging of terminal growth. These beetles are usually secondary pests, breeding in dying wood, and can be indicative of substantial stress on the plant. In natural situations, twig beetles function as pruners of shaded-out or broken twigs and branches. In urban settings, they are usually observed as contributors to the death of recently transplanted or stressed pines. Adults are tiny bark beetles, 1⁄32–1⁄6 inch long, generally dark brown. Most species have rounded rear ends, but some male Pityogenes have a pair of curved, fingerlike projections. Larvae are small, legless, C-shaped grubs with a caramelcolored head and are found within the twigs. Adult emergence, flight, and tunneling into twigs for egg laying occur throughout the warm months and may begin by mid-March following mild winters. The adults find suitable hosts, tunnel under the bark, and produce eggs along a gallery they excavate. These attacks produce much tan or reddish sawdust but little pitch. The galleries made beneath the bark by adults and feeding larvae are generally star-shaped and lightly etch the wood. Most species of twig beetles have 2–4 generations per year. 1

Coleoptera: Curculionidae (Scolytinae)

340

A

B

D

E

C A. Pitch-eating weevil. ROBERT L. ANDERSON, USDA FOREST SERVICE, BUGWOOD.ORG

B. A Magdalis species. DAVID LEATHERMAN

C. Tunneling of terminal

by cedar bark beetle adult. WHITNEY CRANSHAW

D. Tip dieback caused by

wounds produced by adult cedar bark beetle. WHITNEY CRANSHAW

E. Cedar bark beetle adult

in tunnel.

JIM KALISCH, UNIVERSITY OF NEBRASKA

F

F. Egg gallery and larval tunnels produced by cedar bark beetles in juniper trunk.

G

WILLIAM M. CIESLA, FOREST HEALTH MANAGEMENT INTERNATIONAL, BUGWOOD.ORG

G. Exit hole produced by

common pine shoot beetle. DAVID SHETLAR

H. Common pine shoot

beetle adult in tunneled twig. DAVID SHETLAR

I. Adult of the chestnut

brown bark beetle, Pityogenes hopkinsi.

J. R. BAKER & S. B. BAMBARA, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

J. Galleries produced by

Pityogenes hopkinsi on white pine.

TIM TIGNER, VIRGINIA DEPARTMENT OF FORESTRY, BUGWOOD.ORG

K. A Pityophthorus species

of bark beetle.

BOB PARKS, MUSEUM COLLECTIONS: COLEOPTERA, USDA-APHIS ITP, BUGWOOD.ORG

L. Galleries produced by

H J

K

Pityphthorus twig beetles.

I

DAVID LEATHERMAN

L

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

FLIES THAT DEVELOP IN SHOOTS AND TWIGS OF CONIFERS Pitch midges1 develop in pits excavated in new twigs of pine and live in the exuded resin masses. Gouty pitch midge (Cecidomyia resinicola) causes swellings and malformation of terminals and death of needles. Larvae are usually gregarious and found in the resin patches at wounds. C. piniinopis is often more damaging and occurs throughout the northern U.S. and southern Canada. Larvae develop in pits near the tips of various pines. Multiple injuries often cause girdling that causes tufts of needles to die. Winter is spent as a larva in the shoots, and pupation occurs at the base of nearby needles in spring. Multiple generations may be produced. Terminals of white spruce may be distorted by the spruce gall midge (Dasineura piceae).1 Adults lay eggs in spring on the new buds and the larvae subsequently move to the base of developing needles, producing a swollen chamber at the base of the needles. Heavily infested terminals become distorted and may die back. Twig dieback of juniper grown in the Midwest can be produced by juniper midge (Contarinia juniperina).1 Larvae tunnel into the twigs at the base of needles and produce girdling wounds that cause dieback often mistaken for fungal twig blights produced by Phomopsis or Kabatina. Damage begins in spring as larvae overwintering in the twigs resume feeding, and several generations may be completed annually. Junipers most commonly damaged include Andorra, blue rug, and Juniperus chinensis. 1

Diptera: Cecidomyiidae

MOTHS THAT DEVELOP IN SHOOTS, TWIGS, AND CANES OF DECIDUOUS TREES AND SHRUBS Cottonwood twig borer (Gypsonoma haimbachiana)1 tunnels into new shoots of cottonwood, causing tips to break. Branches of chronically infested trees develop a tufted appearance, and the dropped twigs may become a significant nuisance. The larvae are dirty gray caterpillars with a brown head and may be found associated with tunneled twigs. The overwintering stage is a very young larva found in small pits in the bark, often near old leaf scars or tunneling wounds. Larvae resume activity in spring, boring into actively growing shoots and tunneling down the pith. When full grown (late May–early June), they emerge and crawl down the trunk, pupating in protected sites on trunks and branches. Adults emerge in about 8–10 days, and females typically lay eggs on the upper leaf surface. The young larvae first feed on the midrib or vein of leaves. Later they migrate to and tunnel twigs. Boxelder twig borer (Proteoteras willingana)1 can be commonly associated with boxelder maple in parts of the central U.S. and Prairie provinces. Eggs are laid on leaves in midsummer, and the larvae feed on leaves until September. They subsequently bore into dormant buds, where they spend the winter. In early spring they resume feeding and may damage several additional buds before they tunnel into a new shoot. In much of the same range, boxelder may also host P. crescentana, and boxelders in the southwestern states host P. arizonae. The maple twig borer (P. aesculana) produces similar injuries to twigs of silver maple, and P. moffati tunnels buds of sugar maple. In the southeastern U.S., Episimus tyrius can cause flagging of new growth of red maple. 342

B

C A D E A. Pitch midge larvae and injury to ponderosa pine. WHITNEY CRANSHAW

B. Pitch midge larvae. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Dieback produced by gouty

pitch midge feeding injuries.

DONALD OWEN, CALIFORNIA DEPARTMENT OF FORESTRY AND FIRE PROTECTION, BUGWOOD.ORG

D. Pupal cocoons produced by pitch midge. WHITNEY CRANSHAW

E. Adult pitch midge. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G. Juniper midge larva in tip of juniper. DAVID SHETLAR

F. Injury symptoms produced

F H

by spruce gall midge.

STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

I

G H. Larva of cottonwood twig borer in cottonwood twig. WHITNEY CRANSHAW

I. Symptoms of injury produced by maple shoot borer. DAVID SHETLAR

J. Leaf drop associated with

infestation of maple shoot borer. DAVID SHETLAR

K. Larva of maple shoot borer. DAVID SHETLAR

J

L. Exit hole produced by

boxelder twig borer. WHITNEY CRANSHAW

L

K

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

MOTHS THAT DEVELOP IN SHOOTS, TWIGS, AND CANES OF DECIDUOUS TREES AND SHRUBS Several other caterpillars develop as twig borers of other forest trees. Twigs of black locust may be tunneled by locust twig borer (Ecdytolopha insiticiana),1 Epinotia solicitana1 develops in shoots of white and gray birch; E. nisella develops in small branches of balsam poplar. Similar twig injuries to fruit trees are produced by caterpillars of the Oriental fruit moth (Grapholita molesta).1 Adults are active in early spring and first begin to lay eggs around the time of apple bloom. Eggs are laid on leaves; upon hatching, the larvae enter the twigs at the base of the leaf then tunnel to the base of the shoot. Damaged terminals wilt and die back beyond the point of injury. Mature larvae may be found within wilting terminals and are dirty-white or pinkish with a reddish-brown head. Larvae may injure more than one terminal or enter and feed within fruit. Between 3 and 5 generations are produced annually. In the eastern half of the U.S., the cherry fruitworm (G. packardi)1 tunnels the shoots of many rosaceous hosts, particularly cherry, apple, and hawthorn. Peach twig borer (Anarsia lineatella)2 develops in shoots and fruit of various stone fruit (Prunus spp.) trees and is particularly damaging to peach. Winter is spent as a partially grown caterpillar, protected in a small silkcovered cell on the bark of fruit trees. In early spring, the caterpillars become active, migrate to the twigs, and tunnel the buds and emerging terminal growth. The damaged new growth, often referred to as a “shoot strike,” typically wilts and dies beyond the point of injury. The caterpillars then pupate in the tree and usually emerge as small grayish moths in May. Later generations continue to mine terminals, and some may feed on fruit after the pit has begun to harden. The most common insect affecting terminal growth of black walnut is walnut shoot moth (Acrobasis demotella).3 In early summer, moths are active and females lay eggs on the underside of leaves of walnut, hickory, and pecan. The larvae feed on the leaves for a brief period and then move to the twigs, where they spin a silken cover (hibernaculum) for winter. In spring, as buds begin to swell, they resume activity and tunnel buds. They later enter the expanding twigs, which kills the shoots. Elder shoot borer (Achatodes zeae)4 develops within canes of elder (Sambucus), particularly golden elder, causing canes to die back in spring. The elder shoot borer spends the winter in the egg stage, within an egg mass attached to bark of the old canes. Eggs hatch about the time that the new shoots start to emerge, typically late April. The young larvae first feed on the unfolding leaves for several days before boring into the new shoots. Caterpillars feed and develop for about 6–8 weeks, pupating in late June or early July. Pupation may occur within the damaged shoot, but often occurs in the pithy center of dead, dry branches, or on the ground. Adults emerge in July, when females lay eggs in small masses under loose bark of old canes. The currant borer (Synanthedon tipuliformis)5 develops in the canes of currants and gooseberries and can be found throughout North America in association with these hosts. Although most feeding is confined to the pith, it also does feed some on woody tissues, and injuries may cause canes to break. The currant borer spends winter within the cane, usually near the soil line. After a brief period of feeding in spring, they prepare an exit hole that is covered by either a very thin layer of bark or a bit of silk. After two to three weeks, adults emerge to mate, often on the leaves of their host plant, and the females then begin to lay eggs. Eggs are laid near buds and the larvae enter the plant where they feed throughout summer and early fall. Larvae of other clearwing borer moths develop in small branches and canes of trees and shrubs, including viburnum borer (Synanthedon viburni),5 rhododendron borer (S. rhododendri), and at least four Synanthedon species associated with willow. Lilac-ash borer (Podosesia syringae)5 can develop in the stems of lilac as well as branches and also the trunks of ash.  Lepidoptera: Tortricidae; 2 Lepidoptera: Gelechiidae; 3 Lepidoptera: Pyralidae; 4 Lepidoptera: Noctuidae; 5 Lepidoptera: Sesiidae

1

344

A. Larva of locust twig borer in black locust twig. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

B. Shoot dieback in peach produced by Oriental fruit moth. DAVID SHETLAR

B

C. Shoot tunneling

by peach twig borer larva. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Injury symptom produced by walnut shoot moth. ROBERT L. ANDERSON, USDA FOREST SERVICE, BUGWOOD.ORG

E. Larva of walnut

A

C

D

shoot moth.

USDA FOREST SERVICE– NORTHEASTERN AREA, BUGWOOD.ORG

F. Currant borer larva in currant cane. WHITNEY CRANSHAW

G. Adult currant

borer.

WHITNEY CRANSHAW

H. Cane breakage

due to currant borer injury.

WHITNEY CRANSHAW

I. Lilac-ash borer larva

E

overwintering in stem.

F

DAVID SHETLAR

G H

I

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

ROSE SHOOT SAWFLY

(Hartigia trimaculata)1

RASPBERRY HORNTAIL

(Hartigia cressoni)1

hosts Rose, raspberry, blackberry, boysenberry. Damage Larvae tunnel the upper half of canes, causing wilting and often breakage beyond the point of injury. Distribution Rose shoot sawfly is widely distributed across North America east of the Rocky Mountains. Raspberry horntail is a western species found from California east to parts of Colorado and Montana. Appearance Adults, rarely observed, are elongate, ½-inch, black-and-yellow stingless wasps. The creamcolored larvae are found in the plant and have a distinct pale head capsule, distinguishing them from other borers found in canes. Life History and Habits Winter is spent as a full-grown larva in the old canes. The larvae pupate in spring, and adults emerge in April and May. Females insert eggs into succulent tissues at the tip of current-season growth. Upon hatching, the larvae enter the stem to feed, producing a spiraling girdle. Older larvae feed in the pith and are occasionally found in larger roots. Pupation occurs in the stem, and some pupae often transform to the adult stage and produce a second generation.

Other Sawfly Shoot and Stem Borers Viburnum stem sawfly (Janus bimaculatus)1 develops in the terminal growth of various viburnums, including Viburnum lentago (nannyberry) and V. prunifolium (blackhaw). Related species include the willow shoot sawfly (J. abbreviatus) that develops in the tips of cottonwoods and willow and J. quercusae and J. rufiventris in oak twigs. Maple petiole borer (Caulocampus acericaulis)2 is a common insect associated with sugar maple in much of the eastern U.S. Larvae burrow into leaf petioles, which subsequently break near the blade. This produces a noticeable shedding of leaves in late May and early June. Larvae remain in the petiole stump, but eventually emerge to pupate in the soil and have one generation per year, with adults laying eggs in late April and May. Curled rose sawfly (Allantus cinctus)2 damages leaves and tunnels canes of rose in many midwestern and eastern states. The larvae are pastel green with numerous whitish spots and a yellow-orange head. They feed along the edges of leaves but remain curled and hidden on the undersides during the day. Most damage occurs when they then tunnel into canes and excavate the pith to produce a cell for pupation. Two generations per year are normally produced. Ardis brunniventris,2 sometimes known as the “rose tip sawfly,” is a European species of limited North American distribution that restricts feeding to the tips of roses, particularly rugosa types.  Hymenoptera: Cephidae; 2 Hymenoptera: Tenthredinidae

1

346

A

B D

E

C A. Symptom produced in raspberry by rose-shoot sawfly. WHITNEY CRANSHAW

B. Rose-shoot sawfly

larva in raspberry stem. WHITNEY CRANSHAW

C. Adult of the

F

rose-shoot sawfly. WHITNEY CRANSHAW

D. Rose-shoot sawfly

larva in rose stem.

JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

G

E. Injury symptoms

produced by willow shoot sawfly. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

F. Willow shoot sawfly larva in stem. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

H

G. Tunneling by willow

shoot sawfly larva.

JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

H. Adult of a shoot sawfly in oak. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

I. Symptoms of leaf flagging produced by maple petiole borer. DAVID SHETLAR

J. Maple petiole

borer larva. DAVID SHETLAR

I

J

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

REDNECKED CANE BORER

(Agrilus ruficollis)1

hosts Raspberries and blackberries Damage Damage is caused by the larvae, which develop and tunnel within canes, often near the base of the plant. Areas around where larvae feed produce a swelling and usually some associated splitting of the bark. Canes that are tunneled are considerably weakened and will often break. Damaged canes are also less productive, with reductions in number and size of fruit. Distribution Rednecked cane borer is a common species in the midwestern states but occurs over a broad area east of the Mississippi. Appearance Adults are dully metallic black with a coppery red or golden area behind the head (prothorax). Body form is elongate, and they are about ¼ inch long. Larvae, found within the plant, are pale-colored, elongatedbodied, with a slightly flattened area behind the head and a pair of hornlike projections on the hind end. Life History and Habits Rednecked cane borer spends winter as a full-grown larva within a chamber excavated in the cane. Pupation occurs in early spring, and about a month later adults begin to emerge. Adults are usually present from May into August. Adults will feed some on the leaves, chewing irregular holes in the upper surface. After feeding for a couple of weeks, females begin to lay eggs on young primocanes, which they cover with a yellow, viscous material that protects the eggs. Upon hatch the larvae immediately enter the cane and tunnel in the cambium, making feeding galleries in the form of a series of tight spirals. Areas injured in this manner swell, producing an elongate gall-like swelling. Older larvae will feed more deeply, including the pith, and extend tunnels for several inches both below and, particularly, above the galled area

Related Species Rose stem girdler (Agrilus cuprescens),1 also known as the “bronze cane borer,” also develops in blackberry and raspberry but has a wider host range than the rednecked cane borer that includes roses and currants (Ribes spp.). Adults are uniformly bronze-colored and usually present in late spring and early summer. Eggs are glued to canes, and larval feeding initially produces a spiral tunneling of the cambium. Rose stem girdler is a non-native species that has broadly colonized North America. The hickory spiral borer (Agrilus torquatus)1 girdles the twigs of hickory and pecan (Carya). Adults are present in late spring and early summer and initially chew on leaves. Females then glue eggs on the bark, typically near the base of current season shoots. Upon hatch the larva enters the twig and begins to tunnel. At the end of the first year it produces spiraling tunnels that girdle the twig, causing the terminal growth to wilt and often later drop from the tree. Older larvae more deeply tunnel into the side branch during the second year, where they spend the second season. Pupation occurs in spring of the second year. Other insects produce similar injuries to oak. Agrilus arcuatus appears to be the primary twig girdling Agrilus in eastern North America, associated with northern red oak. Agrilis angelicus girdles twigs of several California species of oak. Twig girdling in hazel (Corylus) can be produced by two species: Agrilus fulgens and A. corylicola. Larvae of A. cyanescens can be common in the branches of honeysuckle shrubs, particularly those in stressed sites. The adult has metallic dark bluish coloration. 1

Coleoptera: Buprestidae

348

A

B

C A. Rednecked cane borer. SUSAN ELLIS, BUGWOOD.ORG

B. Larval tunneling of

raspberry by rednecked cane borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

C. Swelling of boysenberry

cane produced at site of larval tunneling by rednecked cane borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

D

D. Injury symptoms to raspberry produced by rednecked cane borer.

E

RIC BESSIN, UNIVERSITY OF KENTUCKY

E. Rose stem girdler. WHITNEY CRANSHAW

F. Tunneling of rose stem

girdler in raspberry cane. WHITNEY CRANSHAW

G. External symptoms

F

G

of larval tunneling by rose stem girdler.

JAMES W. AMRINE JR., WEST VIRGINIA UNIVERSITY, BUGWOOD.ORG

H. Rose stem breakage due to injury by rose stem girdler. JAMES W. AMRINE JR., WEST VIRGINIA UNIVERSITY, BUGWOOD.ORG

I. Larva of a twig girdler of red oak, probably Agrilus arcuatus.

H

DAVID SHETLAR

I

J. Flagging caused by a

J

K

twig girdler of red oak, probably Agrilus arcuatus. JIM KALISCH, UNIVERSITY OF NEBRASKA

K. Adults of Agrilus

cyanescens, a borer of honeysuckle branches. WHITNEY CRANSHAW

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

OTHER BEETLES ASSOCIATED WITH TWIGS AND SMALL BRANCHES Hickory shoot curculio (Conotrachelus aratus)1 develops in the new shoots of hickory and pecan in the eastern U.S. Adults move to trees about the time of bud break, and females make puncture wounds near the base of leaf axils. Eggs are laid in these punctures, and larvae tunnel into the shoots. They feed until midsummer and leave the plants to pupate in soil at the base of trees. Adults emerge in late summer, feed briefly, and move to sheltered spots for overwintering. The closely related pecan shoot curculio (C. schoofi) damages hickory and pecan in a similar manner. Egg punctures are made below the base of the leaf petioles, and adults feeding in spring on shoots and leaves often cause some leaf curling. Oak bark beetles (Pseudopityophthorus spp.)1 develop primarily in oak but may infest buckeye, beech, chestnut, hickory, birch, and maple. They are particularly common in the Pacific States and are not aggressive species, limiting attacks to trees that are under stress or recently killed. Oak bark beetles are also suspected of being among the insects that transmit the fungus involved in oak wilt. The adults are tiny reddish brown to black beetles and feed on buds, twig crotches, and leaf axils before constructing longitudinal egg galleries at the junction of Tunnels under bark produced by walnut twig beetles with associated fungal cankers. the bark and sapwood. Two or more generations are WHITNEY CRANSHAW produced annually. Walnut twig beetle (Pityophthorus juglandis)1 develops in small branches of walnuts (Juglans). It is native to the southwestern U.S. and northern Mexico, associated with certain regional walnut species (J. major, J. californica) and causes only minor twig dieback on these species. In recent decades, however, walnut twig beetle has substantially expanded its range and made contact with additional walnut species, notably black walnut (J. nigra). Compounding plant health problems is a fungal associate of the beetle, Geosmithia morbida, which is introduced into trees when adult beetles make wounds for feeding or while excavating egg galleries. Growth of the fungus kills tissues under the bark, known as cankers, and cumulative effects of canker production results in a condition known as thousand cankers disease. Black walnut has proved to be particularly susceptible to this disease, which has resulted in extensive loss of black walnut in many areas of the western U.S.

350

A. Larva of hickory shoot borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

B. Adult hickory shoot borer. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

B

C. Walnut twig beetles. WHITNEY CRANSHAW

D. Egg gallery and

larval tunnels produced by walnut twig beetle. WHITNEY CRANSHAW

E. Full-grown larva

of walnut twig beetle. WHITNEY CRANSHAW

F. Walnut twig beetle

adults and pupae covered with spores of Geosmithia morbida. WHITNEY CRANSHAW

G. Exit holes made

A

by walnut twig beetles.

C

WHITNEY CRANSHAW

D

E

F

G

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

OTHER BEETLES ASSOCIATED WITH TWIGS AND SMALL BRANCHES Larvae of apple twig borer (Amphicerus bicaudatus)2 tunnel and girdle twigs of honeylocust, apple, grape, ash, tamarisk, and many other woody plants. This insect is a secondary pest in most situations, as larval attacks are restricted to parts of trees previously wounded or diseased and in decline. Adults that emerge in late summer may cut into healthy wood to feed and produce winter shelters. Adults are cylindrical, brown beetles about ¼ inch long. In spring they chew into the bark of twigs to lay eggs. The grublike larvae tunnel the twig as they develop, restricting feeding primarily to the pith and packing their tunnels with sawdust frass. Larvae feed throughout the summer, and most pupate in late fall in the larval tunnel. One generation is produced per season. right: Larva of the branch and twig borer. In the Pacific States, grape canes may also be tunneled by JACK KELLY CLARK, COURTESY Melalgus confertus,2 known as the “branch and twig borer.” OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM. Adults colonize plants that are injured or in decline, below: Puncture chewing pits into the bark, and the larvae develop within wounds made by adult of the grape the wood. Little injury normally occurs, as the larval cane girdler. tunneling is confined to dead wood, but adult feeding at DAVID SHETLAR the base of grape shoots can cause them to wilt. Madrone and oak are common native hosts for this insect. Shoots of grape and Virginia creeper may be damaged similarly in the Northeast and Midwest by grape cane girdler (Ampeloglypter ater).1 The shiny black beetle, about ⅛ inch long, cuts a small hole in the cane and lays a single egg. It then chews a girdling cut both above and below where the egg was laid. The shoot subsequently wilts and often drops from the plant. The larva tunnels the shoot and completes its development in it, emerging as an adult in late summer. Grape cane gallmaker (A. sesostris) develops in a similar manner. Girdling cuts are not made, but a swelling occurs around the site where eggs are laid and shoots are weakened. Twig girdler (Oncideres cingulata)3 produces conspicuous injury to several kinds of trees, although damage is peripheral and not serious to landscape trees. Adults neatly cut straight around the bark of small twigs (less than ⅜ inch in diameter) in September and October. Eggs are laid in the terminal, and larvae develop in the woody center of the plant. The life cycle is completed the following summer, with pupation in mid- to late summer. Hickory, pecan, elm, persimmon, and hackberry are among the most common hosts. Twig girdler is found primarily in the southeastern quadrant of the U.S. but Twig girdler injuries. JIM KALISCH, UNIVERSITY OF NEBRASKA occurs as far north as New England.

352

A

B

C D F

A. Apple twig borer adult

within shoot.

JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Apple twig borer. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Shoot feeding by an adult

of the branch and twig borer. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM.

D. Flagging of grape terminal

following shoot feeding by an adult of the branch and twig borer. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM.

G

H

I

E E. Grape cane girdler. DAVID SHETLAR

F. Flagging grape terminal produced by grape cane girdler damage. DAVID SHETLAR

G. Symptoms of injury produced

by grape cane gallmaker. DAVID SHETLAR

H. Adult and damage produced

by twig girdler.

JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Larva of twig girdler. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

OTHER BEETLES ASSOCIATED WITH TWIGS AND SMALL BRANCHES Flagging and twig breakage can also result from activity of southeastern gray twig pruner (Anelaphus villosus).3 Larvae develop in the center of twigs, and at the base of their tunneling they girdle the twig, leaving only the bark. Injured twigs usually drop from the tree, and the larvae continue to develop in the twig. Adults emerge in late April and May. Oak, elm, nut trees, flowering fruit trees, hackberry, maple, linden, honeylocust, and wisteria are among the host plants. A related species in Ontario and the northeastern U.S. is A. parallelus, associated with oak and hickory where is is called oak twig pruner. Small mulberry borer (Dorchaschema alternatum)3 is associated with small branches of trees in decline east of the Rocky Mountains. Mulberry, hickory, and dogwood are among the most common hosts. The genus Oberea3 contains several species that develop in twigs and canes of woody plants. Dogwood twig borer (O. tripunctata) develops on viburnum, dogwood, azalea, apple, stone fruits, blueberry, and laurel over a broad area of the eastern U.S. Adults are elongate, yellowish-tan beetles, about ½ inch long. Females make a series of punctures along the twig, about 3–6 inches from the tip, before laying eggs. The larvae originally tunnel between the punctures, then extend the feeding area by boring through the center of the twig. The life cycle is completed in 1 year in most areas, although it may take 2 years in the north. Raspberry cane borer (O. perspicillata) produces similar injuries to raspberry, blackberry, elm, hickory, dogwood, fruit trees, and rose in eastern North America. Other Oberea species include sassafras borer (O. ruficollis), oak sprout oberea (O. gracilis), poplar twig borer (O. delongi), sumac stem borer (O. ocellata), and azalea stem borer (Oberea myops). 1

Coleoptera: Curculionidae; 2 Coleoptera: Bostrichidae; 3 Coleoptera: Cerambycidae

top left: Larva of the dogwood twig borer. DAVID SHETLAR

bottom left: Larvae and shoot tunneling by poplar twig borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

below: Larva of sassafras borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

A

B

C D

E

F

A. Adult of the southeastern gray oak pruner. DAVID SHETLAR

B. Larva and damage produced by the southeastern gray oak pruner. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD. ORG

C. Adult of the small mulberry borer. DAVID SHETLAR

D. Adult of the dogwood twig borer. DAVID SHETLAR

E. Adult of the raspberry cane borer. JON YUSCHOCK, BUGWOOD.ORG

F. Larval tunneling by the raspberry

cane borer.

BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD. ORG

G. Flagging due to injury by sumac

stem borer.

JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD. ORG

H. Adult and leaf feeding injury by poplar twig borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD. ORG

G H

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

FLIES THAT DEVELOP IN SHOOTS, TWIGS, AND CANES OF DECIDUOUS TREES AND SHRUBS Larvae of rose midge (Dasineura rhodophaga)1 develop by feeding on the terminal growth of rose. Injuries can destroy flower buds and new shoot growth, resulting in blind shoots. More discussion about this insect can be found on page 582. Raspberry cane maggot (Pegomya rubivora)2 is an insect with wide distribution in North America that damages primarily raspberry; rose and blackberry are uncommon hosts. Adults are about ¼-inch gray flies that lay eggs in spring on the tips of rapidly growing canes. The larvae tunnel into the pith of the cane and produce a girdling cut just underneath the bark. The tips rapidly wilt and die beyond this injury, often dropping from the plant. The larvae continue to tunnel downward, usually pupating in the lower part of the cane. One generation is produced annually, with winter spent in the pupal stage. Several Phytobia species,2 known as cambium miners, develop in the tissues immediately underneath the epidermis on the trunks and branches of various thin-barked trees and seedlings. About eight species occur in the U.S. and Canada, including P. pruinosa in birch, P. setosa in red maple, and P. amelanchieris in serviceberry. Damage is insignificant, but the meandering tunnels in the bark sometimes attract attention. Similar bark mining in some deciduous plants, including rose, as well as some conifers may be produced by larval stages of several small moths in the genus Marmara.3 1

Diptera: Cecidomyiidae; 2 Diptera: Anthomyiidae; 3 Lepidoptera: Gracillaridae

SQUASH VINE BORER (Melitta cucurbitae)1 hosts Summer squash and winter squash or pumpkin among Cucurbita maxima. Other squash family plants are infrequently damaged. Damage Larvae tunnel into stems at the base of the plant. Coarse yellowish frass occurs in the stems, and rotting organisms often invade. Affected plants frequently wilt and die. Distribution Primarily found in the U.S. east of the High Plains, including the southern U.S. Appearance Larvae are white with a brown head and wrinkled body and are found in the stems at the base of the plant. Adult moths are wasplike, with an orange abdomen and metallic dark green thorax and forewings. The hindwings are transparent, and the legs are marked with feathery black and orange hairs. Life History and Habits Squash vine borer spends the winter in a cocoon in soil as either a full-grown larva or pupa. Adults may begin to emerge in mid-spring and are usually present as host plants begin to become established in late spring. The moths are active daytime fliers and glue their small, dull-red eggs to the base of the plant, at leaf axils, onto the undersides of leaves, and onto soil near the plant. Larvae bore into the base of the plant and feed for more than a month, migrating toward the base. When full grown they exit, burrow into the soil, and pupate in a dark brown cocoon mixed with soil. A second generation is common in the southern area of the range, with eggs laid during the latter half of summer. 1

Lepidoptera: Sesiidae

356

A

A. Terminal wilting due to rose midge feeding.

B

DAVID SHETLAR

C

D

B. Rose midge larvae

E

in shoot tip. DAVID SHETLAR

C. Raspberry cane

maggot larva in cane. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

D. Cambium miner tunneling in oak twig. DAVID SHETLAR

E. Cambium miner

tunneling in trunk of aspen.

WILLIAM JACOBI, COLORADO STATE UNIVERSITY

F

G

I

J

F. Squash vine borer larvae in squash stem. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Squash vine borer larva

excavated from base of squash. JIM JASINSKI, OHIO STATE UNIVERSITY EXTENSION, BUGWOOD.ORG

H. Squash vine borer eggs. JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Squash vine borer larva. DAVID SHETLAR

J. Mating pair of squash vine borers. JEFF HAHN, UNIVERSITY OF MINNESOTA

H

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

EUROPEAN CORN BORER

(Ostrinia nubilalis)1

hosts European corn borer is best known as a major pest that tunnels into stalks and ears of corn. It has an extremely wide host range, however, including such commonly grown plants as pepper, snap bean, chrysanthemum, dahlia, and several other ornamentals. Stems of seedling trees are also sometimes damaged by larvae. Damage Larvae develop by tunneling into stems, fruit, and other parts of the plant, causing weakening and allowing introduction of plant pathogens that produce rots. Distribution European corn borer is present over much of North America east of the Rockies Appearance The stage found in plants is a larva, within a stem, stalk, or fruit of a plant. Larvae are creamy to grayish in overall coloration, with some indistinct rows of small, round, brown spots running the length of its body. A full-grown larva is about 1 inch long. Life History and Habits Winter is spent as a full-grown larva in old plant debris. Pupation occurs in spring, and adults emerge in late spring and aggregate in dense grassy “action sites” for mating. Eggs are laid as masses on foliage. Early-stage larvae often tunnel into leaf veins, later moving into stalks or fruit as they get older. Pupation occurs in the plant, and there is usually a second generation in August. The biology is somewhat different in the extreme northern part of the range, along the U.S.-Canada border, where only one generation is produced. Furthermore, at least two strains of European corn borer occur in North America; they differ in the sex attractants they produce, among other ways. 1

Lepidoptera: Crambidae

Other Stem-boring Moths of Herbaceous Plants Stalk borer (Papaipema nebris)1 also has a very wide host range, having been recorded tunneling into more than 200 wild and cultivated plant stems. The larvae can damage corn, other small grains, and perennials, especially near where Joe-Pye weed, goldenrod, ragweed, and other tall-growing weeds are growing. Eggs overwinter attached to dead leaves and stems of common host plants. In May into June, the eggs hatch and young larvae often burrow into nearby grass stems. As the summer progresses, the larvae exit the grass stems and burrow into thicker stems of nearby plants. The larvae often push out moist frass pellets from a hole in the stem. Larvae take 2–3 months to mature. As they become larger, they take on a distinctively striped appearance, often with a brown band that lacks the stripes midbody. Mature larvae drop to the soil to pupate, and adults emerge in late August to mate and lay egg. Related species, the columbine borer (P. leucostigma) and coneflower borer (P. nelita), develop in stems of columbine and coneflower, respectively. Larvae are generally similar in appearance to the common stalk borer, and both occur in a broad area of the midwestern U.S. and south-central Canada. Two species with habits generally similar to those of stalk borer are potato stem borer (Hydraecia micacea)1 and hop vine borer (H. immanis). Both lay eggs among grasses in late summer, and eggs hatch in early spring. Larvae originally develop in grasses, later moving into stems of nearby plants. Potato stem borer is a European native that has spread through much of eastern Canada and is known to damage corn, potato, raspberry, rhubarb, onion, and hops. Hop vine borer is more common in the northern U.S. and has a host range more limited to grasses (including corn) and hops. Larvae are whitish with pale reddish to purple stripes and can be distinguished by the head color: brown in hop vine borer, yellow in potato stem borer. 358

A

B

C D

E F

G

A. European corn borer larva in corn stalk. DAVID KEITH, UNIVERSITY OF NEBRASKA

B. European corn borer adult. DAVID SHETLAR

C. European corn

borer egg mass. DAVID SHETLAR

D. European corn borer

egg mass at hatch.

JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Mature larva of

H

European corn borer. DAVID KEITH, UNIVERSITY OF NEBRASKA

I

F. European corn borer pupa. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. European corn borer

in Sycamore seedling.

JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

H. Stalk borer in stem.

J

DAVID SHETLAR

i. Stalk borer tunneling

injuries in rhubarb stalk. JIM KALISCH, UNIVERSITY OF NEBRASKA

j. Stalk borer larva. DAVID SHETLAR

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

STEM-BORING MOTHS OF HERBACEOUS PLANTS Limabean vine borer (Monoptilota pergratialis)2 infests lima bean and pole bean in the southeastern U.S. Early-stage larvae feed on the underside of leaves for about a week but then move to bore into stems. A slight swelling of the stem develops where larval tunneling occurs. Three generations may be produced annually. Larvae of the Eurasian hemp borer (Grapholita delineana)3 develop primarily in the stems of Cannabis. Stem injuries may be externally visible as small swellings and produce weakening that results in twigs to break. This insect has 2–3 generations per year and may also feed on leaves and developing seeds, which they loosely cover with silk. Larvae of some of the plume moths (page 556) develop in stems of plants, although injuries are rarely noticed. Perhaps most commonly observed among stem-boring species is Hellinsia kellicottii,4 a common borer in the stems of goldenrod. Carmenta anthracipennis,5 sometimes known as the “blazingstar borer moth,” develops in the stems of Liatris spp. in eastern North America. 1

Lepidoptera: Noctuidae; 2 Lepidoptera: Pyralidae; 3 Lepidoptera: Tortricidae; 4 Lepidoptera: Pterophoridae; 5 Lepidoptera: Sesiidae

SAWFLIES THAT DEVELOP IN STEMS OF HERBACEOUS PLANTS Wheat stem sawfly (Cephus cinctus)1 develops within the stems of many large-stemmed grasses and is a serious pest of wheat from the Prairie provinces into the Colorado. The insect has a 1-year life cycle and survives between seasons within the stem at the base of the plant. Adults emerge in spring, when temperatures get above about 62° F, and females insert eggs into the stems of growing host plants. When eggs hatch, the larvae tunnel into the stem and feed both above and below the point where eggs were laid. When full grown, they migrate to the base of the plant and make a girdling cut, creating a point of weakness where stems will then often break. They create an overwintering chamber below this point, sealed with excrement. The full-grown larva then enters a dormant condition (diapause) that lasts through winter, pupating in late winter or early spring. Wheat stem sawfly is found primarily in western North America, but a closely related species of similar habit, the European wheat stem sawfly (C. pygmaeus), occurs in eastern states. In the central valley and coastal ranges of California and southern Oregon, Calameuta clavata develops in native grasses. Adults are usually observed visiting yellow flowers. 1

Hymenoptera: Cephidae

360

A

B

C A. Limabean vine borer. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

B. External evidence of infestation by limabean vine borer.

D

CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

E

C. Eurasian hemp moth larva in stem. WHITNEY CRANSHAW

D. Eurasian hemp moth adults. WHITNEY CRANSHAW

E. Larva of a plume moth,

Hellinsia kellicottii, in goldenrod. DAVID SHETLAR

F. Stem breakage of goldenrod

due to damage by larva of Hellinsia kellicottii. DAVID SHETLAR

F

G

H

I

G. Adult of Hellinsia kellicottii. DAVID SHETLAR

J

K

H. Wheat stem sawfly. DAVID SHETLAR

I. Wheat stem sawfly ovipositing

into stem.

DARREN COCKRELL, COLORADO STATE UNIVERSITY

J. Stem breakage due to tunneling

of wheat stem sawfly.

FRANK PEAIRS, COLORADO STATE UNIVERSITY

K. Wheat stem sawfly larva in stem. FRANK PEAIRS, COLORADO STATE UNIVERSITY

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

BEETLES THAT DEVELOP IN STEMS OF HERBACEOUS PLANTS Potato stalk borer (Trichobaris trinotata)1 develops in the stems of potato, eggplant, and related nightshade family weeds in many of the southeastern states. Winter is spent in the adult stage, usually in previously infested stems. The adults become active in late spring and chew pits in stems of new plants, laying eggs in some. Larvae hollow out the stems during late spring and early summer, sometimes excavating down to the roots. They are rather elongate, about ½ inch long when mature, and pale yellow. They pupate in a cell made of chewed bits of stalk and transform to adults during the latter half of the summer. Adults are about 1⁄5-inch-long snout beetles. Most of the body appears grayish because it is covered with fine hairs, and the head is black. The related tobacco stalk borer (T. mucorea) occasionally damages potato in southern California and Arizona. Sunflower stem weevil (Cylindrocopturus adspersus)1 is the most important of the many insects that tunnel sunflower stalks in the central U.S. and Prairie Provinces. Adults are about 1⁄6-inch snout beetles, grayish brown with white spots on the back. They emerge from the soil in June and feed on plants, causing little observable injury. After a few weeks females begin to lay eggs, moving to the lower part of the stalk. Eggs are laid in small niches chewed in the stalk, with most eggs laid by midJuly. Newly hatched larvae tunnel into the stalk, where they feed in the pith. They work their way downward in the plant, and most pupate near the soil line. Feeding and the excavation of small chambers for overwintering larvae cause weakening, which allows stalks to break. Adult lizard beetles 2 are slender-bodied beetles, typically ½–⅜ inch in length, that are most often observed on flowers. Commonly encountered species in North America, in the genus Languria, are colorfully marked above: Lizard beetle with dark wings and a reddish thorax. Larvae of several species develop inside stems adult in plant stem. of plants. Most often found in gardens is the clover stem borer (Languria DAVID SHETLAR mozardi), 2 which has a very broad host range that includes rudbeckia, American below: Stem cutting of sunflower by adult bellflower, lupines, clovers, soybean, and many legumes. Acropteroxys gracilis2 is another dectes stem borer. common species of stem-dwelling beetle, with larvae that develop in the stems of WHITNEY CRANSHAW ragweed, chicory, and nettle. Larvae of the phlox stem borer (Oberea flavipes)3 burrow into phlox stems. The adult beetle chews irregular pits in leaves of the host plant. The dectes stem borer (Dectes texanus) is a common insect that develops in the stems of sunflower, ragweed, cocklebur, and soybeans and is present in a broad area east of the Rocky Mountains. Adults make cuts in the stems and lay eggs in pockets they chew out at the base of the leaf petiole. Larvae hatching from the eggs develop as borers within the pith of the plants, causing little injury during this pith-feeding period. Late in development the full-grown larvae settle near the base of the plant and establish a site for pupation, often incidentally girdling the plant during this activity. 1

Coleoptera: Curculionidae; 2 Coleoptera: Erotylidae; 3 Coleoptera: Cerambycidae

362

A

B C D

E

A. Potato stalk borer. JESSICA LOUQUE, SMITHERS VISCIENT, BUGWOOD.ORG

B. Larva of sunflower stem weevil. FRANK PEAIRS, COLORADO STATE UNIVERSITY

F

C. Sunflower stem

weevil.

FRANK PEAIRS, COLORADO STATE UNIVERSITY

D. A lizard beetle, Acropteroxys gracilis. DAVID SHETLAR

G

E. Clover stem borer. TOM MURRAY

F. Lizard beetle larva

in plant stem. DAVID SHETLAR

G. Phlox stem borer. DAVID SHETLAR

H. Dectes stem borer. WHITNEY CRANSHAW

H

I. Larva of a dectes

stem borer in soybean stem.

JIM KALISCH, UNIVERSITY OF NEBRASKA

I

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

FLIES THAT DEVELOP IN STEMS OF HERBACEOUS PLANTS Among the many insects that tunnel stems of sunflower is sunflower maggot (Strauzia longipennis).1 Helichrysum species may also be damaged. Most feeding occurs in the pith, but heavily infested plants are weakened, and stems may break. Swede midge (Contarinia nasturtii)2 feeds on a wide variety of cruciferous plants (e.g., cabbage, broccoli, cauliflower) and related weeds. Adults lay eggs in small batches near the growing points of the plants and the larvae feed by slicing cells and feeding on the released fluids. These feeding injuries can produce a wide range of symptoms, depending the number of insects present and the growth stage of the plant. More subtle symptoms may involve swelling at the base of leaves and leaf puckering. Distortion of the new growth can be severe and growing points may be killed, either directly by the insect injuries or from fungi or bacteria that enter wounded tissue. Swede midge is native to Europe but has recently become established in parts of North America and is presently known to occur in Ontario and New York.  Diptera: Tephritidae; 2 Diptera: Cecidomyiidae

1

PITH-NESTING BEES AND WASPS Several kinds of solitary bees nest in cavities, and some of these will excavate the exposed pith of plants in construction of nest sites. Often most commonly encountered are small carpenter bees (Ceratina spp.)1 that nest in the stems of plants such as rose, various caneberries, sumac, butterflybush, and elder. Most are fairly small (ca. ¼ inch) dark bees with a slight metallic sheen. During nesting, the mother cuts a tunnel through the center of the stem and creates a series of individual nest cells, each separated with chewed plant fibers. Each nest cell is provisioned with sufficient pollen and nectar to support a single bee larva, then it is sealed and a new cell is developed. The nest-building activities of small carpenter bees usually cause little additional dieback of pruned canes. Other cavity-nesting solitary bees that may occur in stems include leafcutter bees (Megachile spp.)2 (page 168) and mason bees (Osmia spp.)2 (page 676). Large carpenter bees (Xylocopa spp.)1 are quite large, usually black or metallic dark green, and resemble bumble bees but lack hair on the abdomen. Large carpenter bees nest in dry wood and do not normally damage plants. In southern and western states, some species may burrow into the stems of lilac or oleander. However, they are sometimes considered pests of building timbers and can occur in many wooden garden structures, especially wooden fencing. Females chew out narrow burrows in the wood that are provisioned with pollen and nectar. The males, which do not sting and are harmless, aggressively defend territories and will buzz humans. Tunneling of plant stems can also be done by several hunting wasps that nest in cavities. In some areas, Pemphredon species3 wasps are common inhabitants of stems of rose or other pithy plants. These hunt aphids, which they paralyze and pack into excavated nest cells as food for the developing wasp larvae. Tunneling is confined to the pith and does not damage living tissues of the cane.  Hymenoptera: Apidae (Xylocopinae); 2 Hymenoptera: Megachilidae; 3 Hymenoptera: Crabronidae

1

364

A B

C A. Swede midge larva.

D

SUSAN ELLIS, USDA APHIS PPQ, BUGWOOD.ORG

B. Swede midge adult. SUSAN ELLIS, USDA APHIS PPQ, BUGWOOD.ORG

C. Distorted growth due

to swede midge damage to growing point of cabbage. JULIE KIKKERT, CORNELL COOPERATIVE EXTENSION, BUGWOOD.ORG

2 mm

D. Adult of the sunflower maggot. WHITNEY CRANSHAW

E

F

G

H

I

E. Small carpenter bee. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Pupae, larvae and an adult small carpenter bee in a rose cane. DAVID SHETLAR

G. Nest cells of a leafcutter

bee in a rose cane. DAVID SHETLAR

H. Leafcutter bee. WHITNEY CRANSHAW

I. Large carpenter bee. DAVID SHETLAR

J. Pemphredon wasp nesting

in pith of bamboo. WHITNEY CRANSHAW

K. Pemphredon wasp larva and

pupae within a raspberry cane. WHITNEY CRANSHAW

J

K

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

APHIDS THAT DEVELOP ON STEMS, TWIGS, SHOOTS, AND CANES Most aphids are found on the foliage of plants; however, a few species occur exclusively or primarily on twigs, small branches, and shoots. In general, these aphids tend to be somewhat larger than “typical” aphids that feed on leaves, with longer mouthparts that allow access to the phloem from the stems and branches. Giant bark aphid (Longistigma caryae)1 is the largest aphid (ca. ¼ inch) found in the U.S. It feeds on branches of many types of trees, including sycamore, linden, willow, birch, and many nut trees, but is associated primarily with oak. They often occur in groups and because of their large size (for an aphid) are sometimes mistaken for ticks, spiders, or other arthropods. Giant bark aphids also excrete large amounts of honeydew that can attract nuisance numbers of wasps and bees and drop sticky honeydew onto surfaces below. Another unusually large aphid is the giant willow aphid (Tuberolachnus salignus),1 a purplish aphid associated with limbs of willow. Approaching it in size and also found on willow is the black willow aphid, Pterocomma smithiae.2 The black willow aphid also occurs on Populus, which host several other Pterocomma, including P. bicolor and P. pseudopopueum. Several Chaitophorous Giant conifer species occur on stems of Populus as well, including Chaitophorus aphids on juniper. 3 populicola (dusky-winged poplar aphid) and C. nudus. WHITNEY CRANSHAW Winged forms of these aphids have conspicuous wing markings with black wing veins, bordered in dark. The largest aphids associated with limbs of conifers are the giant conifer aphids (Cinara spp.).1 Most species of pines, fir, Douglas-fir, junipers, and spruce host one of these aphids, and each Cinara species is specific to a particular genus of tree, some even to a particular species. They feed on the phloem sap from twigs, branches, and trunks; they occur in large groups but may not be easily observed as they blend with bark. Some species have very long legs, causing them to appear spiderlike to many. Heavy infestations cause a yellowing of foliage and needle drop and occasionally cause dieback of shoots. Plants under a prolonged period of stress (e.g., drought) tend to be more susceptible to outbreaks of giant conifer aphids. Rose aphid (Macrosiphum rosae)2 is the most common aphid found on rose, although the closely related potato aphid (M. euphorbiae) also develops on rose. Infestations of rose aphid are usually concentrated around new shoots and flower buds, and during sustained outbreaks these insects can reduce flower size and may even kill buds. Aphids may also feed on flower petals after bud break, causing losses in flower quality. Both rose aphid and potato aphid are moderately large (⅛ in.) aphids and both have a range in color forms. Potato aphids are typically green, but pink forms occur. Rose aphids are typically pink or purplish, but green and yellowish forms also occur, and multiple color morphs may be present within a single colony. Uroleucon is a large genus of aphids, containing more than 90 species in North America, most of which occur on aster family plants such as goldenrod. Most conspicuously observed are large, bright red species that may build dense colonies on stems; other common representatives are dull brown, various shades of brown, or shiny black. 1

Hemiptera: Aphididae (Lachninae); 2 Hemiptera: Aphididae (Aphidinae); 3 Hemiptera: Aphididae (Chaitophorinae)

366

A D

E

B F

C G H

I

A. Giant bark aphids

on oak branch.

HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

B. Giant willow aphids. WHITNEY CRANSHAW

C. Black willow aphids. WHITNEY CRANSHAW

D. A Chaitophorous species

aphid on cottonwood twig. WHITNEY CRANSHAW

E. Dusky-winged

poplar aphid.

WHITNEY CRANSHAW

F. Giant conifer aphids on spruce. STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

G. Rose aphids, red form.

J

K

L

WHITNEY CRANSHAW

H. Rose aphids, green form. DAVID SHETLAR

I. Overwintering

eggs of rose aphid. WHITNEY CRANSHAW

J. Rose aphid colony

with mixture of colors. WHITNEY CRANSHAW

K. Brown ambrosia aphids. DAVID SHETLAR

L. A colony of Uroleucon

species aphids. DAVID SHETLAR

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

APHIDS THAT DEVELOP ON STEMS, TWIGS, SHOOTS, AND CANES

Woolly Apple Aphid (Eriosoma lanigerum)1 hosts Apple, crabapple, hawthorn, mountain-ash, pyracantha, elm. Damage On apple, crabapple, and other summer hosts, woolly apple aphid colonizes roots, trunks, and branches, concentrating around previous wounds and callous tissues. Feeding interferes with normal wound healing and contributes to the production of knotlike growths. On roots, these may become pronounced swellings that can girdle and kill roots. On the primary (winter) elm host, infestations of emerging spring growth cause leaves to curl into closed, stunted clusters or rosettes at the twig tips. Distribution Throughout North America in association with its hosts. Appearance Dark purplish brown, but aboveground forms are densely covered with white wax. Forms produced belowground or in leaf curls are less densely covered than those colonizing trunks and branches. Life History and Habits In the complete life cycle there is both a winter host of elm and summer hosts of apple, crabapple, or mountain-ash. Eggs survive on the winter host, and the aphids emerge in spring, subsequently producing a curling of leaves on elm. After a few generations, winged forms are produced that disperse to apple and crabapple. On these hosts they produce a more densely woolly form that typically colonizes callous tissue surrounding previous wounds on trunks, branches, and larger roots. Multiple generations are present on this summer host. In early fall, winged forms return to elm. Mating occurs among sexual forms, and a single overwintering egg is laid by each mated female, near elm buds. There may be variations in this life cycle in warmer areas, particularly where elm is not available as a winter host. Under these conditions woolly apple aphid may continually reproduce on roots or trunks of trees.

Other Woolly Aphids on Twigs, Branches, and Trunks The woolly hawthorn aphid (Eriosoma crataegi)1 and the woolly pear aphid (E. pyricola) develop on twigs and small branches of hawthorn and cultivated pear, respectively. Other Eriosoma species occur on foliage of elm or other hosts. Woolly elm bark aphid (E. rileyi) restricts feeding to slippery and American elm, forming dense colonies on small branches. Woolly alder aphid on maple. Woolly alder aphid (Paraprociphilus tessellatus)1 is a conspicuous JIM KALISCH, UNIVERSITY OF NEBRASKA species associated with branches of alder during the summer months. Maples, usually silver maples, are the winter host and it may be found on both the leaves and stems of this host. Beech blight aphid (Grylloprociphilus imbricator)1 develops in colonies on the bark of American beech. They continuously secrete honeydew that supports growth of a sooty mold fungus (Scorias spongiosa) that can grow into a conspicuous spongy mass. These aphids unusually wiggle their bodies, in mass, when disturbed. Balsam twig aphid (Mindarus abietinus)2 is a European native that infests true fir species, primarily in eastern North America. The most noticed forms are the spring stem-infesting females that produce considerable waxy threads. These commonly curl or distort the emerging needles. Summer forms are rarely noticed, but these produce sexual forms that lay eggs that overwinter. 1

Hemiptera: Aphididae (Eriosomatinae); 2 Hemiptera: Aphididae (Mindarinae)

368

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C

D A E

F

G

H

I

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A. Woolly apple aphid colony. JOSEPH BERGER, BUGWOOD.ORG

B. Woolly apple aphid colonizing small branch of crabapple. WHITNEY CRANSHAW

C. Close-up of woolly

apple aphid colony.

JOSEPH BERGER, BUGWOOD.ORG

D. Callous tissue growth on twig at

areas wounded by woolly apple aphid. DAVID SHETLAR

E. Woolly apple aphid colony on

knot of callous tissue on trunk. DAVID SHETLAR

F. Perennial canker on trunk

K

L

of apple resulting from repeated infestation of woolly apple aphid. HAROLD J. LARSEN, COLORADO STATE UNIVERSITY

G. Woolly hawthorn aphids. DAVID SHETLAR

H. Woolly pear aphids. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

I. Woolly alder aphid on maple. JIM KALISCH, UNIVERSITY OF NEBRASKA

J. Beech blight aphids. DAVID SHETLAR

K. Balsam fir aphids, close-up. DAVID SHETLAR

L. Balsam fir aphids on

new terminal growth. DAVID SHETLAR

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

ADELGIDS THAT DEVELOP ON TWIGS AND TERMINALS OF CONIFERS Adelgids1 are a family of “woolly” aphidlike insects associated with conifers. Their life histories differ in some respects from those of “true” aphids, notably in that eggs are produced each generation. Host alternation is common with many species, usually between two conifer species, and some induce galls on the primary host (page 422).

Hemlock Woolly Adelgid (Adelges tsugae)1 hosts Hemlock, with Canada and Carolina hemlock most seriously damaged. Damage Hemlock woolly adelgid feeds on sap from twigs and concurrently introduce saliva that is toxic to the plant. Foliage of infested plants yellows, and needles drop prematurely, particularly on interior areas of branches. Dieback of limbs is common, and trees have often been killed by this insect. This insect has produced very extensive loss of trees, particularly Carolina hemlock growing in the southern Appalachians. Heavily infested trees appear white from the copious white wax produced by the egg-laying females. Distribution Hemlock woolly adelgid is native to Asia and was accidentally introduced into the Pacific Northwest almost a century ago. Damage produced to the hemlock species native to that region, western hemlock, is minor. It subsequently spread to eastern North America and has become generally distributed in areas east of the Appalachian Mountains, from South Carolina to Maine, west to eastern Kentucky and southeastern Ohio. Appearance Adult forms are nearly black but often covered with white cottony wax. Early instars are are much smaller than the adult and often dark reddish gray. A white fringe of wax does develop around the body of most stages. Egg-laying females form a ⅛-inch diameter ball of waxy threads on the undersides of twigs. Life History and Habits Winter is spent in the form of adults on twigs, with females beginning to lay eggs in late March. Eggs hatch in April, and this first generation is usually completed by early summer. A second generation follows and goes temporarily dormant during midsummer, resuming growth in fall.

Other Adelgids Associated with Twigs and Terminals of Conifers Balsam woolly adelgid (Adelges piceae) is an introduced species now found in forests of both the northeastern and northwestern U.S. and areas of southern Canada. It is an important pest of balsam and Fraser fir, with large colonies often developing on needles and bark of trunks, branches, and twigs. Heavy infestations often result in gouty distortions that weaken twigs and small branches and often kill terminal buds. Two generations are produced annually, with winter spent as a first-stage nymph on the bark. Various woolly pine adelgids (Pineus spp.)1 are associated with needles, twigs, branches, and trunks of pine. Individual insects are densely covered with whitish wax. Foliage of heavily attacked trees becomes yellowish, and growth is stunted. Needle and shoot feeding can cause shoots to droop and die. Species capable of developing dense colonies on trunks and branches are potentially most damaging. Perhaps the most important species in North America is pine bark adelgid (P. strobi) which colonizes the bark, candles, and needle bases of white, Austrian, and Scotch pine. All stages apparently occur on pine. Some other Pineus species alternate between pine and spruce. 1

Hemiptera: Adelgidae

370

B

C

A A. Heavy infestation of

hemlock woolly adelgid. USDA FOREST SERVICE SOUTHERN RESEARCH STATION, USDA FOREST SERVICE, SRS, BUGWOOD.ORG

B. Hemlock woolly adelgids. DAVID SHETLAR

C. Eggs and crawlers of

hemlock woolly adelgid. LORRAINE GRANEY, BARTLETT TREE EXPERTS, BUGWOOD.ORG

D

D. Balsam woolly adelgids.

E F

DAVID SHETLAR

E. Eggs of balsam

woolly adelgid.

RONALD S. KELLEY, VERMONT DEPARTMENT OF FORESTS, PARKS AND RECREATION, BUGWOOD.ORG

F. Damage to terminal growth produced by balsam woolly adelgid. DAVID SHETLAR

G. Pine bark adelgid

infestation of trunk. DAVID SHETLAR

H. Pine bark adelgid, close-up. DAVID SHETLAR

I. Pine bark adelgids colonizing

branch.

DAVID SHETLAR

H

I

G

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

MEALYBUGS ASSOCIATED PRIMARILY WITH STEMS AND TWIGS Mealybugs are fluid feeding insects that are normally covered with a whitish wax. Many species also use wax to form a loosely constructed egg sac, giving colonies a cottony appearance. Approximately 280 species of mealybugs are known to occur in North America, with species that can occur on leaves, stems, fruit, and/or roots. Those observed primarily on leaves are discussed in chapter 3 and root-feeding species in chapter 6. Hawthorn mealybug (Phenacoccus dearnessi)1 is most consistently noticed when the late stage nymphs and adults mature on the twigs of hawthorn. (Less common hosts include pyracantha, mountain-ash, and amelanchier.) Mature females are reddish, covered with a neat coating of white wax, and have a globular appearance. In high populations feeding injuries by hawthorn mealybug can produce significant twig dieback and large amounts of honeydew are excreted. Hawthorn mealybug spends the winter as a late-stage nymph on trunks and larger branches, packed in cracks on the bark. In spring, females migrate to twigs where they continue to develop to the adult stage. Adult males, which are winged and gnat-like, emerge at this time and, after mating, the females begin to swell greatly as they mature eggs. Eggs are produced and hatch over a period of several weeks, with the crawlers moving to leaves, settling along the main veins and leaf folds, where they feed through summer. In late summer and early autumn they migrate to the trunk where they settle and remain through winter. A single generation is produced per year. There are several other related species associated with twigs of trees and shrubs. Maple mealybug (Phenacoccus acericola) is found in the northeastern quadrant of the U.S. and areas of southeastern Canada. Nymphs develop on leaves and adults on twigs of maple, buckeye, basswood, and viburnum. Two to three generations are produced annually. APPLE MEALYBUG (P. aceris) is a European species found in the northeastern and northwestern states. It has a wide host range that includes primarily rosaceous trees and shrubs such as pyracantha, apple, cotoneaster, mulberry, and mountain-ash. This species overwinters as a second instar on twigs, and one generation is produced annually. Another recently introduced species is Japanese mealybug (P. japonicus), a pest of azalea in the Mid-Atlantic States. Grape mealybug (Phenacoccus maritimus)1 is most commonly associated with pear, grape, and catalpa. Several other plants, including Taxus, honeylocust, and hackberry, are reported to be susceptible. Overwintering stages are early-instar nymphs found in or near the cottony egg sacs. In spring, most of these nymphs move to twigs and leaves where they feed and develop, becoming full grown in late June and July. This first, overwintered generation is usually little observed. Eggs are laid in early summer, and nymphs of the second generation develop in July and August. When full grown they move to older wood, where the females again produce egg sacs. Egg production may continue until killing frosts. Taxus mealybug (Dysmicoccus wistariae)1 is a common species associated with Taxus in the northeast and midwest states. Occasionally it is also found on dogwood. It develops on stems and branches, clustering at forks, and can cause yellowing of plants. Taxus mealybug also produces large amounts of honeydew. Winter is typically spent as a nymph that resumes feeding in late May. Two or three generations may be produced annually in southern areas, one in the north. Cypress bark mealybug (Ehrhornia cupressi)1 can be a serious pest of Monterey cypress and some related plants in the Pacific states. It is not often observed because it develops protected beneath bark flakes. One generation is produced annually. Hemiptera: Pseudococcidae

1

372

A

B

C D

E

A. Mature hawthorn mealybugs.

F

WHITNEY CRANSHAW

B. Hawthorn mealybug with eggs and crawlers. WHITNEY CRANSHAW

C. Hawthorn mealybug

nymphs on leaves. WHITNEY CRANSHAW

D. Hawthorn mealybug male

and overwintering stages on bark of trunk. WHITNEY CRANSHAW

E. Grape mealybugs on grape vine. WHITNEY CRANSHAW

G H

F. Grape mealybug on fruit. HAROLD J. LARSEN, COLORADO STATE UNIVERSITY

G. Mealybug on ash with

associated honeydew. WHITNEY CRANSHAW

H. Apple mealybug male and cocoons. DAVID SHETLAR

I. Taxus mealybugs. DAVID SHETLAR

J. Cypress bark mealybugs. US NATIONAL COLLECTION OF SCALE INSECTS PHOTOGRAPHS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

I

J

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

ERIOCOCCID SCALES COMMONLY OBSERVED ON TWIGS Adults of eriococcid or “feltlike” scales (Eriococcidae family)1 often produce some whitish wax that can give them a superficial resemblance to mealybugs. Nymphal stages of some species develop on foliage, but the more conspicuous adults settle and mature on twigs and branches.

European Elm Scale (Gossyparia spuria)1 hosts Elm, particularly American and rock elm Damage European elm scale feed on the leaves during summer then aggregate on twigs and small branches during the adult stage. Sustained high populations seriously weaken branches, often producing premature leaf yellowing (flagging) during autumn and die back of branches. Heavy infestations cause dieback of twigs and branches. European elm scale can cause serious nuisance problems because of honeydew production, with peak production in June and early July when the females mature. Problems with this species are particularly severe in the Rocky Mountain region, where it can often be the most important honeydew-producing species associated with street trees. Distribution An introduced species now found throughout North America in association with its elm host. Appearance Mature females are broadly oval, swollen, and dark gray with a pronounced whitish fringe of wax around the edge of the body. Males are much smaller and produce an elongate white cocoon. Nymphs on leaves are yellowish brown with some whitish wax. European elm scale has reddish brown blood. Life History and Habits European elm scale spends the winter as second-instar nymphs, packed into cracks on twigs and smaller branches. The nymphs are oval in general form and pale gray because of the light waxy cover of the body. In spring they resume development, and the females swell greatly. During late April and May, the winged male scales begin to emerge from the small white cocoons they produce. Males are not always produced, however, and this species can reproduce asexually. Eggs hatch in the body of the female, and crawlers emerge over a period of several weeks, peaking between midJune and mid-July. They move to leaves and settle on the leaf underside, the dark yellow nymphs almost always found tucked next to main leaf veins. In late summer they migrate back to the twigs.

374

A A. Mixture of mature females and male cocoons of European elm scales.

B C D

WHITNEY CRANSHAW

B. Male mating with

mature female European elm scale. WHITNEY CRANSHAW

C. Mature female

European elm scales. WHITNEY CRANSHAW

D. European elm scale crawlers. WHITNEY CRANSHAW

E. European elm scale

nymphs on leaves. WHITNEY CRANSHAW

E

F. Yellow foliage “scale

flagging” resulting from heavy infestation of European elm scale. WHITNEY CRANSHAW

G. European elm scale

in overwintering stages on small branches. WHITNEY CRANSHAW

F

G

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

ERIOCOCCID SCALES COMMONLY OBSERVED ON TWIGS

Other Eriococcid Scales Azalea bark scale (Eriococcus azalae)1 is an introduced species that has spread through much of the easten U.S. and is now present in parts of the Pacific Northwest. Azalea and rhododendron are hosts. Large numbers of insects may colonize branches and produce large amounts of honeydew that supports growth of sooty molds. Another exotic species, first detected in Texas in 2004, is the crapemyrtle scale (E. lagerostroemia), associated with crape myrtle. It is now found over a wide area that includes most southeastern states. Some other eriococcids that occur in North America include oak eriococcin (E. quercus), a native species that develops on new growth of oaks, found primarily in the southeastern states; Norfolk Island pine eriococcin (E. araucariae), an uncommon insect associated with Norfolk Island pine; and Gillette eriococcin (E. gillettei), associated with juniper. Beech scale (Cryptococcus fagisuga)1 is an introduced species that has contributed greatly to the death of beech trees. Originally found introduced in the northeastern U.S. and adjacent areas of Canada, it has extended into the Carolinas and as far west as Michigan. Beech scale develops on trunks and branches of American beech and covers itself with whitish wax. Primary damage is weakened trees and wounds that allow canker-producing fungi (Nectria coccinea var. faginata, N. galligena). The combined action of the scale and fungi can seriously weaken and often kill trees, a condition known as beech bark disease. 1

Hemiptera: Eriococcidae

Sooty mold resulting from honeydew produced by azalea scale. DAVID SHETLAR

376

A

B

C D

E A. Azalea scales.

E. Oak eriococcin.

DAVID SHETLAR

B. Azalea scale, close-up

US NATIONAL COLLECTION OF SCALE INSECTS PHOTOGRAPHS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

DAVID SHETLAR

F. Beech scale.

of mature females.

C. Azalea scale with eggs. ROBIN ROSETTA, OREGON STATE UNIVERSITY

D. Crapemyrtle bark scale. MICHAEL MERCHANT, TEXAS COOPERATIVE EXTENSION, BUGWOOD.ORG

F

G

WHITNEY CRANSHAW

G. Heavy beech scale

infestation of trunk.

JOSEPH OBRIEN, USDA FOREST SERVICE, BUGWOOD.ORG

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

SOFT SCALES OBSERVED PRIMARILY ON TWIGS The soft scales make up one of the largest (ca. 1,000 North American species) and most important families (Coccidae)1 of scale insects. Most are broadly oval in form and may swell to a large hemispherical form when eggs are maturing. Soft scales suck fluids from the phloem of plants and most excrete conspicuous amounts of honeydew. Soft scales retain some mobility during the nymphal stages, and many may occur on both foliage and stems. The majority of species most often ultimately settle on twigs in the adult form, but a few commonly mature on foliage (page 266). Adult females are the stage most often noted, as they greatly swell with egg production. Most, but not all, soft scales produce males, which are much smaller than the females and winged in the adult stage.

European Fruit Lecanium (Parthenolecanium corni)1 hosts A wide range, including most fruit trees and many shade trees. Stone fruits (Prunus), redbud, American elm, maple, poplar, and willow are common hosts. Other common names sometimes used to describe this species include “brown apricot scale” and “brown elm scale.” Damage European fruit lecanium is a soft scale that feeds on the phloem of small branches. Under sustained outbreaks, it can cause decline and dieback, but it is often under a high level of natural control, largely from parasitoids, that usually prevents sustained outbreaks. European fruit lecanium is also capable of producing large amounts of honeydew, which can be a serious nuisance problem and favors the growth of sooty mold. Distribution Throughout North America, common. Despite its name, it is apparently native. Appearance Adult females swollen with eggs are generally hemispherical and often light to dark brown with mottling. Color and shape often alter depending on host. Coverings of the males are more flattened and reticulated. Life History and Habits Winter is spent in protected sites as nymphs on wood of small branches that are 1–3 years old. They resume development in spring, with first adults present in April and May. European fruit lecanium reproduces asexually, and the females swell with maturing eggs in mid- to late spring. Eggs hatch over a period of weeks, producing a much-extended period of crawler activity, and these young stages move to foliage where they settle and feed for a month or two. By late summer and early autumn, all will have migrated back to twigs, where they will subsequently spend winter. One generation is normally produced, but in areas of California it has been observed that part of the population may produce a second generation, with crawlers produced in midsummer.

Other Lecanium-Type Soft Scales Fletcher scale (Parthenolecanium fletcheri)1 is associated with certain juniper, arborvitae, baldcypress, and yew. It is particularly abundant in the Midwest, where it is an important pest in nurseries. Serious problems in landscape settings are infrequent. European peach scale (P. persicae) is generally distributed in North America and has a wide host range among deciduous trees and shrubs. Ornamentals, including honeysuckle, grape, barberry, euonymus, and silk tree, are most commonly infested. Frosted scale (P. pruinosum) is found in the Pacific States and has a host range and life history similar to that of European fruit lecanium. It is most commonly reported as damaging walnut and stone fruits. Oak lecanium (P. quercifex) develops on oak, beech, sycamore, hickory, and a few other shade trees.

378

A

B

C D

E

F

G

A. Mature female European fruit lecanium. WHITNEY CRANSHAW

B. Cover of male European fruit lecanium. WHITNEY CRANSHAW

C. European fruit lecanium with recently

settled crawlers.

BOB HAMMON, COLORADO STATE UNIVERSITY

D. Fletcher scales, mixed stages. DAVID SHETLAR

H

E. Fletcher scales, maturing females. DAVID SHETLAR

F. Oak lecanium adult female. DAVID SHETLAR

G. Oak lecanium opened to expose eggs. DAVID SHETLAR

H. Oak lecanium developing on oak twig. WHITNEY CRANSHAW

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

SOFT SCALES OBSERVED PRIMARILY ON TWIGS Magnolia scale (Neolecanium cornuparvum)1 is one of the largest and most conspicuous scales. It is found primarily on magnolia in the midwestern and Mid-Atlantic states. High populations encrust branches, causing dieback, and it is a prolific producer of honeydew. Winter is spent as nymphs on 1- to 2-year-old twigs. The nymphs begin to molt to the adult stage in early to mid-May. The females subsequently begin to swell with eggs, and the newly hatched crawlers may be common from mid-July into early September. Adult females are almost ½ inch in diameter, irregularly shaped, and shiny light brown. Young adults are covered with fine wax, which tends to be lost about the time eggs start to hatch. The native terrapin scale (Mesolecanium nigrofasciatum)1 is an occasional pest of blueberry and peach, although natural enemies usually adequately suppress populations. Maple and sycamore are other common hosts. The mature adults have a hemispherical cover with distinct radiating black bands. Winter is spent as a mated female on the twigs. Eggs hatch in the mother in spring, and the crawlers move to foliage where they feed during the summer. A reverse migration back to twigs occurs in fall. Mature females of calico scale (Eulecanium cerasorum)1 are round, about ¼ inch in diameter, and mottled conspicuously with white and black. They occur in the Pacific States and have become established from Indiana to New England and south to Virginia. All stone fruits are hosts, as are many vines, crabapple, elm, pyracantha, honeylocust, maple, dogwood, sweetgum, and several other plants. Nymphs feed on leaves in summer and then move to twigs in fall. Females mature in late spring, with egg hatch and crawler activity most common in late June and July.

Striped Pine Scale (Toumeyella pini)1

Striped pine scale, males on needles. WHITNEY CRANSHAW

hosts Various pines, particularly Scotch pine Damage Feeding stunts development of new growth and can induce premature needle drop. Heavy infestation may kill branches and severely detract from tree appearance. Striped pine scale produces abundant amounts of sticky honeydew, which attracts scavenging wasps in fall and promotes sooty mold growth. Distribution Widely distributed east of the Rockies, particularly in more northern areas. Appearance The adult female is hemispherical, about ¼ inch in diameter, and attached to twigs. General coloring is dark brown or black with reddish brown or cream-colored mottling. Males are smaller and more elongate and often develop on needles. Life History and Habits Striped pine scale spends the winter in the form of fertilized females on twigs. Feeding resumes in spring, at which time the insects become greatly enlarged with maturing eggs. Abundant amounts of sticky honeydew are produced at this time. Eggs may begin to hatch in the female beginning in late May or early June, and peak activity of crawlers occurs over about one month. Females usually settle at the base of needles, males on the needles. Adult males emerge to mate with the females in late summer.

380

A

A. Magnolia scales. DAVID SHETLAR

B. Magnolia scale females. DAVID SHETLAR

C. Magnolia scale males. DAVID SHETLAR

D. Magnolia scale crawlers. DAVID SHETLAR

B

E. Magnolia scale,

young nymphs.

JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Terrapin scale. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH WSERVICE, BUGWOOD.ORG

C

G. Calico scales on leaf. DAVID SHETLAR

H. Calico scales on branch. DAVID SHETLAR

I. Striped pine scale,

mature females. WHITNEY CRANSHAW

J. Striped pine scale,

D

E

F

G

crawlers.

WHITNEY CRANSHAW

H

I

J

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

SOFT SCALES OBSERVED PRIMARILY ON TWIGS

Related and Similar Species Pine tortoise scale (Toumeyella parvicornis) is also associated with pine. Its biology appears similar to that of striped pine scale, and it shares many hosts. Females are slightly smaller than striped pine scale and more uniformly colored, with no cream-colored markings. Irregular pine scale (T. pinicola) is common on pine, particularly Monterey pine, in California. In the eastern U.S., tuliptree scale (T. liriodendri) is a common pest of yellowpoplar (tuliptree) and magnolia. This is the largest soft scale in North America, with some mature females swollen with eggs reaching ⅝ inch in length. Thinning of foliage, dieback of twigs, and serious honeydew problems may occur with this insect. Two generations per year appear to occur in southern areas of its range. Small spruce bud scale (Physokermes hemicryphus)1 develops on the twigs of spruce, infesting primarily lower branches. The mature females are reddish brown and globular and closely resemble a plant bud scale in size and shape. Spruce bud scale spends the winter as small first-instar nymphs on needles of spruce. In midspring they resume activity and move to the twigs where they settle and feed and excrete honeydew. Females become full grown and swollen with eggs in June, and eggs hatch in late June and July. There is one generation per year. 1

Hemiptera: Coccidae

Cottony Maple Scale (Pulvinaria innumerabilis)1 hosts Maple, honeylocust, hackberry, linden, and many other hardwoods Damage Nymphs suck sap from leaves in early summer; late stages are found on twigs and small branches. Large amounts of honeydew may be excreted by stages in late development. Distribution Cottony maple scale is found throughout the U.S. and southern Canada. Appearance Cottony maple scale is one of the most conspicuous of the soft scales. Adult females may swell to more than ¼ inch in diameter when producing a ⅜-inch-long, white, cottony ovisac that covers the eggs as they are laid. Nymphs are flattened, broadly oval, and translucent and are found on leaves. Overwintering females look like small dark warts. They subsequently swell dramatically as eggs mature. Life History and Habits Cottony maple scale spends the winter as mated adult females on twigs and branches. They resume feeding in spring and mature their eggs, which are contained in a large cottony egg sac somewhat resembling a small marshmallow. Eggs hatch from mid-June through July. The newly hatched crawlers settle on the underside of leaves, usually near the midrib. At the end of the season, tiny winged males emerge and mate with the females, which subsequently migrate to twigs. Related Species Two related species have adult stages and produce large ovisacs that occur on leaves. Cottony maple leaf scale (Pulvinaria acericola) develops on maple, dogwood, and holly in the eastern U.S. and southern Canada. Cottony camellia scale (P. floccifera), sometimes known as “cottony taxus scale,” is most commonly found on holly, camellia, jasmine, and yew.

382

A

B

C A. Comparison of pine tortoise scale (left) and striped pine scale (right). WHITNEY CRANSHAW

B. Pine tortoise

scale with crawlers. DAVID SHETLAR

C. Pine tortoise

scales before swelling with eggs. DAVID SHETLAR

D. Tuliptree scale,

mature females.

D

E

F

G

DAVID SHETLAR

E. Tuliptree scales

being tended by ants. DAVID SHETLAR

F. Small spruce

bud scale.

DAVID SHETLAR

G. Cottony maple

scale, mature female. DAVID SHETLAR

H. Cottony maple

scales infestation of a maple branch. JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Cottony maple scale nymph on leaf. WHITNEY CRANSHAW

J. Overwintering

stages of cottony maple scale on twigs. DAVID SHETLAR

H I

J

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

SOFT SCALES OBSERVED PRIMARILY ON TWIGS

Other Soft Scales Associated Primarily with Twigs Mature females of the black scale (Saissetia oleae)1 are generally round, dark brown, and attached to twigs. Prior to becoming fully extended the scale cover has an H-shaped hump, a characteristic share with the hemispherical scale (following). It has an extremely wide host range, including Ficus, citrus and other fruits, holly, pittosporum, rose, olive, and peppertree. Black scale can survive year round outdoors in the southern U.S., typically producing two generations, and highest populations often occur in more humid sites. Elsewhere black scale can be a common greenhouse/houseplant pest. Closely related and of similar appearance is hemispherical scale (S. coffae), which is also a common scale associated with indoor plants. Ferns, Chlorophytum, and Diszygotheca are favored hosts, but hemispherical scale has a very wide host range. The full-grown female is slightly larger than brown soft scale, dark brown, and rounded (helmet-shaped). Early-stage nymphs are semitranslucent and yellowish. As the female matures a series of ridges that form an H-shape is usually evident. Size of this scale can vary considerably on different types of host plants. Females can lay up to 600–700 eggs underneath their scale covering. After egg laying, the mother dies and the scale covering become a rounded cap that protects the eggs. As the eggs hatch the greenish-brown crawlers emerge to move about the plant to find a suitable feeding site. Once settled, they usually remain in place for the remainder of their lives, although the two nymphal stages retain mobility. The entire life cycle, from egg laying to the adult stage, is fairly long, typically taking about 2–3 months. Nigra scale (Parasaissetia nigra)1 has a wide host range but is reportedly most damaging to Japanese aralia, English ivy, English holly, oleander, orange-berry pittosporum, and hibiscus. Full-grown females are dark black and smoothly hemispherical, lacking the raised H-shaped hump of black scale. Nigra scale occurs outdoors in areas of California and Florida and is widespread elsewhere on houseplants. Brown soft scale (Coccus hesperidum)1 is often the most common soft scale associated with indoor plants. Stages occur on both leaves and stems. This scale is discussed in more detail on page 266. Wax scales (Ceroplastes spp.)1 are a large group of scales found in tropical areas worldwide. A few species develop outdoors in parts of the southern U.S., and they are sometimes moved elsewhere on indoor plants. This group of scales is notable in having a thick coating of whitish wax, often with pinkish or grayish tones. Unusual projections of the wax covering are common and characteristic of many species. Wax scales can excrete large amounts of honeydew. Most wax scales have a wide host range. Blueberry, camellia, citrus, fig, Eugenia, Chinese holly, jasmine, mulberry, pear, persimmon, plum, and quince are among the hosts of Indian wax scale (C. ceriferus). This species also occurs on leaves, particularly the upper surfaces of holly leaves. Florida wax scale (C. floridensis) is most common on citrus, holly, Laurus, Nerium, Schefflera, and Psidium. Barnacle scale (C. cirripediformis) is found on gardenia, citrus, euonymus, and several other ornamental plants. Host plants of red wax scale (C. rubens) include citrus, gardenia, palms, Persea, Schefflera, Aglaonema, and Dieffenbachia. This species is apparently restricted to Florida. Citrus, holly, and Dizygothela are hosts of Chinese red scale (C. sinensis).  Hemiptera: Coccidae

1

384

A

B

C

D

E

F

A. Black scale. US NATIONAL COLLECTION OF SCALE INSECTS PHOTOGRAPHS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

B. Hemispherical scale, mixed stages. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Hemispherical scale crawlers. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G

D. Brown soft scale. DAVID SHETLAR

E. Indian wax scale. DAVID SHETLAR

F. Red wax scale. J. A. DAVIDSON, UNIVERSITY OF MARYLAND, BUGWOOD.ORG

G. Barnacle scale. DAVID SHETLAR

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

MARGARODID SCALES ASSOCIATED PRIMARILY WITH TWIGS Margarodid scales (Margarodidae), also known as the giant coccids, are primarily tropical and subtropical species; about 40 species occur in North America. They typically produce eggs in a loose sac of cottony wax. Immature forms may look substantially different from adults.

Cottony Cushion Scale (Icerya purchasi)1 hosts A wide range of trees and shrubs, including citrus, maple, nut trees, pittosporum, nandina, Boston ivy, and several stone fruits (Prunus spp.). Damage Damage is caused primarily by removal of sap, which can produce premature yellowing and leaf and fruit drop. Cottony cushion scale also produces large amounts of sticky honeydew. Distribution A tropical/subtropical species accidentally introduced into North America. It is found in southern California, Arizona, the Gulf States, and north to Virginia. Greenhouse infestations may occur throughout North America. Appearance Adult females are about ¼ inch and mottled rusty red with black legs and antennae. They are usually covered with white wax and produce a conspicuous, fluted wax egg sac that may extend ⅜ inch. Life History and Habits Eggs are laid in the egg sac and hatch in 3–8 weeks depending on the season. All immature stages are capable of crawling about the plant, and they tend to be found first on leaves and twigs. Females nearing maturity often migrate to larger branches and trunks where they feed little if at all. The female produces eggs over about 2 weeks. An entire life cycle can be completed in about 2–3 months, longer with cool weather. In northern areas of the range only two or three generations are produced annually; many more can be produced in warmer areas or indoors.

Other Margarodid Scales Sycamore scale (Stomacoccus platani)1 develops on sycamore, moving between woody parts of the plant to leaves and back, a process repeated over the course of 3–5 generations in a year. Twig dieback, leaf distortion, and yellowing are symptoms of heavy infestation. Pinyon needle scale (Matsucoccus acalyptus)1 is an occasional pest of pinyon in the southwestern U.S. Feeding by adult females and nymphs causes needles to turn yellow and prematurely fall. The stage most commonly observed is the second-instar nymph (“bean stage”), found attached to needles through winter and in early spring. Adult females that emerge from this stage are black, armored, mobile scales, about 1⁄16 inch long. These migrate to the trunk in spring, where they settle then produce large numbers of eggs within a loose egg sac of wax. The nymphs that subsequently hatch then move to the needles, where they feed throughout spring and summer. Hemiptera: Margarodidae

1

386

A

B

C D E

A. Cottony cushion scale, mature female with egg sac.

F

DAVID SHETLAR

B. Cottony cushion scale, mixed life stages on twigs. DAVID SHETLAR

C. Cottony cushion

scale eggs.

LORRAINE GRANEY, BARTLETT TREE EXPERTS, BUGWOOD.ORG

D. Cottony cushion scale, migrating nymph. LORRAINE GRANEY, BARTLETT TREE EXPERTS, BUGWOOD.ORG

E. Cottony cushion

scale, mixed life stages on leaves. DAVID SHETLAR

F. Pinyon needle

scale adult stages massed on trunk. WHITNEY CRANSHAW

G

G. Pinyon needle

scale, overwintering “bean stage” on needles. WHITNEY CRANSHAW

H. Sycamore scale,

stages on leaves.

US NATIONAL COLLECTION OF SCALE INSECTS PHOTOGRAPHS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

H

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

ARMORED SCALES THAT DEVELOP PRIMARILY ON SMALL BRANCHES AND TWIGS The armored, or “hard,” scales (Diaspididae family) are small (1⁄20–⅛ inch) insects that secrete a hard protective cover that encloses the insect. Only during the brief crawler stage (instar 1) that occurs just after egg hatch are armored scales mobile. After the first molt they lose their legs and remain in place for the remainder of their lives. In a settled developing armored scale, only the mouthparts extend through the covering. What remains visible is the expanded covering, known as the test, which covers the scale body and later encloses the eggs. By maturity most armored scales have a cover comprising three parts: the shed exoskeletons (exuviae) produced by both the first and second stage nymphs, and the waxy test. Many armored scales produce males, and these are very much different in form from the females. The male test is usually much smaller, more slender, and often of different color that what is produced by the female, which can give the appearance of two different scales infesting a plant. Winged adult males emerge which then seek females for mating; however, not all armored scales produce males and some that do have strains that reproduce asexually without males. The eggs that are produced are laid within the protective cover of the mother scale, which dies after eggs are laid. When eggs are ready to hatch they escape through a small slit on the underside of the covering. Armored scales feed directly on plant cells rather than on sap from the phloem, the latter being the habit common to soft scales. Armored scale do not excrete honeydew, but areas of the plant on which armored scales feed may be killed, producing symptoms such as chlorotic spotting on foliage and twig dieback. Approximately 200 species of armored scales are known to occur in North America, with additional new species often being accidentally introduced on infested plant materials. Some develop primarily on foliage, and these are discussed on pages 270– 275. Others develop exclusively on stems and branches, whereas others can be found on both parts of plants.

Oystershell Scale (Lepidosaphes ulmi)1 hosts A wide range of trees and shrubs. Aspen, ash, cotoneaster, dogwood, maple, willow, and lilac are among the most commonly damaged landscape plants. Apple and occasionally other fruit trees may be hosts. Damage Oystershell scale attaches itself to twigs, branches, and trunks. It sucks sap from adjacent cells, often killing tissue around the feeding site. Heavy infestations produce stunting, foliage yellowing, and bark cracking. Dieback of twigs and branches is a common result of oystershell scale injury, and infested trees are often so weakened they succumb to fungal cankers. Distribution Oystershell scale is of European origin but now present throughout North America, being most damaging in the northern U.S. and southern Canada. Appearance The oystershell scale has a light to dark brown wax cover that is elongate and resembles the shape of an oyster’s shell. Some banding may be observed or, on some hosts, the scale is covered with a fine powder of wax that largely obscures marking. Immature stages are golden brown and they darken with age. Life History and Habits Oystershell scale winters as whitish eggs underneath the scale covering of the mother. When eggs hatch in mid- to late spring, pale yellow crawlers move over the bark in search of sites where they can feed. If successfully established, the crawlers will molt in about a week, losing their legs but creating the protective wax cover. In most areas one generation per year is produced, with adults maturing in midsummer and producing the overwintering eggs; however, the ‘lilac strain’ associated with maple and lilac in the Mid-Atlantic region has two generations. Most oystershell scales present in North America do not produce males. 388

A B

C

A. Oystershell scales densely crusting the surface of an aspen trunk. WHITNEY CRANSHAW

B. Oystershell

scale flipped to expose eggs. WHITNEY CRANSHAW

C. Cytospora canker

fruiting bodies developing on limb heavily damaged by oystershell scale. WHITNEY CRANSHAW

D. Oystershell scales crawlers next to cover of a mother scale.

D

WHITNEY CRANSHAW

E. Newly settled

oystershell scales next to cover of a mother scale. WHITNEY CRANSHAW

E

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

ARMORED SCALES THAT DEVELOP PRIMARILY ON SMALL BRANCHES AND TWIGS

Other Armored Scales Associated with Twigs and Branches Euonymus scale (Unaspis euonymi)1 can be common on leaves and stems of evergreen shrub varieties of Euonymus. Females, which are shaped like oystershells and generally brown, tend to be most common on twigs. Males, which produce a fuzzy white, elongate cover tend to be more common on leaves. The most common symptoms of infestations are yellowish or brown spots on leaves produced at feeding sites. High populations on stems can cause branch dieback. Winter is spent as a mature, fertilized female that produces eggs in early spring. Yellow-orange crawlers subsequently emerge over a period of few weeks, settle, and develop over the course of about a month. Adult males emerge and mate with females in early summer, followed by a second cycle of egg hatch and crawler dispersal in midsummer. Three to five generations per year may occur in southern areas of the range. Scurfy scale (Chionaspis furfura)1 develops on trunks and branches of various deciduous trees and shrubs, with aspen, cottonwood, and willow among the most common hosts. Apple, hawthorn, mountain-ash, and Prunus are less commonly infested. Elm scurfy scale (C. americana) is found in the eastern U.S. associated with certain deciduous trees and shrubs, including elm, privet, and hackberry. Japanese maple scale (Lopholeucaspis japonica)1 develops primarily on some maples and hollies. San Jose scale (Quadraspidiotus perniciosus)1 develops on a wide variety of trees and shrubs in the rose family (Rosaceae), including apple, rose, pyracantha, cotoneaster, and crabapple. Areas around the feeding site are damaged, often producing a localized discoloration, and heavily infested branches can be killed. San Jose scale may also develop on fruit, producing reddish spotting. San Jose scale usually overwinters as second instar (“black cap”) nymphs. They remain dormant until sap flows in the spring, and then continue to feed and develop. By the end of April, adult forms are usually present. The adult males emerge from the scale cover as tiny, winged, gnatlike insects. They mate with the females, which may subsequently produce eggs that hatch under the cover. The newly emerged crawlers move about the plant and usually settle to feed within the first 24 hours. After settling they initially produce a circular, dirty white cover, known as the “white cap” stage. Later stages produce coverings that are gray-brown and develop a more pronounced yellow nipple in the center. Coverings of the male scales are considerably smaller and much more elongate. The body of the female scale insect underneath the covering is yellow. During the growing season, San Jose scale develops and matures over a month or so and repeats the life cycle. Two generations are typical in northern areas, but near continual development in southern areas occurs, with up to 5 generations annually. As individual females can produce well over 100 eggs over a period of 6 weeks, generations soon overlap and all stages are present during much of the season.

390

A B

A. Mixture of male and female euonymus scales on twig.

C

DAVID SHETLAR

B. Euonymus scales heavily

infesting leaves and branches. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Scurfy scale on aspen. DAVID LEATHERMAN

D. Scurfy scales with crawlers present. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. San Jose scales. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. San Jose scale with cover flipped to expose an adult female. DAVID SHETLAR

G. White cap stage of San Jose

scale.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

D

E

F

G

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

ARMORED SCALES THAT DEVELOP PRIMARILY ON SMALL BRANCHES AND TWIGS Walnut scale (Quadraspidiotus juglansregiae)1 is a common species associated with deciduous trees and shrubs, including ash, birch, linden, and maple. Despite its name, the only walnut (Juglans) species that hosts this insect is Persian walnut. Walnut scale is generally distributed throughout North America. It feeds on twigs, branches, and sometimes trunks, causing reduced vigor during heavy infestations with associated thinning and yellowing of foliage. Walnut scale is generally circular in form, similar in appearance to San Jose scale. It can be distinguished by having a more orange or orange-red body, and the top of the covering (exuviae) is sunken at the center. Winter is spent as partially developed scales in the second instar, similar to San Jose scale; however, only one generation is produced annually, with eggs produced over an extended period by the overwintered females. California red scale (Aonidiella aurantii)1 affects many ornamental plants (acacia, boxwood, eugenia, euonymus, magnolia, mulberry, palm, podocarpus, privet, rose) and can be a serious pest of citrus. It is found outdoors in warmer areas of the southern U.S. and is a common greenhouse pest. Adult females are round, reddish orange, and have concentric rings on the cover. Young stages produce some cottony filaments of wax around their body; later stages form the more solid cover. Willow scale (Diaspidiotus gigas)1 is associated with poplars, aspens, and willows, developing primarily on trunks and larger branches. They blend in well on bark and can be very difficult to see, but they often produce a noticeable bubbling of the bark surface. Other scales that similarly produce a round cover and are well camouflaged on the bark of their hosts include obscure scale (Melanaspis obscura)1 associated with oaks, particularly pin oak, and gloomy scale (M. tenebricosa), associated with silver and red maples. Latania scale (Hemiberlesia lataniae)1 is common in the Gulf States and present in southern California. It has a wide host range, with palm and schefflera among the common hosts. It is found on both leaves and twigs. The covering is gray-brown and broadly oval with an off-centered exuviae, giving it a tilted appearance. The closely related greedy scale (H. rapax) is similar in appearance. It gets its name from its wide host range, which includes citrus, ivy, acacia, boxwood, cactus, ceanothus, fruit trees, holly, laurel, magnolia, palm, peppertree, pittosporum, pyracantha, and redbud. Bermudagrass scale (Odonaspis ruthae)1 is commonly associated with bermudagrass but is rarely damaging. It produces a circular or somewhat elongated white covering and concentrates around the nodes of plant stems. 1

Hemiptera: Diaspididae

392

A

B

C D

A. Walnut scales.

D. Willow scale on aspen.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

B. California red scales being

E. Obscure scales.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

F. Gloomy scales.

attacked by a parasitic wasp. C. Overwintered nymph

of willow scale.

WHITNEY CRANSHAW

E

F G

DAVID SHETLAR

LORRAINE GRANEY, BARTLETT TREE EXPERTS, BUGWOOD.ORG

G. Lantania scales. JIM KALISCH, UNIVERSITY OF NEBRASKA

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

KERMES, PIT, AND FALSEPIT SCALES Kermes scales (Kermesidae family) are sometimes known as “gall-like scales” because of their large size and globose form. All are associated with oak. Winter is spent as first-stage nymphs on the bark of branches or trunks. These later move to new growth, completing development on twigs. Females swell greatly when producing eggs and become smooth and ball-like. Nymphs and developing females produce copious honeydew. Eggs of the pin oak kermes (Allokermes galliformis)1 hatch in October and early November, but life cycles of other species may differ in this feature. Nanokermes pubescens1 is a common eastern U.S. species whose eggs begin to hatch in July. Eggs of A. kingi are laid in summer but hatch in September. Most kermes scales cause little injury to oaks, although some may contribute to twig dieback, and their large size attracts attention. A situation where more serious damage is produced occurs with pin oak kermes in association with a bacterium (Lonsdalea quercina), resulting in a disease of red oaks known as “drippy blight.” Pit scales (Asterolecaniidae family) feed on developing twigs, causing a raised ridge to form around the insect. Most commonly damaging is golden oak scale (Asterolecanium variolosum)2 and related species that occur on oak (A. quercicola, A. minus) that can seriously reduce growth and cause branches to die prematurely. Mature females of golden oak scale are hemispherical and yellow-green to brown with a waxy fringe around the margin. They spend the winter as mature females that resume feeding in spring. Eggs hatch over a period of several months, with peak crawler activity in early summer. The crawlers do not move far from the mother scales, settling on first-year wood of twigs. One generation is produced per year. Although pit scales on oak are most commonly encountered, some 29 pit scale species occur in North America, many associated with other plants. Holly pit scale (Asterolecanium puteanum) is found on various hollies in the eastern U.S. as far west as Texas. Pitmaking pittosporum scale (A. arabidis) is present on mockorange, privet, and green ash in many of the states of the East and West coasts. Bamboo scale (A. bambusae) is an introduced species occasionally found on bamboo but apparently causes little damage. Yucca is host for A. agavis. The pit scale with the widest host range is oleander pit scale (A. pustulans), which develops on many plants, including fig, lantana, magnolia, oleander, bougainvillea, and mulberry. The falsepit scales (Lecanodiaspididae family) are represented by five species in North America, all in the genus Lecanodiaspis. Common falsepit scale (L. prosopidis)3 is typical. It lives on twigs and small branches of various deciduous trees and shrubs, including ash, azalea, mulberry, oak, and honeylocust. Feeding induces pits or welts to form, distorting the tree and contributing to dieback of branches and twigs. Full grown, this species appears rather domelike with a thick waxy white cover. Egg hatch and crawler activity occur around May. Lobate lac scale (Paratachardina pseudolobata)4 is an introduced species that has spread throughout south Florida. It can build up dense colonies on twigs and small branches of susceptible plants and produce large amounts of honeydew, which supports sooty mold growth. Wax-myrtle, coco-plum, mango, star-fruit, lychee, and ficus are among the most susceptible species. Heavy infestations can result in significant branch dieback. 1

Hemiptera: Kermesidae; 2 Hemiptera: Asterolecaniidae; 3 Hemiptera: Lecanodiaspididae; 4 Hemiptera: Kerridae

394

A C D

B E

F

G

A. Pin oak kermes. WHITNEY CRANSHAW

B. Eggs, egg shells and crawlers of

pin oak kermes. WHITNEY CRANSHAW

C. Nymphs of pin oak kermes

settled at growth ring.

H

I

WHITNEY CRANSHAW

D. Bacterial ooze of Lonsdalea

quercina at feeding site of pin oak kermes. WHITNEY CRANSHAW

E. Twig die-back due to drippy

blight, a condition resulting from combined effects of a kermes scale and a bacterium. WHITNEY CRANSHAW

J

F. Golden oak scales. DAVID SHETLAR

g. Stem pitting by oleander pit

scale.

DAVID SHETLAR

H. Oleander pit scales. DAVID SHETLAR

I. Common falsepit scale. WHITNEY CRANSHAW

J. Lobate lac scale. DOUG CALDWELL, UNIVERSITY OF FLORIDA

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

SPITTLEBUGS Spittlebugs are closely related to the leafhoppers but tend to be somewhat broader in form. They are similarly small, with adults typically about ¼ inch when full grown. What is uniquely characteristic, however, is the spittle mass the nymphs produce after they begin to feed. This is produced from excess excreted fluids (spittlebugs can suck fluids from the xylem), combined with mucilaginous fluids into which air bubbles are introduced. The function of the spittle mass is thought to protect the nymphs from predators and from drying. The great majority of spittlebugs are associated with woody plants, but some feed on herbaceous plants for part of their life cycle. Meadow Spittlebug (Philaenus spumarius)1 can be found on an extremely wide range of plants, including strawberry, various flowers, and legumes, both wild and cultivated. Little damage usually occurs from removal of sap by feeding, although some stunting of growth may occur. Significant damage to strawberry and alfalfa has been reported but is rare. The prominence and appearance of the spittle mass often attract attention and concern. It is present in much of the U.S., excluding southwestern areas, but most common in the Northeast and Pacific Northwest. Adults are rarely observed but are about ¼ inch long, straw-colored to dark brown. Nymphs are pale green and found in spittle masses. Eggs are laid in small masses among crevices of the host plants. Eggs hatch in spring, and the nymphs feed primarily on stems, quickly producing a large frothy spittle mass. They become full grown in late spring, and the winged adults disperse to feed on a wide variety of plants through the summer. Eggs are laid in fall, and one generation is produced per year. Twolined Spittlebug (Prosapia bicincta)2 is associated primarily with warm-season grasses, particularly centipedegrass and bermudagrass. Adults also feed on holly and, much less commonly, redbud and cherry. It occurs in much of the eastern half of the U.S. and is particularly common in the southeastern states. Nymphs and adults feed on grass blades, removing sap. More significant effects seem to result from toxic effects of saliva, which can cause leaf spotting and sometimes death of blades. Adults feeding on holly can produce leaf spotting and distortion. The adults are broadly oval to wedge-shaped, about ⅓ inch, and generally dark brown or black. Most have red or orange lines across the wings, although these may be absent. Legs and eyes are red as well. Nymphs, which are found in a spittle mass in the crown of the plant, generally resemble adults but lack wings and are creamy yellow. Winter is spent in the egg stage among grass plants, and egg hatch occurs in late spring. The nymphs settle at the base of plants and begin to feed, subsequently producing a spittle mass. They repeatedly molt as they develop, becoming full grown in about a month. Adults may feed on nearby woody plants, notably holly, as well as grasses. A second generation occurs in the southeastern U.S., one generation in more northern areas.

396

B

A

C D E

F

A. Meadow spittlebug spittle mass. WHITNEY CRANSHAW

B. Meadow

spittlebug adult. DAVID SHETLAR

C. Meadow spittlebug

egg mass.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Meadow spittlebug nymphs within spittle mass. WHITNEY CRANSHAW

G

E. Twolined

spittlebug adult. DAVID SHETLAR

F. Spittle mass of

twolined spittlebug at base of grass plant. DAVID SHETLAR

G. Spittle mass of

twolined spittlebug with nymph exposed. DAVID SHETLAR

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

SPITTLEBUGS Numerous species of Clastoptera3 are found throughout North America. Juniper spittlebugs (C. juniperina, C. doeringae) can be common on juniper and arborvitae in many western states. Pecan spittlebug (C. achatina) sometimes contributes to twig dieback of pecan. Alder spittlebug (C. obtusa) feeds on various shrubs and trees, including hickory, birch, and alder. Dogwood spittlebug (C. proteus) is common on dogwood and Vaccinium in the Midwest. Clastoptera delicata is associated with stinking rabbitbrush and sage in the western states. Saratoga spittlebug (Aphrophora saratogensis)1 occurs in the eastern half of the U.S. and can be a damaging insect on certain conifers, particularly Scotch, red, and jack pines. Nymphs (and their associated spittle masses) develop on a wide variety of shrubs and herbaceous plants, notably sweetfern. Adults then migrate to conifers and feed on shoots. The saliva of the Saratoga spittlebug is toxic to some plants, producing a pocket of damaged and dead tissue at the feeding site. Wilting beyond the feeding site may occur when the insects are abundant enough to seriously damage twigs. Several related species are found in North America. The pine spittlebug (Aphrophora parallela) develops on pines in the Midwest. Aphrophora cribrata can be common on eastern white pine; in the northwestern states the western pine spittlebug (A. permutata) is the most common representative.  Hemiptera: Aphrophoridae; 2 Hemiptera: Cercopidae; 3 Hemiptera: Clastopteridae

1

top left: Pecan spittlebug. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

left: Twig dieback due to feeding by Saratoga spittlebug. MINNESOTA DEPARTMENT OF NATURAL RESOURCES, BUGWOOD.ORG

above: Pine spittlebug. DAVID SHETLAR

398

A B

C D

F

A. Adult of a juniper spittlebug. WHITNEY CRANSHAW

B. Spittle mass of dogwood spittlebug. DAVID SHETLAR

C. Spittle mass with nymph of juniper

spittlebug.

WHITNEY CRANSHAW

D. Adult dogwood spittlebug. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

E. Adult alder spittlebug. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Saratoga spittlebug adult. DAVID SHETLAR

E

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

PLANTHOPPERS Three families of insects are collectively known as planthoppers: Flatidae, Acanaloniidae, and Fulgoridae. They are most abundant in the tropics, but around 60 North American species are concentrated in the eastern half of the continent. They typically feed on stems, less commonly on leaves, and many excrete noticeable amounts of honeydew; however, with very few exceptions, damage is negligible. Most planthoppers also produce wax, which may be in the form of very conspicuous long threads and often attracts attention to these small insects. Both adults and nymphs are capable of making short jumps. Adults of both the flatid leafhoppers and acanaloniid planthoppers are similar in size and shape, and somewhat resemble a small moth. The body is wedge-shaped and most species are green to a bluish-brown. Citrus flatid planthopper (Metcalfa pruinosa)1 is a common species ranging from Florida and Texas to Ontario. Despite its common name, it can develop on a great many types of plants aside from citrus. Additional hosts include some stone fruits (cherries, peach), some small fruits (grape, raspberry), and a large number of trees and shrubs (azaleas, holly, privet, viburnum, maples, dogwood, magnolia and others). One generation is produced annually, with winter spent as eggs on the bark of twigs. Nymphs are very flat and A fulgorid planthopper. covered with waxy threads and may be seen feeding in a line DAVID SHETLAR on stems. In the southern area of its range, nymphs are present in spring, with peak numbers of adults often noted in June or early July. In northern areas nymphs are present into summer with adults most abundant in late summer. Twostriped planthopper (Acanalonia bivittata)2 can be a common species in much of eastern North America. Adults are usually bright green, with a pair of prominent stripes, but pink forms also occur. It has a very wide host range that includes many types of woody plants as well as some herbaceous plants. Nymphs have rounded bodies with tufts of waxy threads extending from the abdomen. Adults appear in May or June and are usually present through summer. Lycorma delicatula,3 sometimes called the “spotted lanternfly,” was first detected in Pennsylvania in 2014. This large fulgorid planthopper is a native of Asia and the largest species of planthopper currently found in the U.S. Adults are an inch or more in length and have a wing span of more than 2 inches. Adults appear gray with distinctive black spots and netting on the forewings; however, when they take flight, bright red to orange hindwings are revealed. Nymphs are first red and black, covered with white spots, but they eventually turn completely black with white spots. Ailanthus (tree-of-heaven) is a highly favored host damaged by feeding wounds on branches and trunks. More than 70 other plants are also hosts, and spotted lanternfly is considered a particular threat to grapes and fruit trees. About 16 other native species of fulgorid planthoppers are also present in North America but are infrequently observed as most are dull-colored, and nymphs do not produce conspicuous wax threads. 1

Hemiptera: Flatidae; 2 Hemiptera: Acanaloniidae; 3 Hemiptera, Fulgoridae

400

A

B

C D E

F

G

A. A flatid planthopper, Metcalfa pruinosa. DAVID CAPPAERT, BUGWOOD.ORG

B. Nymph of the flatid

planthopper, Metcalfa pruinosa. DAVID CAPPAERT, BUGWOOD.ORG

C. A flatid planthopper,

Ormenoides venusta.

DAVID CAPPAERT, BUGWOOD.ORG

D. An acalonid planthopper,

nymph.

DAVID CAPPAERT, BUGWOOD.ORG

H

E. An acalonid planthopper,

adult.

DAVID SHETLAR

F. Acalonid planthopeprs

developing on a twig. DAVID SHETLAR

G. Spotted lanternfly adult. LAWRENCE BARRINGER, PENNSYLVANIA DEPARTMENT OF AGRICULTURE, BUGWOOD.ORG

H. Spotted lanternfly nymph. LAWRENCE BARRINGER, PENNSYLVANIA DEPARTMENT OF AGRICULTURE, BUGWOOD.ORG

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

TREEHOPPERS Treehoppers are distinguished by a prominent enlargement of the segment behind the head (pronotum), which extends shieldlike over the head and much of the abdomen. This is often further enlarged to produce spiny or hornlike projections, leading to the term “thorn bugs” applied to some species. The nymphs often have spines running along the back. Treehoppers are infrequently encountered by gardeners. Most species have fairly innocuous habits, and the primary plant injuries often occur during the course of depositing eggs into stems and twigs. The majority of treehoppers feed on trees and shrubs; a few feed on herbaceous plants such as Canada thistle and sunflower.

Buffalo Treehopper (Stictocephala bisonia)1 hosts Eggs are laid on apple, peach, ash, elm, and many other woody plants. Nymphs feed on a variety of herbaceous and woody plants, including clovers and goldenrods. Damage Buffalo treehopper causes very little, if any, injury to plants in the course of feeding. Plant injuries are produced during egg laying, when eggs are inserted into slits made in the upper surface of twigs. Extensive egg laying can cause damaged twigs to become scabby and somewhat distorted. Distribution Throughout the U.S. and much of Canada; this is the most widely distributed and familiar North American treehopper. Appearance Adults are generally triangular shaped, with the sides of the front developed into small points, somewhat resembling a miniature bison. Buffalo treehopper is grassy green and about ⅜ inch long. Nymphs are somewhat brighter green with a row of ridges along the back. Life History and Habits Buffalo treehopper overwinters in the egg stage, and eggs are inserted as small groups under the bark of twigs. The eggs hatch in late spring, and the nymphs drop to the ground to feed on grasses and broadleaf weeds around the base of trees on which eggs were laid. Adults become full grown in late July or August. Females insert their eggs into twigs, typically laying about a half-dozen eggs within each oviposition wound. One generation is produced per year.

Other Treehoppers There are about two dozen North American species of “buffalo treehoppers” in the genera Stictocephala1 and Spissistulus,1 almost all of which are quite similar in shape and color. One of these, known as the threecornered alfalfa treehopper (Spissistilus festinus), develops on legumes in the southern states and is particularly damaging to soybean. Its primary plant injury is stem breakage, which can result when feeding punctures are concentrated in a small area and result in stem girdling. Twomarked treehopper (Enchenopa binotata complex)1 occurs commonly in many areas west of the Rockies, primarily in northern areas. Hoptree, nut trees, black locust, viburnum, redbud, bittersweet, and wisteria are among reported hosts. As with other treehoppers, twomarked treehopper inserts eggs into twigs, but it then covers these with a whitish frothy material that makes oviposition sites very conspicuous. Egg masses are often misidentified as scales. The spiny nymphs aggregate to feed at tips of branches.

402

B C

A

D E

A. Buffalo treehopper adult. WHITNEY CRANSHAW

B. Buffalo treehopper

nymph.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Threecornered

alfalfa treehopper. JOHNNY N. DELL, BUGWOOD.ORG

D. Twomarked treehoppers. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Egg masses of

twomarked treehopper. DAVID SHETLAR

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

TREEHOPPERS One of many treehopper species found on oaks, oak treehopper (Platycotis vittata)1 occurs widely throughout much of the U.S., developing on various oaks, birches, and chestnut. Feeding injuries are minor, but oviposition scars in twigs may attract attention. Large colonies of nymphs may be observed on twigs, often along with the mother. Although oaks support the greatest diversity of treehoppers, several species are commonly associated with other types of plants. Micrutalis calva1 can be a common species on honeylocust; Thelia bimaculata1 develops on black locust; Telamona reclivata is associated with basswood, and T. decorata occurs on quaking aspen. None of these are considered significantly damaging to their host. Entylia carinata1 is one of the most common treehoppers associated with herbaceous plants in eastern North America. It has a very wide host range, including dahlia, asters, and many common weeds such as sunflowers, ragweeds, and thistles. It also has a great deal of variation in coloration, with individuals of quite different patterning often present in the same group on a plant. Eggs are laid in masses on leaves, and the mother guards the eggs. Entylia carinata is a honeydew producer, and when groups occur they are often tended by ants. Umbonia crassicornis,1 often called “eucalyptus thorn bug” or “umbonia thorn bug,” is common from Central America through Florida, where the adults and nymphs commonly infest eucalyptus, acacia, and powder-puff trees. The adults are generally green with red and yellow markings. The adults have a prominent pointed development of the prothorax that gives them the appearance of a thorn, but the shape and size of this prominence vary considerably. Nymphs and adults often cluster in groups.  Hemiptera: Membracidae

1

Nymphs of Entylia carinata being tended by ants. DAVID CAPPAERT, BUGWOOD.ORG

Range of form among “thorn bugs.” LYLE J. BUSS, UNIVERSITY OF FLORIDA

404

A

B

C D

E

F

A. Adults and late-instar nymphs of oak treehopper. DAVID SHETLAR

B. Nymphs of the

treehopper Smilia camelus on red oak. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

C. The treehopper

Micrutalis calva on honeylocust. WHITNEY CRANSHAW

D. Adult of the treehopper

Smilia camelus on red oak. BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

E. Entylia carinata. SUSAN ELLIS, BUGWOOD.ORG

F. A colony of “thorn bugs.” DAVID SHETLAR

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

CICADAS Cicadas1 are some of the largest insects of the order Hemiptera in North America. Distant relatives of the more diminutive spittlebugs, leafhoppers, and aphids, they develop by sucking sap from the roots of trees and shrubs. Cicadas require several years to complete their life cycle, which in some species has synchronized emergence. At least 75 species occur in North America; some taxonomists recognize significantly more species. While cicadas are root feeders during most of their life cycle, the adults feed by sucking sap from tree branches and the females damage branches through their egg-laying process.

Periodical Cicadas (Magicicada species)1 17-year species: Magicicada septendecim, M. cassini, M. septendecula 13-year species: Magicicada tredecim, M. neotredecim, M. tredecassini, M. tredecula hosts A wide variety of deciduous trees and shrubs. Damage Injury results when females lay a series of small batches of eggs, inserting them into twigs. Small branches can be girdled and killed shortly after egg insertion. The damage also predisposes the branches to breakage and allows entry of pathogens. Surviving branches can display wounds for years. Adults feed on fluids extracted from twigs, and the nymphs similarly feed on roots, but these feeding injuries are considered minor. Periodical cicadas have unique life cycles that involve synchronized adult emergence at consistent intervals (17 years for northern broods, 13 years for southern broods). Emergence of the various periodical cicadas is staggered at the various places where they occur, which are referred to as “broods.” Emergence events can be spectacular— and noisy—often attracting considerable attention and sometimes concern. Because of their large numbers during such events, early European settlers likened then to Biblical locusts; as a result they are sometimes still incorrectly referred to as “17-year locusts.” (The term locust is properly applied to certain grasshoppers that may periodically mass and migrate). Distribution Much of the northeastern quadrant of the U.S. Appearance Adults are 1¼ to 1¾ inches, generally dark, and may have some banding. Their eyes are conspicuously red, and the wings are nearly transparent with orange veins. Life History and Habits Immature stages live on the roots of trees and shrubs, growing slowly. In the seventeenth year of their life they emerge from the soil, typically in late May and early June in the north, earlier in the south. They climb trees, buildings, and other upright surfaces. The nymphal skin is then shed, and adults shortly thereafter move to the trees. Adults feed on twigs, drinking fluid from the xylem, but appear to cause negligible injury by feeding. About 5 days after emergence, males begin to produce their loud buzzing “song” to attract females, and mating occurs in the trees. The females use their bladelike ovipositor to insert rows of eggs into twigs. Six to 10 weeks later, nymphs emerge from these eggs, drop to the ground, and dig into the soil to settle and feed on the roots. Periodical cicadas are remarkable insects that have both a much extended life cycle and synchronized adult emergence. Among the seven species of periodical cicadas, three have life cycles that extend for 17 years and four have a 13-year life cycle. Twelve broods of the 17-year cicadas (one brood is extinct) and four of the 13-year cicadas (one brood is extinct) are recognized. Adults can be expected to emerge every 17th or 13th year, respectively, and in most sites multiple species may emerge. The areas where these various broods occur is summarized in Table 1. 406

A C

B D

A. Massed periodical cicadas singing. DAVID SHETLAR

B. Periodical cicada

ovipositing in twig. DAVID SHETLAR

E

C. Eggs inserted into twig

by periodical cicada. DAVID SHETLAR

D. Twig wound made

during egg laying by periodical cicada. DAVID SHETLAR

E. Twig breakage due

F

G

to cicada oviposition wounding. DAVID LEATHERMAN

F. Tree with twig flagging

due to oviposition wounds made by periodical cicadas. DAVID SHETLAR

G. First-instar cicada

nymph.

JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Cicada nymph

exposed in soil.

H

DAVID SHETLAR

I. Mud tube produced by

periodical cicada nymph prior to emergence. DAVID SHETLAR

J. Adult periodical cicada

emerging from nymphal skin. DAVID SHETLAR

K. Adult periodical cicada

shortly after emergence from nymphal skin. DAVID SHETLAR

I

J

K

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

CICADAS Table 1. PERIODICAL CICADA BROODS, THEIR EMERGENCE YEARS, AND GENERAL LOCATIONS IN THE EASTERN U.S., 2001–2051 17-year BROODS EMERGENCE YEARS GENERAL REGION I II III IV V VI VII VIII IX X XI XIII XIV

2012 2029 2046 2013 2030 2047 2014 2031 2048 2015 2032 2049 2016 2033 2050 2017 2034 2051 2001 2018 2035 2002 2019 2036 2003 2020 2037 2004 2021 2038 1937 1954 Extinct 2007 2024 2041 2008 2025 2042

VA, WV, TN CT, MD, NC, NJ, NY, PA, VA IA, IL, MO IA, KS, MO, NE, OK, TX MD, OH, PA, VA, WV GA, NC, SC NY OH, PA, WV NC, VA, WV DE, GA, IL, IN, KY, MD, MI, NC, NJ, NY, OH, PA, TN, VA, WV CT IA, IL, IN, WI KY, GA, IN, MA, MD, NC, NJ, NY, OH, PA, TN, VA, WV

13-year BROODS EMERGENCE YEARS GENERAL REGION XIX XXI XXII XXIII

2011 2024 2037 1870 Extinct 2014 2027 2040 2015 2028 2041

AL, AR, GA, IN, IL, KY, LA, MD, MO, MS, NC, OK, SC, TN, VA FL LA, MS AR, IL, IN, KY, LA, MO, MS, TN

Other Cicadas Dog-day cicadas (Tibicen spp.)1 are the largest cicadas in North America, but they are much less commonly observed than heard. Males make loud, droning buzzing calls during midsummer. Dog-day cicadas are sometimes known as “annual cicadas,” as adults are present each season. Nymphs require 2–5 years to complete development, however, with overlapping generations allowing annual appearance. Oviposition injury by the females is usually minor. There are 31 Tibicen species native to North America and several recognized subspecies. Most occur east of the High Plains and these are usually green and black. Western species tend to be black with orange and red markings. There are 21 Platypedia1 species, all of which occur in the western states. Most widespread is Putnam cicada (Platypedia putnami), which occurs in forested areas. Adults are present in late spring, and males make a subdued clicking call. Oviposition injury is inflicted on twigs of maple, apple, crabapple, and some other woody plants, but these injuries are rarely extensive enough to attract attention. Okanagana1 is another species-rich genus (57 species) that is represented throughout most of the U.S. except the southern states. At least one species is reported to damage West Coast Christmas tree plantings.  Hemiptera: Cicadidae

1

408

A A. Masses of old nymphal

B B. Old skins of periodical

skins of periodical cicadas at base of tree.

C. Mating pair of periodical cicadas.

cicadas.

DAVID SHETLAR

DAVID SHETLAR

DAVID SHETLAR

D

E

C

F D. A dog-day cicada, Tibicen species.

G H

JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Adult dog-day

cicada, Tibicen pruinosa, emerging from nymphal skin. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Old nymphal skin of the dog-day cicada, Tibicen pruinosa. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Dog-day cicada

just after emergence from nymphal skin.

I

J

DAVID SHETLAR

H. Dog-day

cicada adult. WHITNEY CRANSHAW

I. Emergence holes

in soil produced by nymphs of Putnam cicada. WHITNEY CRANSHAW

J. An Okanagana

species of cicada. DAVID LEATHERMAN

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

TWIG WOUNDING PRODUCED BY EGG LAYING AND OVIPOSITION INJURIES Wounds in twigs and canes made during egg laying are produced by a few kinds of insects, notably treehoppers and cicadas (pages 402 and 406, respectively). Some crickets and katydids also oviposit in or on twigs, and oviposition twig injuries are best known with the tree crickets, particularly Oecanthus nigricornis and O. niveus.1 Tree crickets eat an omnivorous diet, typically including small insects, leaves, and flowers, but cause little plant injury during feeding. Damage to plants occurs during egg laying when the female inserts her eggs into the stem. Prior to laying eggs a bit of bark is chewed at the site and after eggs are laid they are capped with excrement. Areas where the eggs are laid may be weakened so they easily break, and fungal pathogens are often introduced into the wounded tissues. A row of eggs is typical of O. nigricornis; eggs are usually laid singly by O. niveus. The broadwinged katydid (Microcentrum rhombifolium)2 also lays eggs on twigs but does not insert them into the plant. Instead, they are laid flat on the twigs, and appear somewhat like overlapping fish scales. 1

Orthoptera: Gryllidae; 2 Orthoptera: Tettigoniidae

GALL WASPS ASSOCIATED WITH TWIGS AND SMALL BRANCHES Of all the insects that produce galls on woody plants, none are as numerous and diverse as the gall wasps (Cynipidae).1 More than 600 North American species occur, with the great majority present on either oaks or rose. Furthermore, the types of galls produced by these insects are often the result of tremendous changes in plant growth, producing galls of radically different form than the tissues from which they originate. The exact mechanism by which these insects can produce these unusual growth changes is still incompletely understood and quite complex. It is known that a progressing sequence of activities is involved, starting with physical and chemical changes when eggs are inserted into growing plant tissues by the adult, and continuing with chemical and physical changes induced by larval feeding. All parts of the plants may support one species of gall wasp or another: roots, branches, twigs, buds, flowers, acorns, and leaves. With few exceptions, these galls cause little if any significant damage to the plants and are primarily a curiosity. Some galls that develop on twigs and branches, however, can cause stunting and even some dieback. It is difficult to generalize about the life history of gall wasps, since there are so many variations. A few species, usually those associated with foliage, may have relatively simple life histories, involving an annual life cycle and production of a single gall type. However, many have much more complex life histories, including almost all those associated with twigs and branches. These typically involve two generations of the insect, one comprising solely females (agamic generation), the other, both sexes (sexual generation), and each of these produces a separate type of gall. The completion of both generations that make up the entire life cycle may be completed in a single season or require two or three years, depending on the species of gall wasp.

410

A

A. Egg laying wounds produced by a treehopper in a young twig.

B

WHITNEY CRANSHAW

B. Old egg laying wounds in apple twigs produced by buffalo treehopper. HAROLD J. LARSEN, COLORADO STATE UNIVERSITY

C. Egg laying wounds

produced by Putnam cicada. DAVID LEATHERMAN

D. Cicada eggs inserted into twig. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C D

E. Old egg laying wounds

produced by cicada. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Eggs inserted into a raspberry cane by tree cricket. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G. A female tree cricket. JIM KALISCH, UNIVERSITY OF NEBRASKA

E

H. Eggs of a broadwinged katydid.

F

DAVID LEATHERMAN

G H

411

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

GALL WASPS ASSOCIATED WITH TWIGS AND SMALL BRANCHES

Oak Rough Bulletgall Wasp (Disholcaspis quercusmamma)1 hosts Bur oak (Quercus macrocarpa) and swamp white oak (Q. bicolor) Damage Oak rough bulletgall wasp produces irregularly round galls on the current season’s twigs. In high populations the galls can give plants a very gnarled appearance and will stunt growth. A sweet honeydew-like material is also secreted on the surface of the gall that is highly attractive to flies, ants, bees, and wasps. Distribution Native to a broad area of north central and northeast North America; it has more broadly extended its range with the planting of its hosts. Appearance The adult insects are rarely observed and typical in form to most gall wasps: small dark nonstinging wasps with an enlarged blunt abdomen. Larval stages are found within the gall and are pale-colored legless grubs. Life History and Habits The oak rough bulletgall wasp has a life cycle that is completed in a single season but involves two distinct gall making generations. During late October and early November, females of the agamic (female only) generation emerge from the woody twig galls and lay eggs in the dormant buds. As new growth of the host plant begins in spring, the developing young transform tissues into a tiny “bud” gall that closely resembles a dormant bud. Within the bud galls are the sexual generation, males and females, and these emerge a few weeks after leaves have begun to emerge. After mating, the females move to the stems and insert their eggs into the growing shoots. Initially there is little evidence of any difference in growth but in about 6–8 weeks, swellings begin to erupt from the shoot, each of which houses a developing larva. These twiggalls continue to grow throughout the summer, producing growths of generally round form. Early stage galls are dark green to reddish brown and incompletely hardened. As the galls grow, a sweet honeydew-like fluid is secreted on the surface which becomes highly attractive to bees, wasps, flies, and ants. As the larvae mature and ultimately pupate, all within the center of the gall, the tissues lignify and harden and the sugary secretions cease. When the oak rough bulletgall wasp is ready to emerge, the adult chews a circular exit hole in the side of the gall.

Related Species Several other Disholcaspis species produce twiggalls on oaks. The general form of these galls is generally rounded, but some may be flattened and others are pointed. An unusual habit associated with Disholcaspis is that the galls they induce often secrete honeydew-like fluids that are attractive to ants and other insects and may allow growth of sooty molds. The various scrub oaks in the western states support numerous species. Valley oak (Quercus lobata) and Oregon oak (Q. garryana) in California support D. eldoradensis, which produces a round twiggall that also secretes honeydew; D. coloradensis is associated with Gambel oak (Q. gambellii) in the southern Rockies and also produces galls that have some associated honeydew; the “dried peach gall wasp” D. simulata occurs on leather oak (Q. durata); D. mamillaria is found on blue (Q. douglassi) and inland scrub oak (Q. berberidifolia); D. plumbella produces a beaklike gall on inland scrub oak; D. canescens produces a gall on blue oak that is notable for the honeydew fluids it secretes. On live oak (Quercus virginiana) in Florida, D. quercusvirens has life history similar to that of the rough bulletgall wasp. Common in eastern North America in association with white oaks is D. quercusglobulus, which produces a smooth round twig gall.

412

A

B

C

D E A. Twiggalls produced by oak B. Spring budgall produced by

E. Baldfaced hornet and bumble flower beetles visiting sweet ooze of oak rough bulletgalls.

WHITNEY CRANSHAW

F. Adult oak rough bulletgall

rough bulletgall wasp. WHITNEY CRANSHAW

oak rough bulletgall wasp.

C. Oak rough bulletgall wasp

ovipositing into spring growth twig. WHITNEY CRANSHAW

D. Honeydew oozing from

F

twiggalls produced by oak rough bulletgall wasp. WHITNEY CRANSHAW

G

WHITNEY CRANSHAW

wasp on twiggall. WHITNEY CRANSHAW

G. Stunting of growth by bur

oak that is regularly sustains high numbers of oak rough bulletgalls (left) versus oak that is lightly galled. WHITNEY CRANSHAW

H. Bulletgall on Gambel oak produced by a Disholcaspis species. WHITNEY CRANSHAW

H

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

GALL WASPS ASSOCIATED WITH TWIGS AND SMALL BRANCHES

Horned Oak Gall Wasp (Callirhytis cornigera)1 hosts Pin oak primarily. Black, blackjack, and water oaks are other hosts. Damage Horned oak gall wasps produce large gnarled growths, up to the size of a golf ball, on the twigs of host trees. These ultimately develop small hornlike projections that further add to the unusual appearance of these growths. These galls can cause premature leaf drop and dieback of branches. Distribution Eastern North America in association with the native range of pin oak. Appearance The very conspicuous twig galls are commonly noticed, but the insects are rarely observed. Adults are typical gall wasps: dark colored, heavy-bodied, nonstinging wasps with a rounded abdomen. Adults that emerge from the twig galls are considerably larger than those that develop in leaf veins. Larvae are found within the galls. Life History and Habits The life cycle involves two generations. The most noticeable, comprising just females (agamic generation), is the generation that produces twig galls. The second generation produces leaf galls in the form of swelling about the midrib, and both males and females develop in this sexual generation. The initiation of the twig gall begins sometime in June, when a female lays eggs in one- or two-year-old shoots, inserting a series of eggs into the stem in a spiral pattern. There is no external evidence of the insects for the remainder of this first season. About 10 months later, in early spring, slight swellings begin to develop around the sites where eggs were laid, which contain the developing gall wasp larvae. The galls reach maximum size about two years after eggs are laid, and horned projections begin to emerge from the galls about 22 months after egg laying. Ultimate size of the gall varies and is related to the number of larvae present; up to 160 horned oak gall wasps may develop in a single gall. Early in the third spring, prior to bud break, the adult insects chew their way out of the twig galls. Females then lay eggs in the green leaf buds. Small galls in the form of swollen leaf veins are produced by the developing larvae of this generation. Adults, both male and female, emerge from these vein galls, mate, and then females lay eggs in the twigs to repeat the cycle. The old twig galls dry down and harden after the insects have emerged.

Related Species Several other Callirhytis species are also associated with oak twigs. Gouty oak gall (C. quercuspunctata) is common on scarlet, pin, shingle, and black oaks in the northeast quadrant of the U.S. and southern Canada. It produces irregular swelling of the twigs, and galls commonly occur in groups, causing girdling. Gouty oak gall has an alternate form that makes small blisterlike galls on leaves. Ribbed bud gall (C. quercusgemmaria) makes conical, strongly ribbed galls on black oak. Much smaller bulletlike galls are produced in dense clusters on twigs by ridged bunch gall wasp (C. gemmaria) on scrub, red, scarlet, and some other oaks. C. floridana is a southeastern species that makes elongate swellings on branches close to the ground on Chapman, post, and sand post oaks. The wool sower gall wasp (C. seminator) makes large, multichambered stem galls that are covered with growth of dense white hairs Other species that have stages in twigs that produce inconspicuous swellings in the twigs: Callirhytis flavipes develops in stems of bur oak, and this stage normally produces little external evidence except for exit holes produced when adults emerge in late spring. However, the larvae in twigs are often preyed on by downy woodpeckers, which may cause extensive debarking as they feed on the insects. Zapatella davisae1 develops in the twigs of black oak (Quercus velutina), producing small swellings at the feeding site. Recent outbreaks of this insect have occurred on Long Island and coastal areas of Massachusetts that have resulted in extensive twig dieback. 414

A

B

D

E C F

G H A. Horned oak galls in different stages of development. DAVID SHETLAR

B. Adults of the horned oak gall wasp. DAVID SHETLAR

C. Horned oak gall. DAVID SHETLAR

D. Individual “horn” cell exposed

within a horned oak gall.

I

LORRAINE GRANEY, BARTLETT TREE EXPERTS, BUGWOOD.ORG

E. Larva of a horned oak gall

J

wasp developing within the base of a “horn” cell. LORRAINE GRANEY, BARTLETT TREE EXPERTS, BUGWOOD.ORG

F. Gouty oak galls. DAVID SHETLAR

G. Gouty oak gall, cross section. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

K

H. Larvae of the gouty oak gall wasp. JIM BAKER, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

I. Gall produced by the wool sower gall wasp. ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

J. Exit holes made by

Callirhytis flavipes. WHITNEY CRANSHAW

K. Cells of Callirhytis flavipes exposed

by feeding of downy woodpecker. DAVID LEATHERMAN

L M

L. Galls made in the leaf midrib by

the alternate stage of Callirhytis flavipes. WHITNEY CRANSHAW

M. Crossection of black oak twig infested by Zapatella davisae. WHITNEY CRANSHAW

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

GALL WASPS ASSOCIATED WITH TWIGS AND SMALL BRANCHES

Rose Gall Wasps Almost all the galls associated with Rosa spp. are produced by gall wasps in the genus Diplolepis.1 Approximately 32 species are native to North America and a few European species have also become established. Some produce galls on leaves, but the majority are associated with stems and adventitious shoots. Some are restricted to a single host species; others may develop in three or four closely related species but make similar galls in each. Life histories of the gall wasps on rose are considerably less complex than those of most gall wasps found on oaks. All have a single generation per year and form only a single type of gall. Adults emerge by chewing their way out of the galls, with the time of emergence synchronized with the occurrence of bud or stem tissues in suitable condition; species associated with twigs usually emerge between late winter and the middle of spring. Roseroot gall wasp (D. radicum) is one of the most widespread rose gall wasps and one of the few that significantly damage plants. It produces hard, woody galls on the lower stems and upper roots that can girdle canes. The galls are multicelled, and the wasps typically emerge from them in late winter. Roseroot gall wasp is found throughout the northern U.S. and southern Canada. Diplolepis spinosa produces a large, round, multichambered stem gall covered with spines. Originally associated with native wild roses (Rosa blanda, R. woodsii), it also attacks domestic shrub rose (R. rugosa). Further stem growth can be greatly retarded by these galls. Globular galls on stems are also produced by Diplolepis fusiformis and D. tumidus. Examples of stem galls of more elongate form are produced by longrose gall wasp (D. dichlocera) and D. triforma. Mossyrose gall wasp (D. rosae) is a European species that creates twig galls covered with elaborate hairy growths, somewhat resembling sphagnum moss. The developing young are found in chambers buried in the center of the gall and survive through winter as prepupae. Pupation occurs in late winter, and the adults emerge a few weeks later to lay eggs in buds. Rosa canina, R. corymbifera, and R. rubiginosa are the primary host species.

Other Gall Wasps A small number of gall wasps develop on other plants. Diastrophus kincaidii1 uses blackberry (Rubus spp.) as a host. It produces an irregularly shaped stem gall with multiple chambers. Gall wasps are also associated with Amelanchier. Asian chestnut gall wasp (Dryocosumus kuriphilus)1 produces galls in the shoot tips, leaves, and catkins of chestnut (Castanea). Shoot growth and nut production can be severely reduced by infestations. This insect was first detected in North America in 1974 and has since spread to most of the mid-Atlantic region and west to Tennessee and Ohio. Twig and stem galls in willow are produced by Euura species.2 Adult sawflies emerge in spring, usually over a period of about 2–3 weeks. They insert eggs into developing stems, and the induced swellings develop rapidly. Larval feeding causes the gall to continue growing, and the pale yellow-green caterpillars feed for several months. Often multiple larvae occur in a single gall. Larvae of most species emerge from the gall in late summer and move to cover on the ground. Others may cut an emergence hole in late summer but remain in the gall to emerge later in spring. There is one generation per year. 1

Hymenoptera: Cynipidae; 2 Hymenoptera: Tenthredinidae

416

B

C A. Stemgall produced by Diplolepsis species of gall wasp on rose. DAVID SHETLAR

A

B. Cross section of a stemgall

produced by Diplolepsis species of gall wasp on rose exposing larvae.

D

WHITNEY CRANSHAW

C. Stemgalls produced

by Diplolepsis species of gall wasp on rose. WHITNEY CRANSHAW

D. Stemgall produced

E

by Diplolepsis species of gall wasp on rose. WHITNEY CRANSHAW

E. Mossy rose gall. DAVID SHETLAR

F. Cross section of a mossy

rose gall, exposing larvae. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G. Adult of the mossy rose gall wasp. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H. Twig galls produced by

Asian chestnut gall wasp. DAVID SHETLAR

I. Twiggalls of willow produced

F G H

I

by an Euura species of sawfly. WHITNEY CRANSHAW

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

FLIES AND CATERPILLARS THAT PRODUCE GALLS IN STEMS AND TWIGS The juniper tip midge, Oligotrophus betheli,1 develops within the emerging shoots of Rocky Mountain juniper, Utah juniper, and other Juniperus species in many midwestern and western states. The feeding injuries induce a swelling of the terminal growth that somewhat resembles a small flower. A more rounded gall of whorled leaves is produced on the tips of Utah juniper by O. juniperi. Conelike distortions of juniper buds are produced by various Walshomyia1 species. Terminal growth of many native willows may be distorted by several flies in the genus Rhabdophaga.1 Willow conegall midge (R. strobiloides) induces a conelike growth on the tips. A similar gall, more sharply drawn out, is produced by willow beakedgall midge (R. rigidae). Cypress twiggall midge (Taxodiomyia cupressiananassa)1 develops in twigs of bald cypress and pond cypress (Taxodium ascendens). Winter is spent in the fallen galls, with the developing flies pupating the following spring. Adults emerge in May and lay eggs on developing needles. Upon hatch the larvae feed at the base of the needles and induce a spongy swelling to form that usually contains a dozen or more larvae. Galls are usually somewhat pinkish during early stages but covered with whitish wax as they develop. As the insects mature the galls become more solid and turn brown. Two generations are produced each year in the more southern areas; one generation is normal in the northern parts of its range. The Canada thistle gall fly (Urophora cardui)2 is a species purposely introduced into North America to assist in biological control of Canada thistle. It produces a large, round stem gall on the plants that can have a modest negative effect on plant growth. A round, ball-shaped gall on the stems of some goldenrod is produced by Eurosta solidaginsis.2 Solidago altissima and S. gigantea are the most common hosts. A gall midge, Rhopalomyia solidaginis,1 produces a bunching of the terminal growth of S. altissima. Other galls in goldenrod are produced by caterpillars. Elliptical stem galls are produced by Gnorimoschema gallaesolidaginis3 in Solidago altissima and S. canadensis. Other Gnorimoschema species make galls in different species of goldenrod. Gall produced by Canada thistle gall fly. WHITNEY CRANSHAW

Gall of goldenrod stem produced by Eurosta solidaginsis. DAVID SHETLAR

A C

B A. Gall produced by a juniper tip midge. WHITNEY CRANSHAW

B. Willow cone galls. WHITNEY CRANSHAW

C. Gall produced by cypress twiggall midge. DAVID SHETLAR

D. Cypress twiggall cut away to expose developing midge

larvae and pupae. DAVID SHETLAR

E. Adult of the Canada thistle gall fly. WHITNEY CRANSHAW

F. Adult of Eurosta solidaginsis. TOM MURRAY

D

E

F

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

FLIES AND CATERPILLARS THAT PRODUCE GALLS IN STEMS AND TWIGS Larvae of ceanothus stem gall moth (Periploca ceanothiella)4 tunnel into stems of Ceanothus, primarily C. griseus. This produces shortening of terminal growth and induces spindle-shaped swellings on twigs. The insect is apparently widespread in association with its host but is most common in California and Oregon. Dogwood clubgall midge (Resseliella clavula)1 is common in many midwestern and eastern states. It produces tubular or club-shaped swellings at the tip or along the stem. Twigs usually die back beyond these injuries. Females lay eggs on the emerging leaves at bud break, and wilted, deformed leaves are the first indication that buds are infested. One generation is produced annually, and the insect winters in the soil. Another gall midge that distorts twig growth is linden twiggall midge (Contarinia citrina), which produces swellings just below buds of American linden. Poplar twiggall fly (Hexomyza schineri)5 commonly produces smooth swellings on the new twigs of aspen and some poplars. These galls do not normally cause noticeable effects on tree growth, but the damaged areas continue to grow long after the insects are absent, ultimately producing knobby swellings on branches and trunks. This insect has become common in the Rocky Mountain region, and reports of damage in the Midwest suggest an expanding range. Diptera: Cecidomyiidae; 2Diptera: Tephritidae; 3Lepidoptera: Gelechiidae; 4Lepidoptera: Cosmopterigidae; 5Diptera: Agromyzidae

1

420

A

B

C D A. Galls produced by ceanothus stem gall moth. ROBIN ROSETTA, OREGON STATE UNIVERSITY

B. Ceanothus stem gall moth larva exposed within stem. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Gall produced by

dogwood clubgall midge. DAVID SHETLAR

D. Linden twiggalls.

E F

G

H

JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Cross section of a linden

twiggall.

JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Poplar twiggalls on aspen. WHITNEY CRANSHAW

G. Larva of the poplar

twiggall fly within gall. WHITNEY CRANSHAW

H. Adult poplar twiggall fly. WHITNEY CRANSHAW

INSECTS ASSOCIATED WITH STEMS, T WIGS, SHOOTS, AND CANES

COOLEY SPRUCE GALL ADELGID

(Adelges cooleyi)1

hosts Colorado and Engelmann spruce, Douglas-fir Damage On spruce, distinctive cucumber-shaped galls develop on the tips of new growth, which usually kill the terminal. On Douglas-fir, Cooley spruce gall adelgids are conspicuous “woolly” aphids that suck sap from needles. When infestations occur on developing needles, symptoms may include yellowing and twisting of needles. Distribution Throughout the northern U.S. and southern Canada where spruce and Douglas-fir co-occur. Cooley spruce gall adelgid is native to North America. Appearance Exposed stages are typical “woolly” aphids, covered completely with long white waxy thread. Stages found inside galls on spruce are greenish-gray aphids covered with a fine powder of wax. Winged forms that migrate between host plants are dark green, almost black. Life History and Habits Cooley spruce gall adelgid has a life cycle involving several different forms that alternate between spruce and Douglas-fir. On spruce, winter is spent as a partially grown female on the underside of twigs. Females grow rapidly in spring, producing a large mass of several hundred eggs that hatch in synchrony with bud break. The newly hatched nymphs migrate to the base of newly expanding needles. Their feeding causes the area around the needle base to expand to form cavities, in which they develop. During late June and early July the nearly full-grown adelgids emerge through cracks in the drying galls, molt on the needles to winged adults, and migrate to Douglas-fir. On Douglas-fir, the nymphs overwinter as partially developed nymphs on the needles. They continue to develop in spring, producing a large egg mass around early May. At egg hatch the nymphs move to tips of twigs to feed primarily on the current-season needles. They become full grown in July and produce a generation of adults that are a mixture of winged and wingless forms. The wingless forms remain on Douglas-fir and have a second generation. The winged forms fly to spruce and start the cycle on this host.

Other Gall-making Adelgids Eastern spruce gall adelgid (Adelges abietis) produces a pineapple-shaped gall on Norway spruce. A European species, it is widespread in eastern Canada and the northeastern U.S. Galls are not as large as those produced by Cooley spruce gall adelgid, and affected terminals are often not killed. Also, there is no alternation of hosts, and all stages occur on spruce, with winter spent as a partially grown female located near buds. Although Norway spruce is the primary host, galls on red, white, and Colorado blue spruce are sometimes reported. Other galls on spruce may be produced by adelgids in the genus Pineus.1 Pine leaf adelgid (Pineus pinifoliae) produces a terminal distortion of spruce shoots that somewhat resembles that of Cooley spruce gall adelgid but of looser form. Galls remain green late in the season and are less conspicuous. Spruce is the primary (overwintering) host of this aphid, which infests pine during alternate stages of its life cycle.  Hemiptera: Adelgidae

1

422

A

B

C D F

G

E A. Old Cooley spruce galls on blue spruce. WHITNEY CRANSHAW

B. Mature females of Cooley spruce

gall adelgid prior to bud break. WHITNEY CRANSHAW

C. Cooley spruce gall adelgids

developing with gall. WHITNEY CRANSHAW

D. Winged forms of Cooley spruce

gall adelgid leaving galls on blue spruce. WHITNEY CRANSHAW

E. Eastern spruce gall on Norway spruce. DAVID SHETLAR

F. Cut away of eastern spruce gall

showing eggs and developing nymphs. DAVID SHETLAR

H

G. Alternate stage of the Cooley spruce

gall adelgid on Douglas-fir needles. WHITNEY CRANSHAW

H. Overwintering stage of eastern

spruce gall adelgid. DAVID SHETLAR

I. Old eastern spruce galls. LORRAINE GRANEY, BARTLETT TREE EXPERTS, BUGWOOD.ORG

J. Gall on spruce produced by pine leaf adelgid. WHITNEY CRANSHAW

I

J

CHAPTER FIVE

INSECTS ASSOCIATED WITH LARGE BRANCHES AND THE TRUNK OF TREES AND SHRUBS CLEARWING BORERS Clearwing borers (Sesiidae family) are moderate-sized, day-flying moths that have larvae that develop as borers, primarily in trees and shrubs. Appearance of the adults often mimics wasps or bees, and large areas of the forewings may lack scales, hence the name “clearwing.” Larvae are usually pale cream-colored and found in the tunnels they gouge in trunks and stems. The presence along the abdomen of 5 pairs of small prolegs, each ending in a semicircular pattern of small hooks, can differentiate clearwing borers from borer larvae that are beetles (e.g., roundheaded borers, flatheaded borers). Several clearwing borers develop below ground, feeding within the crown area or larger roots. Often referred to as “crown borers,” these species are discussed in chapter 6, on insects associated with roots. Others develop in canes or small diameter branches.

Ash/Lilac Borer (Podosesia syringae)1 hosts Most ash species, particularly green and white ash, and common lilac. Privet is another reported host. Lilac/ash borer is another common name variant for this species. Damage Larvae create rough gouging wounds under the bark and may riddle wood to a depth of about 2 inches. Injuries are concentrated in the lower 12 feet of the trunk and larger branches. Gnarled swellings form at areas of repeated attack, and sucker growth often increases. On smaller diameter branches common on lilac and privet, larval injuries may girdle and kill main stems. On lilac, older stems are preferred over young stems. Distribution Native to North America, ash/lilac borer has extended its range to include most areas where ash and common lilac are grown. Appearance Adults are brown and black moths that superficially resemble paper wasps in both size and color. The larvae are creamy white grubs with a small dark head. Prolegs on the abdomen are highly reduced, but small hooklike crochets are present at the tip of the prolegs, which allows separation from the roundheaded borers also associated with ash (page 444). Life History and Habits Ash/lilac borer spends the winter as a partially grown larva in tunnels under the bark. It resumes feeding and larval development in early spring, pupating just under a thin cover of bark. Adult emergence may begin by early April during warm springs but is usually later and may extend for several weeks with cool, overcast weather. Warm temperatures (above 60° F) and sunny conditions appear critical for adult emergence, which takes place in morning hours. Frequently the old pupal skin is only partially extruded from the emergence hole and remains attached to the tree until it weathers away. Adults are active for about 4–6 weeks after initial emergence, and females subsequently lay eggs on bark, typically near wounds or bark cracks. Eggs hatch in about 1½ weeks. Larvae tunnel into the cambium and phloem and may move an inch or more into the trunk, making irregular vertical galleries.  Lepidoptera: Sesiidae

1

424

A

B

C D

F

A. Frass expelled from trunk by larva of the banded ash clearwing. DAVID SHETLAR

B. Adult of the banded ash clearwing. DAVID SHETLAR

C. Ash/lilac borer larva exposed

from under bark.

DAVID CAPPAERT, BUGWOOD.ORG

D. Ash/lilac borer larva in twig. DAVID SHETLAR

E. Damage produced at base of

trunk by Ash/lilac borer. WHITNEY CRANSHAW

F. Mating pair of Ash/lilac borers. WHITNEY CRANSHAW

G. Pupal case of Ash/lilac borer

following adult emergence from trunk. WHITNEY CRANSHAW

H. Ash/lilac borer male

responding to pheromone lure. WHITNEY CRANSHAW

G H

E

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

CLEARWING BORERS

Other Clearwing Borers Associated with Trunks and Branches Banded ash clearwing (Podosesia aureocincta) is a closely related species found in scattered areas of the eastern U.S. It is physically very similar in appearance to ash/lilac borer, differing in having two distinct bands on the abdomen. Banded ash clearwing produces similar feeding injuries but has a different life history, with adults emerging in late summer. The lesser peachtree borer (Synanthedon pictipes)1 is associated with Prunus spp. and can be a serious pest of stone fruit trees. It is more common on older trees and will occur as a borer in areas of the tree that are aboveground, including some of the larger scaffold limbs. (This is in contrast to peachtree borer (S. exitiosa), which concentrates injuries at the base of the trunk and roots; it is discussed in more detail in chapter 6.) Lesser peachtree borer is present east of the Rocky Mountains. The dogwood borer (S. scitula)1 is a common species east of the Great Plains but is recorded from the Pacific Northwest and Colorado. It develops under the bark of a wide range of woody trees, including dogwood, pecan, oak, plum, and apple. It is particularly damaging to maple, beech, and grafted apple, where it usually attacks the burr knot tissue that forms at the graft union. Burr knots of apple, hawthorn, and pear are also the site of injury by larvae of the apple bark borer (S. pyri). On maples the maple callus borer (S. acerni) repeatedly attacks wound sites, producing an Larva of the area of progressively enlarging callus tissue. viburnum borer. Two Synanthedon species develop in the lower trunks of various species WHITNEY CRANSHAW of Viburnum, including cranberry-bush. The viburnum borer (S.  viburni) is known primarily from the Midwest; the lesser viburnum borer (S. latifera) is broadly distributed across the eastern U.S. as well as Alberta. Rhododenron and, less commonly, mountain laurel host the rhododendron borer (S. rhododendri). Conifers are hosts of other species. In the Pacific States and British Columbia the sequoia pitch moth (S. sequoiae) produces conspicuous pitch masses at its wound sites on the trunks of pines, particularly Monterey pine. In the eastern states similar injury to white, Scotch, and mugho pines as well as to spruce is produced by S. pini, known as the “pitch mass borer.” Pitch mass borer infestations are often mistaken for pitch flows associated with cytospora cankers produced by fungi Mating pair of sequoia but can be distinguished by the presence of bits of brown sawdust mixed with pitch moths. KEN GRAY COLLECTION, the pitch. Pitch mass borer larvae take 2–3 years to complete development. OREGON STATE UNIVERSITY Adults of clearwing borers in the genus Paranthrene are more heavy-bodied and typically resemble large yellowjacket wasps. Larvae of the western poplar clearwing (P. robiniae) tunnel into the base of the trunk of poplars and willows and birch, producing conspicuous swellings in smaller trees. It is broadly distributed in the western states. In the southern states east of the Rockies, similar injury to poplars and willows is produced by the cottonwood clearwing borer (P. dollii). Oaks host three other species: P. simulans (red oak clearwing borer), P. asilipennis (oak clearwing borer), and P. pellucida (pin oak clearwing borer). 1

 Lepidoptera: Sesiidae

426

A

B

C

D

E

A. Adult of the lesser peachtree borer. DAVID SHETLAR

B. Pair of dogwood borers. DAVID SHETLAR

C. Adult of the maple callus borer. DAVID SHETLAR

D. Damage by rhododendron borer

and pupa.

DAVID SHETLAR

E. Adult and pupal skins of the

rhododendron borer. DAVID SHETLAR

F. Mating pair of rhododendron

borers.

DAVID SHETLAR

G. Larva of the western poplar

clearwing.

F

G

JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

H. Adult of the western poplar clearwing. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

I. Oozing at wound site produced by oak clearwing. DAVID SHETLAR

J. Adult of an oak clearwing moth. DAVID SHETLAR

I H

J

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

CARPENTERWORM

(Prionoxystus robiniae)1

hosts A wide host range of hardwoods, with oak, elm, ash, and poplar most consistently damaged. Damage Larvae excavate large cavelike galleries in the sapwood and heartwood of trunks and large branches. Heavily infested trees may break in high winds, and chronically infested trees appear gnarled and misshapen. Larval feeding at the base of large trees allows entry of wood-rotting fungi and carpenter ants. Unlike most other wood borers, the larvae maintain an exterior opening through which they continually expel sawdust-like frass. Large exit holes and flaking of bark occur along damaged areas of trees. Distribution Generally throughout the U.S. and southern Canada. Appearance The larvae are pinkish-white caterpillars with a dark head and dark brown tubercles on the body. They are large, up to 3 inches long at maturity. Adults are large, heavy-bodied moths, somewhat resembling sphinx moths (page 68). They have grayish forewings, mottled with black. Life History and Habits Carpenterworms winter as larvae in the tunnels produced in infested trees. Pupation occurs in spring, and adult moths appear around May. Often the purplish pupal case remains extruded from the exit hole until it has weathered away. Eggs are laid in clusters top: Carpenterworm larva. WHITNEY CRANSHAW in bark crevices or near wounds. After egg hatch the larvae bore directly above: Pupal case of a carpenterworm. into the phloem and cambium just under the bark. Early signs are small DAVID SHETLAR damp spots on the bark. They later extend tunnels into the sapwood and ultimately the heartwood. Typically they form a central cavity with side tunnels that may extend for several inches. Sawdust is regularly ejected and may conspicuously collect around the base of infested trees. Carpenterworm has a fairly long life cycle, ranging from 1 to 2 years in southern areas and 3 to 4 years in the north.

Other Carpenterworms Leopard moth (Zeuzera pyrina),1 an apparent introduction from Europe now found in the northeastern states, nearly rivals carpenterworm in size. Young larvae tunnel twigs and small branches but leave when they get too large. External evidence of tunneling is obvious, with wood chips and excrement being pushed to the outside as the larvae feed. A wide range of hardwood trees are hosts. Development requires 2 years to complete. Eggs may be laid from late spring through September. Pecan carpenterworm (Cossula magnifica)1 occurs in the southern states and appears to complete its life cycle in a single year. Pecan, oak, and hickory are hosts. As the caterpillars feed, they continually push sawdust from feeding sites. Eggs are laid in May and June. Affecting Populus species are two species, poplar carpenterworm (Acossus centerensis),1 primarily eastern, and aspen carpenterworm (A. populi), more broadly distributed throughout North America.  Lepidoptera: Cossidae

1

428

A. Adult carpenterworm. DAVID LEATHERMAN

B. Carpenterworm larva in tunnel. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

C. Pecan carpenterworm in branch. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

D. Tunnels produced by pecan carpenterworm. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

E. Adult of the pecan carpenterworm. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

F. Adult of Acossus populi, a

carpenterworm associated with Populus.

B

JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

C

A D

E

F

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

ZIMMERMAN PINE MOTH

(Dioryctria zimmermani)1

hosts Pine, particularly Scotch and Austrian pines. Damage Larvae tunnel under the bark, typically at crotches of branches. Branches may break or die directly from effects of the girdling. Infestations are commonly marked by dead and dying branches, often in the upper half of the tree. External symptoms of injury are popcorn-like pitch masses at the wound site. Distribution Most common in midwestern and Great Lakes States but is present from eastern Colorado to New England, with additional populations now established in many areas of the Pacific States. Appearance The adults, rarely observed, are midsized moths with gray wings blended with red-brown and marked with zigzag lines. Larvae are generally dirty-white caterpillars, occasionally with some pink or green coloration. They are found under the characteristic popcorn-like masses of sap on trunks and branches. Life History and Habits The insect overwinters as a very young caterpillar inside a small cocoon (hibernaculum) underneath scales of bark. In mid- to late April and May it again becomes active and tunnels into the tree. Tunneling typically occurs at preexisting wounds or at the junction of the trunk and branch. The larvae feed into July and early August, at which time large amounts of pitch are produced. Prior to pupation they gouge out large areas under the bark, leaving a thin bark flap, and pupate just underneath this. Adult moths are active primarily in late July and August. After mating, female moths lay eggs, often near wounds or previous masses of pitch. Eggs hatch in about a week and the larvae move immediately, without feeding, to protected sites on the bark, where they overwinter in the hibernaculum.

Other Pyralid Borers Dioryctria ponderosae,1 sometimes known as “pinyon pitch mass borer,” is found in the High Plains and Rocky Mountain regions of the U.S. Pinyon growing in overirrigated sites is most commonly damaged; ponderosa pine is also affected. Irregular wounds under the bark are produced, where a creamy or slightly pinkish ooze mixes with pieces of sawdust and frass. Dioryctria cambiicola is another western species associated with branch tunneling of ponderosa pine. Southern pine coneworm (D. amatella) is primarily a cone-feeding species but will occasionally damage large branches and even trunks, concentrating at points of previous wounding or fungal infections. Retinia comstockiana (pitch twig moth)2 is an eastern species that produces pitch masses in limbs and occasionally trunks of soft pines. American plum borer (Euzophera semifuneralis)1 is a minor pest of fruit trees, occasionally damaging various nut and shade trees. It is associated mostly with stressed trees or existing wounds, including poor pruning cuts. It is found primarily throughout the eastern U.S., but is known as far west as Arizona. Most tunneling occurs in the lower 4 feet of the trunk and almost always originates near previous wounds. The larvae are grayish green to grayish purple and pupate in a silken cocoon, often under bark flaps. prickly pear cactus moth (Cactoblastis cactorum)1 is an introduced species, native to South America, that develops in pads of various prickly pear cacti (Opuntia spp.). Full-grown larvae may exceed 1 inch and are orange-red with dark bands of dots. In addition to feeding injuries produced by the insects, decay organisms invade damaged plants, and collectively these injuries can extensively damage and often kill plants. From areas in Florida where this insect was originally discovered, it has since spread as far as Louisiana and South Carolina.  Lepidoptera: Pyralidae; 2 Lepidoptera: Tortricidae

1

430

A. Dorsal, side and ventral views of Zimmerman pine moth larvae. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Pitch mass produced by

Zimmerman pine moth. DAVID SHETLAR

C. Larva of Zimmerman pine

moth exposed from pitch mass. JIM KALISCH, UNIVERSITY OF NEBRASKA

A

D. Adult Zimmerman pine moth.

B

DAVID SHETLAR

E. Young larva of a Zimmerman pine

C D

moth in overwintering hibernaculum. DAVID SHETLAR

F. Pinyon pitch mass borer

exposed from pitch mass. WHITNEY CRANSHAW

G. Oozing from wounds produced

by pinyon pitch mass borer. WHITNEY CRANSHAW

H. Pitch mass produced by

pitch twig moth. DAVID SHETLAR

I. Larva of the American plum borer.

E

F

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

J. Larva of the prickly pear

cactus moth.

SUSAN ELLIS, USDA APHIS PPQ, BUGWOOD.ORG

K. Damage produced by prickly

pear cactus moth.

SUSAN ELLIS, USDA APHIS PPQ, BUGWOOD.ORG

G H

I K

J

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

METALLIC WOOD BORERS/FLATHEADED BORERS The metallic wood borers (Buprestidae family) are elongate, slightly flattened beetles with a metallic sheen. Larvae are known as flatheaded borers because the first segment of the thorax (prothorax) is often greatly widened and flattened. Legs are absent and the larvae chew tunnels under bark or in wood. Characteristic tunnels produced by most species are zigzag and filled with tightly packed, fine sawdust excrement. Most of the nearly 700 North American species limit attacks to areas of trees and shrubs that have been injured or attacked by fungal cankers or that are in advanced decline or even recently dead. However, a considerable range exists among flatheaded borers in the degree of attack on trees, with some species capable of killing trees in fair to good health.

Bronze Birch Borer (Agrilus anxius)1 hosts Birch; European white birch and Jacquemonti birch are particularly susceptible. Damage Larvae develop by tunneling the cambium layer, under the bark. Girdling injuries first cause limb dieback, with thinning of the crown an early symptom of infestation. Trees are frequently killed following sustained infestation. Birch grown in suboptimal sites, especially where periodic drought stress may occur, are most commonly infested. Distribution Throughout the range of birch in southern Canada and the northern half of the U.S. Most recently the range has extended to the Pacific Northwest. Appearance The adults are elongate, somewhat flattened beetles from ⅜ to ½ inch long. Overall coloration is olive black with coppery reflections. The elongate larvae are creamy white with the first thoracic segment enlarged and flattened in a manner typical of flathead borers. Life History and Habits Adults emerge in late May or early June, cutting a D-shaped opening through the bark. They feed on leaves for 1–2 weeks before eggs mature. Females lay eggs in bark crevices, around curls of bark, and in other protected sites, primarily on the unshaded sides of trunks and branches. During the initial phases of attack, most egg-laying is concentrated in the upper crown on branches less than 1 inch in diameter. Larger branches and ultimately the trunk are attacked as infestations progress. Eggs hatch in about 2 weeks, and the larvae tunnel into the cambium where they spend most of their lives, rarely moving into the xylem. Larval galleries often have a zigzag pattern and are packed with fine sawdust frass. Trees that overgrow these wounds with callous tissue may show evidence of tunneling as raised lumps or ridges, externally visible on bark. Mature larvae overwinter and pupate early in the spring. There is usually one generation per year; 2 years may be required in northern areas to complete the life cycle.  Coleoptera: Buprestidae

1

432

A

B

C A. Bronze birch borer laying eggs in bark crack. DAVID SHETLAR

B. Larva of the bronze

birch borer.

WHITNEY CRANSHAW

C. Raised areas of bark

indicating wound response by tree to bronze birch borer damage. DAVID SHETLAR

D. Tracks under bark made by developing larvae of bronze birch borer. WHITNEY CRANSHAW

D

E. D-shaped exit hole

(lower) produced by bronze birch borer. The circular hole above was produced by a parasitic wasp that attacks bronze birch borer.

E

WHITNEY CRANSHAW

F. Birch tree in decline

from bronze birch borer injuries.

F

WHITNEY CRANSHAW

433

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

METALLIC WOOD BORERS/FLATHEADED BORERS

Emerald Ash Borer (Agrilus planipennis)1 hosts Ash (Fraxinus). On rare occasion it has been observed to attack white fringetree (Chioanthus). Damage The larvae of emerald ash borer develop under the bark of trees, creating zigzag tunnels through the cambium. Cumulative injuries cause a progressive dieback that initially involves upper limbs but ultimately moves into the trunks. Typically trees are killed within 5 years after they are first colonized. Distribution The first North American detection of emerald ash borer was in 2002 in Detroit. By 2016 this insect was found in most states east of the Mississippi, two Canadian provinces, and two western states (Colorado, Texas). The rapid spread of this insect over wide areas has been largely through the human-assisted movement of infested ash firewood. Once introduced into a location, local dispersal occurs from the flight of adults during late spring and early summer. Appearance Adults are metallic green beetles, approximately ½ inch long. The larvae are flatheaded borers that make meandering tunnels through the cambium, under the bark. Adults emerge from trees through D-shaped exit holes in the bark. Life History and Habits Winter is spent as a larva within tunnels under the bark and pupation occurs in mid-spring. Adults can be expected to begin to emerge in late May, about the time black locust (Robinia) is in full bloom. Initially they feed on the foliage and, about 2 weeks later, after mating, females begin to lay eggs on the surface of trunks and branches. About 100 eggs may be laid on the trunk or larger limbs, usually at points of rough bark and in cracks of the bark, with most egg laying completed by early July. Eggs hatch about 2 weeks after being laid, and the larvae bore into the plant where they feed on the sapwood. As they feed and develop the larvae extend their mines under the bark, the size of the tunnels gradually widening as the insect grows. Fine sawdust frass packs these galleries. Larval feeding continues until the larva is mature or until weather becomes too cold for development. Growth is resumed in spring when they complete their development. Normally, one generation is produced annually. Development may be slowed in more vigorous trees in early stages of infestation and in cooler areas some larvae that develop from eggs laid late in the season have been observed to require a second season to mature.

A. Emerald ash borer mating pair. DAVID CAPPAERT, BUGWOOD.ORG

B. Emerald ash borer

resting on leaf. DAVID SHETLAR

C. Emerald ash borer

with wings opened. DAVID SHETLAR

D. Extensive larval tunneling

by emerald ash borer.

ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

E. Emerald ash borer larva. DAVID CAPPAERT, BUGWOOD.ORG

F. Emerald ash borer adult next to exit hole. DAVID SHETLAR

434

B C

A D

E

F

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

METALLIC WOOD BORERS/FLATHEADED BORERS

Related Species Approximately 25 species of Agrilus1 occur in North America. Adults are fairly small (⅓–⅝ inch) elongate beetles and a metallic bronze, green, or blue color. Larvae damage plants by making zigzag or spiraling tunnels under the bark. The life cycle is completed in a single year under normal conditions, with the nearly full-grown larva as the overwintering stage. Several limit injuries to canes or small diameter branches; these are discussed on page 348. Twolined chestnut borer (Agrilus bilineatus), which develops in oak and chestnut, is particularly damaging to trees previously stressed by defoliation by gypsy moth or other causes. It is widely distributed over much of the eastern half of North America, south to Georgia. Adults emerge from trees in early June and intersperse feeding on leaves of the host and other hardwoods with egg-laying and mating. Adults are bluish black with a pale, rather indistinct stripe running the length of each wing cover. Closely related A. carapini attacks hornbeam, especially European hornbeams. Gambel oak borer (A. quercicola) occasionally moves in outbreak numbers from native stands of Gambel oak into landscape plantings of other oak species in parts of the southern Rocky Mountain region. Goldspotted oak borer (Agrilus coaxalis) has recently emerged as a seriously damaging borer affecting coast live oak and California black oak. This insect is thought to be native to areas of southeastern Arizona and northern Mexico, where it was formerly a minor species of secondary pest importance. First detected in southern California in 2004, it has proved to be much more damaging to oaks in this area of recent range expansion, with effects compounded by chronic drought. Another native of Mexico that has expanded its range into Texas is the soapberry borer (A. prionurus), which has caused heavy losses to western soapberry greater than 2 inches diameter. Honeylocust borer (Agrilus difficilis) has become increasingly important with the extensive planting of its host, honeylocust, as a common street tree. Tunneling is usually restricted to larger branches and the trunk and almost always concentrated in areas of the tree affected by fungal cankers or wounds. It can girdle and kill recently transplanted trees. Honeylocust borer is known from New Jersey to Michigan, south to Georgia, and west to Texas and Colorado. Adults are metallic black with greenish or purplish tints. Adult beetles emerge over an extended time and have been observed from May through September. Several other Agrilus can be common in shade trees that are in decline or damaged by wounds or fungal pathogens. Poplar, cottonwood, and aspen are hosts for bronze poplar borer (Agrilus granulatus liragus), granulate poplar borer (A. g. granulatus), and western poplar agrilus (A. g. populi), found in northern, southern, and western North America, respectively. Common willow agrilus (A. politus) is found in branches of maple and willow throughout North America. Sinuate peartree borer (A. sinuatus) is a European species now established in parts of the Mid-Atlantic States, where it damages pear.  Coleoptera: Buprestidae

1

436

A

B

C D

E

F

A. Twolined chestnut borer. DAVID SHETLAR

B. Larva of a twolined chestnut borer. DAVID SHETLAR

C. Gambel oak borer emerging from tree trunk. WHITNEY CRANSHAW

D. Goldspotted oak borer. MIKE LEWIS, CENTER FOR INVASIVE SPECIES RESEARCH, BUGWOOD.ORG

E. Honeylocust borer. WHITNEY CRANSHAW

F. Larval tunneling produced by bronze poplar borer. DAVID LEATHERMAN

G. Exit holes produced by honeylocust borer. WHITNEY CRANSHAW

G

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

METALLIC WOOD BORERS/FLATHEADED BORERS

Flatheaded Appletree Borer (Chrysobothris femorata)1 hosts A wide range of food plants, including most deciduous fruit, forest, and shade trees and shrubs. Maple and apple are among the common hosts. Damage Larvae tunnel under the bark of trunks and larger branches, producing broad galleries tightly packed with fine sawdust frass. Areas of bark where injury has occurred often appear darkened, somewhat sunken, and may later split above the injury. On young trees, tunneling may girdle and kill the plant; tunnels are more restricted in area on established trees. Injuries are concentrated on the sunny side and most common on trees suffering sunscald, wounds, or drought stress. Areas of a graft union are particularly favored sites. Distribution Throughout the U.S. and southern Canada but common in the eastern and central states. Appearance Adult wood borers are dark metallic olive gray to brown, about ½ inch long. Larvae are pale yellow, legless, with an enlarged prothorax. Life History and Habits Winter is spent as larvae under the bark. They complete development the following spring, cut a chamber into the sapwood, and pupate. Adults may begin emerging by mid-spring, but peak activity is from late May through June. The females may be observed searching the sun-exposed sides of trunks of host trees. Eggs are laid singly in bark cracks or near existing injuries, and over the course of a month about 100 eggs may be laid. Eggs hatch within 8–16 days, and the larvae chew through the bottom of the egg and begin to tunnel into the tree. Larval development can be rapid and gallery formation extensive in low-vigor trees. Development is retarded (and tunneling more restricted) in trees of high vigor. The larvae continue to feed for several months, becoming dormant during the cold season. There is one generation per year.

Related Species The flatheaded appletree borer is part of a group of about 12 species in the “Chrysobothris femorata species complex”; these are very difficult to distinguish using external features, but they have differences in host range. A great many of the host records attributed to the flatheaded appletree borer could involve one or more of these other species. Pacific flatheaded borer (Chrysobothris mali) predominates west of the Rockies, flatheaded appletree borer to the east. Biology of the two species are similar. Pacific flatheaded borer is damaging mostly to newly planted trees and shrubs and those damaged by sunscald.  Coleoptera: Buprestidae

1

438

A

B

C D

E F A. Flatheaded appletree borer laying eggs on oak. DAVID SHETLAR

B. Larva of the flatheaded

appletree borer. DAVID SHETLAR

C. Damage to sycamore

produced by flatheaded appletree borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

G H

D. Tunneling of ash limb produced by flatheaded appletree borer. WHITNEY CRANSHAW

E. Larvae of Pacific

flatheaded borer.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Exit holes produced by flatheaded appletree borer. WHITNEY CRANSHAW

G. Pupa of Pacific

flatheaded borer.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

I

H. Damage to the lower trunk caused by larval tunneling of Pacific flatheaded borer. ROBIN ROSETTA, OREGON STATE UNIVERSITY

I. Adult Pacific flatheaded borer. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

LONGHORNED BEETLES/ROUNDHEADED BORERS The longhorned beetle family (Cerambycidae) includes some of the most visually striking beetles. Most are fairly large, and the most massive of all North American insects are found in this group. Color can be variable, with some species dully colored brown or gray and others brightly colored. Very long antennae, sometimes exceeding the body length, are characteristic of most species. Larvae, known as roundheaded borers, produce tunnels that are oval to round in cross section, with tunneling by some species concentrated in the sapwood, while others prefer the heartwood. Legs of roundheaded borers are highly reduced, and the body is relatively uniformly cylindrical, although slightly constricted at most segments. (Roundheaded borers are often similar in body form to clearwing moth larvae, but the moth larvae can be distinguished by short prolegs on the abdomen tipped with small hooks.) More than 900 species are known from North America, but very few seriously damage living trees. Most are associated only with nearly dead or recently killed trees and shrubs. A few of the roundheaded borers develop in the crown area at the base of the plant and in larger roots; these species are discussed in chapter 6. A few smaller species restrict feeding to small-diameter branches or canes and are discussed in chapter 4.

Locust Borer (Megacyllene robiniae)1 hosts Black locust. Damage Larvae develop in trunks, causing deep tunneling that can riddle the plant and cause serious structural weakening. Distribution Expanding. Its range currently includes much of North America, excluding some Pacific States and southern Florida. Locust borer is common in black locust stands. Appearance The adult is a colorful, generally black beetle marked with yellow cross bands on the thorax and W-shaped bands on the wing covers. It is about ¾ inch in length with antennae nearly as long as the body. The larvae, about 1 inch long when fully grown, are robust, cream-colored, legless grubs with a brown head. Life History and Habits Adults are active in late summer and early fall, considerably later than most longhorned beetles. At this time they are commonly seen feeding on the pollen of goldenrod and other yellow flowers. Concurrently, eggs are deposited in cracks and crevices in the bark of host trees. Larvae hatch in late fall, bore into bark, and construct small hibernation cells for overwintering. They resume activity in the spring and tunnel extensively through heartwood. The larvae mature in the latter part of July. There is one generation per year.

Related Species Some very attractive Megacyllene species commonly develop in recently killed trees. Painted hickory borer (M. caryae) occurs throughout the eastern U.S. and is associated with various nut trees, black locust, locust, mulberry, and ash. This beetle often emerges from firewood during winter and spring months, when it is often mistaken for the locust borer. Acacia and mesquite host mesquite borer (M. antennatus) in the southwestern states. Although adults may be observed visiting flowers and emerging from firewood or recently cut lumber, they are not damaging to healthy trees.

440

A. Internal tunneling produced by locust borer larvae. WHITNEY CRANSHAW

B. External evidence of locust

borer damage.

WHITNEY CRANSHAW

C. Locust borer. DAVID LEATHERMAN

D. Locust borer adults on

goldenrod.

WHITNEY CRANSHAW

A

B C D

E

E. Painted hickory borer. DAVID SHETLAR

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

LONGHORNED BEETLES/ROUNDHEADED BORERS

Poplar Borer (Saperda calcarata)1 hosts Primarily aspen, but cottonwood and poplar are also hosts Damage Larvae develop under the bark and tunnel the sapwood, girdling trees. Early stages of attack are indicated by moist areas on the bark, often with some associated sawdust. Chronically infested trees exhibit a black varnishlike stain on the bark below points of borer attack. Stringy sawdust is pushed out of holes in the bark by the developing larvae and may pile around the base of trees. Branches and trunks may break off in high winds and trees may be invaded by wood rot. Wound sites also develop as rough growths that may split the bark. Attacks are generally restricted to large-diameter, overmature trees. Trees most affected are in direct sunlight and generally suffering from some growing stresses (e.g., drought) related to the site. Distribution Poplar borer is a very widely distributed species in most of North America. Appearance Adults are generally gray beetles, about 1¼ inches long, with a central yellow stripe on the thorax and some black and yellow stippling marks on the wing covers. Poplar borer adult. Larvae are large, yellowish, round-headed grubs, about 1⅜ JIM KALISCH, UNIVERSITY OF NEBRASKA inches long when mature and found only within their tunnels. Life History and Habits Adults emerge from trees beginning in May and June in southern areas; June and July in northern sites. After emerging from the tree they first feed on the leaves and young shoots of their host for about 2 weeks. The females then begin to lay eggs, which they deposit in niches they chew into the bark of the trunk. Larvae first feed in the bark and later bore into the sapwood, where they tunnel upward, producing a gallery that may extend about 1 foot in length. Unlike most borers, throughout their period of feeding they maintain an opening to the outside, through which they push the boring dust. Pupation occurs in spring, within a chamber cut just beneath the bark. The poplar borer has an extended life cycle that normally takes two years to complete in southern areas and may be considerably longer in cooler climates.

Related Species Poplar-gall saperda (Saperda inornata) induces swellings on the twigs of aspen, poplar, and willow. Elm borer (S. tridentata) develops in dead or weakened American elm, sometimes causing dieback of individual limbs. Linden borer (S. vestia) is sometimes an important pest of linden, particularly little-leaf linden, in the Midwest. Alder borer (S. obliqua) develops in alder and birch in the northern U.S. and Canada. Larvae of the roundheaded appletree borer (Saperda candida) develop in trees and shrubs of the rose family, including apple, pear, quince, cotoneaster, hawthorn, mountain-ash, serviceberry, and crabapple. Larvae tunnel the trunks at the base of trees and they are particularly destructive to young apple trees. Adults are present from late April through June, depending on location, and the life cycle often extends for 2 years. Roundheaded appletree borer occurs east of the Mississippi River, north of the hill areas of Georgia to Alabama. 442

A. Life stages and injury of poplar borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

B. Poplar borer larvae. WHITNEY CRANSHAW

B

C. Sawdust and ooze produced

wound site of poplar borer larval injury.

C

WHITNEY CRANSHAW

D. Linden borer. PENNSYLVANIA DEPARTMENT OF CONSERVATION AND NATURAL RESOURCES–FORESTRY, BUGWOOD.ORG

E. Elm borer. DAVID SHETLAR

F. Roundheaded appletree borer. DAWN DAILEY O’BRIEN, CORNELL UNIVERSITY, BUGWOOD.ORG

G. Larva of roundheaded appletree

borer.

JIM KALISCH, UNIVERSITY OF NEBRASKA

A E

H. Injury produced by poplar gall

D

saperda.

USDA FOREST SERVICE–NORTH CENTRAL RESEARCH STATION, BUGWOOD.ORG

I. Pupa of elm borer. DAVID SHETLAR

F

G H

I

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

LONGHORNED BEETLES/ROUNDHEADED BORERS

Other Longhorned Beetles Commonly Found in Trees and Shrubs Redheaded ash borer (Neoclytus acuminatus)1 develops in ash, hackberry, several fruit trees, and other hardwoods. Most attacks occur on dying or recently killed trees, and they are common on firewood. Larval feeding can reduce the sapwood to a fine powder, and large oval-shaped holes may riddle the heartwood. Occasionally there is boring into twigs and branches. The adult beetles have a narrow brown body with a reddish head and thorax. They are about ⅝ inch long and have wing covers marked with four yellow transverse bands and long spindly legs. Redheaded ash borer is found in much of the continent east of the Rocky Mountains. Banded ash borer (N. caprea) is generally similar in appearance and habits. It is marked with yellow stripes on the wing covers and slightly larger than redheaded ash borer. Biology is similar. N. muricatulus is associated with spruce and other conifers. Eucalyptus longhorned borer (Phoracantha semipunctata)1 became established in California around 1984 and is now found attacking many eucalyptus species in the southern half of the state. Adults may lay eggs in small batches, and larvae originally feed just under the bark, often producing oozing sap that produces dark streaks down the trunk. Older larvae penetrate the cambium, and tunnels may ultimately extend several feet. A second, related species, P. recurva, has more recently become established in southern California and may prove more damaging. These longhorned beetles are capable of producing 2 or 3 generations annually. Asian longhorned beetle (Anoplophora glabripennis)1 has been the object of considerable attention and concern since it was discovered in the New York City and Chicago areas in the late 1990s. Maple and poplar are preferred hosts, but a wide variety of hardwood trees are potential hosts. The larvae tunnel extensively in the trunk and branches, resulting in dieback and structural weakening. The adult, sometimes known as “starry sky beetle,” is a large (1–1½ inches), coal-black beetle, often with steel-blue tones, bright white markings, and banded antennae. The species is native to Japan, Korea, and eastern China. Pole borer (Parandra brunnea),1 also known as aberrant wood borer, tunnels the heartwood of many hardwoods including willow, maple, elm, and poplar. It is usually associated with dead areas of wood but causes extensive riddling that can structurally weaken plants. As its name suggests, it is sometimes a problem in telephone poles and structural lumber. It is “aberrant” in appearance, lacking the long antennae characteristic of other longhorned beetles and possessing prominent jaws that make it appear somewhat like a predator. Pole borer is one of the very few wood borers capable of reproducing without emerging from the trunk. Asian longhorned beetle. DAVID SHETLAR

444

A

B

C D

G H

E

F

A. Redheaded ash borer. DAVID SHETLAR

B. Larva of redheaded

ash borer.

DAVID SHETLAR

C. Banded ash borer. DAVID CAPPAERT, BUGWOOD.ORG

D. Eucalyptus borers. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

E. Damage produced

by eucalyptus borers.

I

J

DAVID SHETLAR

F. Egg niche chewed

into bark by Asian longhorned beetle. DAVID SHETLAR

G. First-instar larva of

Asian longhorned beetle. DAVID SHETLAR

H. Larvae of Asian

longhorned beetle.

K

STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

I. External symptoms of infestation by Asian longhorned beetle. DAVID SHETLAR

J. Pole borer showing

range of size of adults. WHITNEY CRANSHAW

L

K. Riddling of trunk

by pole borer larvae. WHITNEY CRANSHAW

L. Pole borer larva. WHITNEY CRANSHAW

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

OTHER LONGHORNED BEETLES COMMONLY FOUND IN TREES AND SHRUBS Species in the genus Callidium1 develop in dead, dying, and seriously stressed conifers. Larvae sculpt tunnels just under the bark and often pack them with granulate frass. Boring activity is also commonly observed as the larvae expel sawdust from wood piles. Blackhorned pine borer (C. antennatum) commonly infests dead pines and sometimes those recently transplanted in poor sites. It is common in the Rocky Mountain region, throughout the southern states, and in most of the eastern U.S. and Canada. A closely related species is blackhorned juniper borer (C. texanum), which occurs in juniper. Adults of both species are shiny black or blue-black longhorned beetles. Pine sawyers (Monochamus spp.)1 are widespread in North America, developing in recently dead and severely stressed pine, spruce, fir, and Douglas-fir. Adults are large beetles (about 1 inch long), black to brownish gray with white speckling, and have extremely long antennae one to three times the body length. Larvae bore extensively in sapwood and heartwood of dying and recently killed trees. Adults cause minor injury by feeding on needles and shoot bark. In the Midwest, pine sawyers are the primary vectors Blackhorned pine borer. of pine wilt nematode (Bursaphelenchus xylophilus), which can STEVEN VALLEY, OREGON DEPARTMENT WOF AGRICULTURE, BUGWOOD.ORG produce pine wilt disease in susceptible pines; non-native pines (e.g., Scotch pine, Austrian pine) are most susceptible to this disease. The nematode is introduced into feeding wounds of twigs made by the adult and physically carried from tree to tree on the body of the beetles. This twig feeding may also cause flagging of damaged branches from girdling wounds. Common species include whitespotted sawyer (M. scutellatus), spotted pine sawyer (M. clamator), and southern pine sawyer (M. titillator). Larvae of cactus longhorn (Moneilema armatum)1 tunnel the pads of various cacti in the genera Opuntia and Cylindropuntia. They survive winter in a pupal cell they construct during late summer and early fall around the base of the cactus. Transformation to the pupal stage occurs in spring, and adults emerge in late spring and early summer. Adult beetles feed at night, typically eating young cactus pads or oozing sap. After mating, the females glue eggs to the cactus pad. The young larvae attempt to tunnel into the cactus, causing the plant to ooze sap at the wound. The larvae first feed in this ooze, later entering the plant. They feed throughout the summer and early fall. One generation is usually produced per year, but some of the later larvae may not emerge until the second season. Several other species of Moneilema occur in the southwestern U.S., all restricted to various cacti. M.  annulatum, M. appressum, and M. semipunctatum generally resemble cactus longhorn but are somewhat smaller. The ash and privet borer (Tylonotus bimaculatus)1 can develop in many hardwoods but is most damaging to ash and privet. Adults are present from May through August and lay eggs under bark scales. At egg hatch the larvae bore into the trunk and initially feed in the phloem tissues just under the bark, but they tunnel more deeply and extensively as they get older. Larger limbs of ash are usually attacked, but advanced infestations can move into the trunk. Injury to privet is typically concentrated at the base of the plant. Damage is most often associated with drought-stressed and over-aged plants, particularly in shelterbelt plantings. The ash and privet borer occurs over a wide area east of the Rockies but is most often observed in the states and provinces of the High Plains.  Coleoptera: Cerambycidae

1

446

A

B C D

E

F

G

H

I

A. Callidium species larva in juniper log.

J

WHITNEY CRANSHAW

B. Branch tunneling produced by larvae of blackhorned pine borer. WHITNEY CRANSHAW

C. Spotted pine sawyer. WHITNEY CRANSHAW

D. Whitespotted pine sawyer. DAVID SHETLAR

E. Southern pine sawyer. NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

F. Larva of a pine sawyer. DAVID LEATHERMAN

G. Tunneling produced

by southern pine sawyer. Smaller tunnels are produced by bark beetles. W. H. BENNETT, USDA FOREST SERVICE, BUGWOOD.ORG

H. Cactus longhorn. WHITNEY CRANSHAW

I. External evidence of

larval tunneling by cactus longhorn. WHITNEY CRANSHAW

J. Ash and privet borer. DAVID SHETLAR

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

POPLAR AND WILLOW BORER

(Cryptorhynchus lapathe)1

hosts Willow and, rarely, poplar Damage Larvae tunnel into the lower trunk of trees. Infested trees may become malformed because of excessive sucker growth. Young willows may have bulblike swellings from borer attack and may break easily because of borer weakening. Distribution An introduced species now broadly distributed throughout southern Canada and the northern U.S. Appearance Larvae are cream-colored, legless, C-shaped grubs about ¼ inch long. At points of feeding, large amounts of moist sawdust are pushed from the entry holes. The adults are chunky snout weevils, about ⅜ inch long, and rough-surfaced. They are primarily black except for the hind third of the wing covers, which are gray, somewhat resembling a bird dropping. Life History and Habits Poplar and willow borer spends the winter as a partially grown larva in the sapwood. In the spring, the larvae grow and continue boring, pushing large amounts of fibrous frass through exit holes. Larvae pupate under the bark, beginning in May. Adults may be present from late May through mid-July. Eggs are deposited in small slits in the bark. There is 1 generation per year.

Other Trunk-boring Weevils Agave weevil (Scyphophorus acupunctatus)1 can be a serious pest of agave and yucca in the southernwestern states and Florida. Adults make feeding punctures in young leaves. Most damage is produced by larval tunneling, which occurs primarily at the base of the flowering stalk, but it can also kill the growing point. Secondary infections with rotting organisms commonly follow agave weevil damage, sometimes causing plants to collapse and die. Agave weevil is a large (ca. ½–¾ inch) black snout beetle. Larvae are creamy white, legless, and may be ¾ inch when fully grown. The life cycle can be completed in less than 2 months, and up to 4 or 5 generations may be produced annually in more southern areas. A closely related species found in southern California is yucca weevil (S. yuccae). Palmetto weevil (Rhynchophorus cruentatus)1 is the largest North America weevil and present in many southern states from South Carolina to Texas. Adults may exceed 1 inch in length and have highly variable coloration, ranging from completely black to nearly all red. Adults are usually observed in late spring and early summer. The larvae develop as destructive borers of cabbage palm, occasionally damaging saw palmettos and some other palms. Infestations are often lethal as the larvae extensively tunnel the trunk and may kill the growing point. Serious rots usually develop around wounded areas. Adults usually lay eggs near existing wounds. Emergence holes made by the exiting adult may be the diameter of a quarter. Multiple generations can occur, with the life cycle taking about 3 months to complete under optimal conditions. Red palm weevil (Rhynchophorus ferrugineus) is considered the most damaging insect pest of palms worldwide. Recently it has been found established in an area of southern California. Adults chew pits in the trunk, often near the base of fronds, and the larvae develop as borers within the upper trunk. Extensive tunneling is produced by the larvae that can cause the tops of plants to be killed. Canary Island date palm is one of the more susceptible species and widely grown in the area where this insect has been found.  Coleoptera: Curculionidae

1

448

A

B

D

E

C F

A. External evidence of larval tunneling by poplar and willow borer.

G

WHITNEY CRANSHAW

B. Pupa and tunneling damage

of poplar and willow borer. WHITNEY CRANSHAW

C. Poplar and willow borer adult. DAVID LEATHERMAN

D. Agave weevil adults and larvae. STEPHEN H. BROWN, UNIVERSITY OF FLORIDA

E. Agave weevil larva. LYLE BUSS, UNIVERSITY OF FLORIDA

F. Tunneling of the base of

agave by agave weevil larvae. STEPHEN H. BROWN, UNIVERSITY OF FLORIDA

G. Adult yucca weevil. JENNIFER C. GIRON DUQUE, UNIVERSITY OF PUERTO RICO, BUGWOOD.ORG

H. Palmetto weevils. DOUG CALDWELL, UNIVERSITY OF FLORIDA

I. Palmetto weevil larvae. LYLE BUSS, UNIVERSITY OF FLORIDA

J. Adult, larva and pupa

of red palm weevil.

CHRISTINA HODDLE, UNIVERSITY OF CALIFORNIA-RIVERSIDE, BUGWOOD.ORG

K. Larvae and damage

by red palm weevil larva. CHRISTINA HODDLE, UNIVERSITY OF CALIFORNIA-RIVERSIDE, BUGWOOD.ORG

H I

J

K

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

HORNTAILS The horntails (Siricidae family) are large, thick-bodied wasps that develop as wood borers in recently killed and dying trees. Females are stingless but possess a prominent ovipositor used to insert eggs under bark. All horntails have a mutualistic association with wood-rotting fungi that are introduced during egg-laying and help provide food for the grublike young.

Pigeon Tremex (Tremex columba)1 hosts Many hardwood trees, including maple, beech, hickory, elm, oak, apple, pear, sycamore, and hackberry. Maple and beech are preferred. Damage Larvae develop as wood borers, creating meandering tunnels that can increase susceptibility to wind breakage; however, damage is confined to dead or dying wood. Adults inject wood-rotting fungi into trees which contributes to tree declines and structural weakening. Distribution Throughout the U.S. and southern Canada, west to the Rockies. Isolated populations are reported from Arizona and southern California. Appearance Pigeon tremex is a large (1½–2 inches) thick-bodied wasp. Females have a spikelike, dark brown ovipositor. Males, which are smaller, lack the projection. Adults are generally brown and yellowish, with patterning varying among different races throughout the range. Life History and Habits Adults are most commonly present in late summer, searching and probing recently killed and declining trees for egg-laying sites. As they probe trees, they also introduce a white rot fungus, Cerrina (=  Daedalea) unicolor, which rots and softens the wood for the developing larvae. Larvae feed for the next 8–9 months on the wood and fungi, creating tunnels that run through the heartwood. When full grown they create a pupal chamber just under the bark. The emerging adults cut through the bark, leaving a perfectly round exit hole. There is one generation per year over much of the range; the life cycle may take 2 years to complete in northern areas.

Other Horntails Several other horntails occur in North America that develop in conifers. Most abundant and widespread are Sirex species,1 the “sirex woodwasps.” These are blue-black wasps most often associated with pines that are in advanced decline or have recently been cut or killed. All carry white rot fungi, which the female introduces into trees through her ovipositor. Five species are native to North America, and a European species (Sirex noctilio) has recently become established in areas of the Northeast. Five species of Urocerus,1 which develop in recently killed fir and pine, also occur in North America.  Hymenoptera: Siricidae

1

Uroceras gigas. DAVID LEATHERMAN

450

B C

A. Pigeon tremex ovipositing into trunk.

A

WHITNEY CRANSHAW

B. Pigeon tremex male. DAVID SHETLAR

C. Pigeon tremex. WHITNEY CRANSHAW

D. Larvae of pigeon

tremex.

WILLIAM HANTSBARGER, COLORADO STATE UNIVERSITY

E. Circular exit holes

produced by pigeon tremex.

D

WHITNEY CRANSHAW

E

F. Blue horntail,

Sirex cyaneus.

F

WHITNEY CRANSHAW

G. Sirex noctilio female. DAVID LANCE, USDA APHIS PPQ, BUGWOOD.ORG

H. Sirex noctilio male. DAVID LANCE, USDA APHIS PPQ, BUGWOOD.ORG

I. Larva of Sirex noctilio. DENNIS HAUGEN, BUGWOOD.ORG

J. Sirex noctilio adult

at exit hole.

DAVID LANCE, USDA APHIS PPQ, BUGWOOD.ORG

G H

I

J

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

BARK BEETLES Bark beetles (Scolytinae subfamily within the weevil family Curculionidae) are fairly small beetles (ca. 1⁄16–¼ inch) that usually develop feeding on the cambium under the bark of trees. Adult beetles first cut distinctive galleries in which they mate and lay eggs. The legless, grublike larvae tunnel outward from these egg galleries. Feeding by the insects under the bark can girdle the tree, although most beetles limit attack to damaged limbs or trees that are stressed or in decline; newly transplanted trees are particularly susceptible to attack. However, many bark beetles are associated with fungi that can also produce diseases in trees. These include fungi in the genera Ophiostoma and Leptographium involved in Dutch elm disease and blue stain of conifers. Bark beetles that limit development to small branches and twigs are discussed in chapter 4.

Shothole Borer (Scolytus rugulosus)1 hosts Fruit trees (particularly Prunus spp.) and a few other hardwoods such as mountain-ash, English laurel, hawthorn, and in rare cases, elm. Most infestations involve overmature, damaged, or diseased plum and cherry. Damage Shothole borer is the most common bark beetle affecting fruit trees. Larvae develop under the bark, producing typical girdling wounds that can weaken and sometimes kill the plant beyond the damaged area. Oozing gum often occurs on Prunus species where beetles enter the wood to lay eggs. When the adult beetles emerge through the bark, they chew small exit holes, the most commonly observed evidence of shothole borer activity. Distribution An accidentally introduced species now found in temperate areas throughout North America. Appearance Adults are small (1⁄10 inch) gray-black beetles. Life History and Habits Shothole borer spends the winter as a grublike larva under the bark or as a pupa in chambers cut into the sapwood. Adults begin to emerge and become active in late April or May but can subsequently be found throughout the growing season. After mating, the females seek out wounded or diseased trees and chew out a 1- to 2-inch-long egg gallery, generally parallel to the grain. Eggs are laid in little niches along the gallery, and larvae subsequently feed under the bark. Adults exit through the bark, leaving a characteristic exiting shothole. Two to three generations may occur, depending on climate, although these are indistinct and egg-laying may occur through much of the growing season.

Related Species Hickory bark beetle (Scolytus quadrispinosus)1 attacks hickory, pecan, butternut, and walnut throughout much of the eastern U.S. and southeastern Canada. It is particularly damaging in southern areas of its distribution, where it is occasionally a serious forest pest. Some defoliation and leaf wilting may be present as newly emerged adults feed on twigs and leaf petioles. Egg-laying is limited to weakened trees. There is one generation per year in northern areas and two in the south.

452

A C

E

A. Shothole borer. NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

B. Shothole borer tunneling at base of twig. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Exit holes produced

by shothole borer.

JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Larval tunneling by shothole borer. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Shothole borer larva. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Egg gallery and larval tunnels produced by hickory bark beetle. DAVID SHETLAR

G. Hickory bark beetle. DAVID SHETLAR

G

D

F

B

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

BARK BEETLES

Smaller European Elm Bark Beetle (Scolytus multistriatus)1 hosts Elm. Damage This is the primary insect involved in transmission of the fungus that produces Dutch elm disease (Ophiostoma novo-ulmi). Larvae develop under the bark and can cause girdling injuries but usually restrict attacks to injured limbs or dying trees. There is little damage in the absence of the fungus. Distribution Most of the U.S. where elm is grown, except in some far northern areas. Appearance This beetle is generally dark and about ⅛ inch long with reddish-brown to reddish-black wing covers. Its posterior end is concave and has a small projection, or spine, typical of the genus Scolytus. Life History and Habits Smaller European elm bark beetles overwinter in the larval stage, in galleries under the bark. Larvae mature in the spring and pupate. Adult beetles typically emerge around mid-May, although earlier emergence may occur. Beetles emerging from trees infected with Dutch elm disease can become contaminated with spores of O. novo-ulmi. Transmission of Dutch elm disease by beetles occurs when the beetles subsequently fly to healthy elm trees, feed at the crotches of 2- to 3-year-old twigs, and subsequently contaminate the feeding wounds with spores of the fungal pathogen. This period, known as maturation feeding, may last for several weeks, during which eggs within the female mature. Adults then seek out diseased and weakened trees and construct egg galleries that run parallel to the wood grain. The larvae develop over the course of about 2 months, and adults emerge in mid- to late summer. Adults pass through a second round of twig-feeding and egg-laying, with the subsequent larval generation overwintering.

Other Elm Bark Beetles The banded elm bark beetle (Scolytus shevyrewi)1 is of Asian origin, first discovered in the U.S. in 2003, and has subsequently spread widely through much of western North America. It has a very similar life history to the smaller European elm bark beetle but typically emerges a few weeks earlier. In some areas of the Rocky Mountain region this insect seems to have largely eliminated S. multistriatus by competitive displacement. Native elm bark beetle (Hylurgopinus rufipes)1 is an important vector of Dutch elm disease in areas of the upper Midwest, northeastern U.S., and adjacent areas of southern Canada where cold temperatures limit the smaller European elm bark beetle. Many spend winter as adults that construct special chambers in the lower trunk. Egg galleries run across the grain.

454

A. Smaller European elm bark beetle tunneling into twig. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

B. Vascular discoloration

characteristic of infection with Dutch elm disease. WHITNEY CRANSHAW

A

C. Galleries produced by smaller

European elm bark beetle. DAVID LEATHERMAN

D.Larvae of the smaller European elm bark beetle. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Banded elm bark beetles

feeding on twig. WHITNEY CRANSHAW

F. Banded elm bark beetle

larvae in tunnels. WHITNEY CRANSHAW

G. Galleries produced by

banded elm bark beetle. DAVID LEATHERMAN

G H

B

C

D

E

H. Native elm bark beetle. JAVIER MERCADO, BARK BEETLE GENERA OF THE U.S., USDA APHIS ITP, BUGWOOD.ORG

F

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

BARK BEETLES

Ash Bark Beetles Three Hylesinus species1 may damage green and white ash. Eastern ash bark beetle (H. aculeatus) and Criddle’s bark beetle (H. criddlei) are generally distributed east of the Great Plains. Western ash bark beetle (H. californicus) is the most damaging species and found throughout much of the western U.S. and Prairie provinces. Ash bark beetles may infest almost the entire tree, from finger-diameter branches to the main trunk. Injured limbs and heavily shaded branches in the interior of the tree are most commonly attacked. Adult beetles cut egg galleries under the bark across the grain, and these typically have two arms with a central chamber. Small ventilation holes appear above the egg galleries. These injuries and subsequent tunneling by the larvae girdle branches. The tunnels are almost invariably colonized by fungi that stain the wood a rich brown color around the feeding sites. Ash bark beetles overwinter either as late-instar larvae under the bark or as adults in niches cut into the green bark of the outer trunk and become active in early to mid-spring. The larvae feed under the bark, often extensively scoring into the sapwood. Those developing from spring eggs become full grown in late spring or early summer and pupate in the tunnels. Adults emerge from the branch and feed on green wood, causing little damage. There is evidence that a partial second generation is sometimes produced. These may not complete development and overwinter as larvae. Bark beetles that have reached the adult stage move to the trunks at the end of the season to cut hibernation chambers in which they winter.

Southern Pine Beetle and Relatives (Dendroctonus spp.)1 Bark beetles in the genus Dendroctonus can be very damaging to conifers. They are typically small (ca. ⅛ inch) cylindrical beetles, dark brown or black. Thirteen species occur in North America, with many restricted to forest settings. Most Dendroctonus bark beetles can overcome tree defenses by mass attacks that are coordinated with chemical cues known as aggregation pheromones. Girdling of the tree results from egg galleries produced by the adults and larval tunnels under the bark. Many species are also associated with transmitting fungi that produce blue stain diseases that may contribute to tree death. Trees successfully attacked by Dendroctonus bark beetles typically show a fading of needle color, progressing to a reddish-brown color. These symptoms develop within a year after beetles begin to lay eggs and are almost always Views of southern pine beetle adult. followed by the death of the tree. ERICH G. VALLERY, USDA FOREST SERVICE–SRS-4552, BUGWOOD.ORG Southern pine beetle (D. frontalis) is the most important forest insect in the southeastern U.S., with Kentucky being part of its northern range. It is most commonly found on shortleaf, loblolly, Virginia, and pitch pines and is usually restricted to trees older than 15 years but with a trunk diameter less than 6 inches. Adult beetles usually enter the trunk 6–20 feet above ground and chew curved or S-shaped egg galleries. Multiple generations are produced, and a single generation may be completed in as little as a month during favorable warm periods. Adults may be active much of the time from spring through fall.

A

B

C

D

E

A. Eastern ash bark beetle, Hylesinus aculeatus. DAVID CAPPAERT, BUGWOOD.ORG

B. Ash bark beetle in egg gallery. DAVID LEATHERMAN

C. Ash bark beetle galleries

in branch.

WHITNEY CRANSHAW

D. Ventilation holes above

egg gallery of ash bark beetles in branch. DAVID LEATHERMAN

F

G

E. Hylesinus criddlei. JAVIER MERCADO, BARK BEETLE GENERA OF THE U.S., USDA APHIS ITP, BUGWOOD.ORG

F. Galleries in trunk produced by eastern ash bark beetle. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

G. Exit holes produced

by ash bark beetles. WHITNEY CRANSHAW

H. Pitch tubes produced in response

to attacks by southern pine beetle. ERICH G. VALLERY, USDA FOREST SERVICE–SRS-4552, BUGWOOD.ORG

I. Galleries produced by southern pine beetle. RONALD F. BILLINGS, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

J. Exit holes produced

by southern pine beetle. RONALD F. BILLINGS, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

H

I

J

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

BARK BEETLES Mountain pine beetle (D. ponderosae) is the most important bark beetle of western forests, particularly concentrated in the Rocky Mountains and Black Hills. It attacks primarily ponderosa, lodgepole, and limber pine; Scotch pine is occasionally damaged. Mature trees more than 8 inches in diameter are most susceptible to attack. Mountain pine beetle has a 1-year life cycle, with adults active during early summer. Two species of turpentine beetles are found in North America. Red turpentine beetle (D. valens) is the most widely distributed, occurring throughout the U.S. and southern Canada, excluding the southeastern and Gulf states, where black turpentine beetle (D. tenebrans) is found. Both species have similar habits and are among the largest bark beetles, with adults being ¼–⅜ inch long. They can develop in large-diameter pines and are particularly common in trees scorched near the base by fire or injured during construction. Turpentine beetle attacks are characteristically confined to the lower few feet of the trunk. Inner-bark feeding differs from that of most Dendroctonus, with larvae feeding as a group and excavating an irregular, round-edged patch under the bark. In mountainous areas of the western states, forest species sometimes become serious pests of landscape plants. Spruce beetle (D. rufipennis) historically has had several widespread and sustained outbreaks on Colorado blue and Engelmann spruce. Adults overwinter in small chambers cut into the base of the trunk and fly during June and early July. Larvae take almost 2 years to complete development.

Ips Beetles Ips beetles (Ips spp.),1 sometimes known as engravers, develop in most pines and spruce. At least one of the approximately two dozen Ips species that occur in North America is likely to be found wherever these hosts are found. Ips beetles are less aggressive than Dendroctonus bark beetles, usually limiting attacks to trees that are seriously stressed by root injury, drought, disease, or defoliation. Attacks are less commonly lethal to trees and may be limited to large branches or, most commonly, the tops of trees. Trees killed by Ips beetles show the uniform needle discoloration and death of Dendroctonus bark beetles. Blue stain fungi often, but not always, are introduced with Ips beetles. Adults are of typical size for bark beetles, ⅛–¼ inch long, and reddish brown to black. Characteristic is a pronounced cavity at the rear end lined with 3–6 pairs of toothlike spines. Ips beetles have multiple generations, and adults may be active whenever temperatures allow. Unlike many other bark beetles, Ips beetles are polygamous, with the initial tunneling by the male cutting a cavity under the bark (nuptial chamber). Attracted females subsequently produce characteristic patterns of egg galleries in the shape of Y or H. The egg galleries are free of sawdust, which is pushed out of the entrance hole by the scooped hind end of the beetles as they work. A yellowish- or reddish-brown boring dust in bark crevices or around the base of trees is indicative of ips beetle activity. SOME IMPORTANT IPS1 BEETLES OF LANDSCAPE CONIFERS SPECIES

HOST COMMENTS

Ips calligraphus Pine Ips pini Ips avulus Ips confusus Ips hunteri

Largest Ips beetle and known as six-spined engraver. Common throughout North America Throughout North America and often the most common species affecting pine. Known as pine Pine engraver Smallest Ips beetle and known as small southern pine engraver. Occurs in a broad area of eastern Pine U.S. south of Pennsylvania Pinyon Periodically kills pinyon over large areas An important species affecting Colorado blue spruce in Colorado and the southwest Upper Spruce portions of tree are typically infested first. Known as the blue spruce engraver. 458

D A

B

C

E H

F

G

I

A. Pitch produced in response

to attempted entry wound by mountain pine beetle. WHITNEY CRANSHAW

B. Egg gallery produced by mountain pine beetle. WHITNEY CRANSHAW

C. Galleries and associated staining

produced by mountain pine beetle.

WILLIAM M. CIESLA, FOREST HEALTH MANAGEMENT INTERNATIONAL, BUGWOOD.ORG

J

K

D. Blue stain fungi introduced during attack by mountain pine beetle. WHITNEY CRANSHAW

E. Dead and dying lodgepole

pine during mountain pine beetle outbreak. WHITNEY CRANSHAW

F. Red turpentine beetle. WHITNEY CRANSHAW

G. Larval tunneling by

red turpentine beetle. DAVID LEATHERMAN

L

H. Adult of the six-spined ips. NATASHA WRIGHT NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

I. Adults of the pinyon ips. WILLIAM M. CIESLA, FOREST HEALTH MANAGEMENT INTERNATIONAL, BUGWOOD.ORG

J. Galleries produced by six-spined ips. DAVID LEATHERMAN

K. Sawdust produced

by ips beetle tunneling. DAVID LEATHERMAN

L. Top dieback due to

infestation of spruce ips. WHITNEY CRANSHAW

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

AMBROSIA BEETLES Ambrosia beetles develop differently from other bark beetles. All tunneling is done by the adult female, which constructs a brood chamber in the sapwood or heartwood of trunks and branches. Small niches are often carved off a central chamber in which the larvae develop. Ambrosia beetles invariably carry into the brood chamber certain fungi (often Ambrosiella spp.) with which they have a mutualistic relationship. The fungi colonize the wood, and the larvae feed on the fungi (the ambrosia); larvae do no further tunneling. Damage by the native species of ambrosia beetles in the genera Trypodendron, Xyleborus, and Xyleborinus1 is usually minimal to living plants, as injuries are typically limited to nearly dead or recently felled trees. However, some introduced species in the genera Xylosandrus, Xyleborus, and Euwallacea1 have significantly greater potential to damage trees and shrubs, particularly when associated with fungi that are pathogenic to host plants. Recent research has indicated that smaller trees in waterlogged soils are most at risk of attack by introduced ambrosia beetles. Apparently, such trees produce alcohols that are attractants for the beetles. Granulate ambrosia beetle (Xylosandrus crassiusculus)1 tunnels into the sapwood and heartwood of a wide range of trees and shrubs, including various stone fruits (Prunus spp.), pecan, golden-rain tree, sweetgum, persimmon, Shumard oak, beech, Chinese elm, crape myrtle, and magnolia. Because of the site of tunneling, relatively little structural damage is done, but the activities of the beetle allow development of various cankerproducing fungi. Subsequent disruption of sap flow by these fungi can seriously damage and sometimes kill plants. Furthermore, affected plants are conspicuous, as wood particles produced by tunneling may project out of the trunk and branches as small sticks, often referred to as “toothpicks.” Granulate ambrosia beetle is dark reddish brown and about 1⁄10 inch long. Since its original introduction into Florida, it has spread throughout much of the southeastern U.S., as far west as Texas. One generation is thought to be produced annually, but adults are present year round, being most actively flying and attacking new plants in March and early April. Black stem borer (Xylosandrus germanus) is currently widely distributed through much of the eastern U.S., extending into parts of the Midwest and Texas. It has a wide host range of trees and shrubs, primarily broadleaf plants but also including some conifers. Tunneling causes wilting and dieback, particularly by contributing to the spread of cankers produced by Fusarium fungi. Adults emerge in March in southern areas of the range and in midMay farther north. The females bore into sapwood, constructing a brood chamber with branching side tunnels. The fungus (Ambrosiella hartigii) is introduced and begins to grow in chambers at this time. Eggs are then laid, and larvae can develop in about 1 month. Pupation occurs in the gallery, as does mating. The males, which cannot fly, do not leave the rearing chamber, but females then disperse to produce new brood chambers. Two generations per year are normally produced.

460

A B C

E D

F G

A. Tunneling of oak by a native Xyleborus ambrosia beetle. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

B. Xyleborus dispar. PEST AND DISEASES IMAGE LIBRARY, BUGWOOD.ORG

C. Adult granulate ambrosia beetle in tunnel. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

D. Compacted sawdust extruded from

tunnel of a granulate ambrosia beetle. DAVID SHETLAR

E. Larvae and pupae of granulate ambrosia beetle. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

F. Adult of the black stem borer. PEST AND DISEASES IMAGE LIBRARY, BUGWOOD.ORG

G. Damage to wood made by tunneling

of the black stem borer.

JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

INSECTS ASSOCIATED WITH L ARGE BR ANCHES AND THE TRUNK OF TREES AND SHRUBS

AMBROSIA BEETLES Black twig borer (Xylosandrus compactus) is a tiny (ca. 1⁄16 inch) beetle occurring in the southeastern states. It is considered among the most aggressively damaging of the ambrosia beetles and develops in the twigs of various trees and shrubs, including oak, maple, hickory, magnolia, and willow. Females construct a ½- to 1½-inch tunnel as a brood chamber in the pith or wood of succulent twigs, and numerous females may nest in larger twigs. Pathogenic fungi, including Fusarium solani, are commonly introduced during entry, and twigs usually die beyond the point of the tunneling. Larvae can develop rapidly, with a generation completed in a little more than a month. Redbay ambrosia beetle (Xyleborus glabratus)1 is an Asian species associated with a fungus (Raffalea lauricola) that can produce very severe injury, often death, of highly susceptible hosts in North America. It has been particularly destructive to native redbay (Persea borbonia) in the southeastern states where it first became established, and there is high concern about its potential to damage avocado. Xyleborus saxeseni, known variously as the “lesser shothole borer” and “fruit-tree pinhole borer,” is a very common insect associated with many hardwoods, including oak, walnut, peach, maple, and hackberry. Adults tunnel into the trunk and larger limbs of trees in decline or that have been recently felled and, upon entering the tree, create a tunnel directly into the sapwood, typically tunneling about an inch beneath the bark. Fine sawdust produced during the tunneling often accumulates at the entrance. The larvae develop as a group within the brood chamber, feeding on the ambrosia fungi that grow on the tunnel walls and expanding the chamber as they develop. As the female continues to lay eggs over a period of weeks, a mixture of life stages may be present. The primary injury produced by this insect is cosmetic blemishing of wood, affecting lumber quality. In addition to the pin holes created by tunneling, the area around the tunnels is darkly stained by fungi associated with the beetles. Anisandrus dispar,1 sometimes known as the “European shothole borer,” is a species that has long been established in North America but is at present particularly commonly encountered in the Pacific Northwest. The primary hosts are maple, ash, and oak. Recently, two Euwallacea species1 sometimes informally known as the “polyphagous shothole borer” and “Kuroshio shothole borer” have become established in parts of southern California. Both are associated with Fusarium fungi that can produce serious limb dieback in host plants and occasionally result in tree death. Highly susceptible hosts include boxelder, castor bean, avocado, English oak, California coast live oak, big leaf maple, silk tree, liquidambar, coral tree, titoki tree, California sycamore, and blue palo verde.  Coleoptera: Curculionidae (Scolytinae)

1

462

A A. Extensive tunneling

produced by redbay ambrosia beetle.

JAMES JOHNSON, GEORGIA FORESTRY COMMISSION, BUGWOOD.ORG

B. Sawdust tube produced

B C

by trunk tunneling of the redbay ambrosia beetle.

ALBERT (BUD) MAYFIELD, USDA FOREST SERVICE, BUGWOOD.ORG

C. Adult of the fruit-tree

pinhole borer.

PEST AND DISEASES IMAGE LIBRARY, BUGWOOD.ORG

D. Vascular staining produced by the fungus Raffalea lauricola introduced by the redbay ambrosia beetle. ALBERT (BUD) MAYFIELD, USDA FOREST SERVICE, BUGWOOD.ORG

E. Adult of Anisandrus

dispar.

KIRIN ELLIOT, OREGON STATE UNIVERSITY

D

F. Adult Anisandrus dispar with eggs. ROBIN ROSETTA, OREGON STATE UNIVERSITY

E

F

CHAPTER SIX

INSECTS AND OTHER INVERTEBRATES ASSOCIATED WITH ROOTS, TUBERS, SOIL, AND THE SOIL SURFACE Adults of the most common scarab beetles associated with turfgrass in eastern North America (l–r): May/ June beetle, green June beetle, European chafer, southern masked chafer, northern masked chafer, Japanese beetle, Oriental beetle, Asiatic garden beetle, black turfgrass ataenius. DAVID SHETLAR

WHITE GRUBS Scarab beetles (Scarabaeidae) are one of the largest families of insects, including some 1,400 species in the U.S. and Canada. Adults are generally heavy-bodied insects that vary widely in size and are known by names such as May/ June beetles, chafers, or dung beetles. Adults may or may not feed on leaves or flowers. Larvae, known as white grubs, are palecolored with a dark head and thick-bodied, usually assuming a C-shape when disturbed. Some species develop on the roots of plants, and these include the most important pests of turfgrass. Although general appearance of the various white grubs damaging lawns and garden plant is superficially similar, they often can be distinguished, on close examination, by differences in patterns of hairs (rastral pattern) on the tip of the abdomen and their mouthparts. The overwhelming majority of white grubs feed on animal manures, other decaying organic matter, and fungi. Many have important roles as macrodecomposers, essential in accelerating decomposition of organic matter and the cycling of nutrients.

Northern Masked Chafer (Cyclocephala borealis)1 hosts All managed turfgrasses, especially Kentucky bluegrass, perennial ryegrass. Damage Larvae destroy turfgrass roots and crowns as they burrow through the thatch which may kill plants. The presence of the grubs in lawns is also attractive to various vertebrate predators, notably skunks, raccoons, and birds, which further damage turfgrass while digging. Distribution Much of northeastern North America and southern Canada. Appearance Adults are dark yellow to light brown, about ½ inch long, with dark brown markings around the head. Life History and Habits The adults emerge in late June through July, flying at night, and are strongly attracted to lights. Adults do not feed. Mated females tunnel 4–6 inches into soil and lay about a dozen eggs at a time. Soil moisture is critical to egg development; at optimum, eggs hatch in about 3 weeks. The larvae move up to feed on organic matter that has accumulated near the soil surface where turf roots and crowns can also be destroyed. With cool temperatures they go deeper into the soil, returning to resume feeding in spring. Pupation occurs in late May and early June. 464

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G A. Larvae (white grubs) of the most common scarab beetles associated with turfgrass in eastern North America (l–r): May/June beetle, green June beetle, European chafer, masked chafer, Japanese beetle, Oriental beetle, Asiatic garden beetle, black turfgrass ataenius. DAVID SHETLAR

B. Masked chafer larva in root zone of grasses. DAVID SHETLAR

C. Life stages of the northern masked chafer. DAVID SHETLAR

D. Northern masked chafer adults mating on lawn. DAVID SHETLAR

E. Eggs of masked chafer. DAVID SHETLAR

F. Masked chafer grubs feeding on roots of turfgrass. DAVID SHETLAR

G. Lawn damaged by skunks digging

for grubs of masked chafers. JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Males of northern (left) and

southern (right) masked chafer. DAVID SHETLAR

H

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

whIte Grubs

Related Species There are approximately 20 Cyclocephala species in North America, but only a few are regularly damaging to turfgrass. Southern masked chafer (Cyclocephala lurida) is common from southern Pennsylvania to Nebraska and south. Species present in the western states include: southwestern masked chafer (C. pasadenae), present from west Texas to southern California; C. longula from Arizona and southern California; and western masked chafer (C. hirta), which occurs from western Kansas and Nebraska to California. The life history of these species is similar to that of northern masked chafer though western species in arid areas may emerge only after rainstorm events.

Other White Grubs Associated with Turfgrass European chafer (Rhizotrogus majalis)1 is an introduced species that has spread to scattered locations from Connecticut to Michigan and parts of southern Canada. Larvae feed on the roots of grasses and also shrubs such as arborvitae. European chafer appears to supplant Japanese beetle at some turfgrass sites with sandier soils. Adults feed little but sometimes attract attention when spectacular mating swarms move to trees at dusk on warm evenings in midJune. These large aggregations produce very little injury to trees, usually minor chewing along leaf margins. Later (late summer) the most serious damage to roots is produced by rapidly developing larvae. A 1-year life cycle predominates, but a small percentage of European chafers have been observed to require 2 years to complete development. Larvae of the Japanese beetle (Popillia japonica)1 are very important turfgrass-damaging white grubs in many eastern and midwestern states and southeastern Canada. In addition, the adult beetles feed and can seriously damage the leaves and flowers of a wide range of ornamental, fruit, and vegetable plants. The primary discussion of Japanese beetle is in the chapter on leaf chewing insects (page 202). May/June Beetles (Phyllophaga spp.)1 are among the largest of the white grubs, typically about ¾–1 inch long and stout-bodied. Adults are generally chocolate brown to nearly black. More than 200 species occur in North America, with about 25 reported to damage turfgrasses, garden plants, and field crops. The adults are active at night and may be seen careening around porch lights and bouncing off screens, often in late spring. The beetles feed on the foliage of various trees and shrubs, with oak a preferred host for many species, but this rarely results in any significant injuries. Much more significant damage results from the white grub larvae, which chew on plant roots. Grasses are most commonly damaged, but larvae can seriously injure roots of young trees and shrubs planted in grassy areas. Turfgrass injury produced by larvae of European chafer. DAVID SHETLAR

Damage to roots of yew by larvae of European chafer. DAVID CAPPAERT, BUGWOOD.ORG

A

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A. Adults of Western masked chafer. WHITNEY CRANSHAW

B. Adult European chafer. DAVID SHETLAR

C. Larva of a European chafer. DAVID CAPPAERT, BUGWOOD.ORG

D. Japanese beetle and eggs. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Comparison of size among three

turfgrass-damaging white grubs (l–r): Japanese beetle, European chafer, May/June beetle.

H

DAVID CAPPAERT, BUGWOOD.ORG

F. Adult May/June beetle. DAVID SHETLAR

G. May/June beetle feeding

on leaves at night. DAVID SHETLAR

I

H. Mating pair of May/June beetles. DAVID SHETLAR

I. Large numbers of May/June beetles following a mass emergence. JIM KALISCH, UNIVERSITY OF NEBRASKA

J. Larvae of a May/June beetle. WHITNEY CRANSHAW

K. Root damage to a seedling

tree by a May/June beetle larva. STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

J

K

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

whIte Grubs In northern areas, May/June beetles often have an extended life cycle that requires 3 years to complete. With these species, eggs are laid in the soil in May or June, and a limited amount of feeding takes place by young larvae during the first season, before they migrate downward for winter. They return to feed on roots and grow rapidly during the second season, producing most damage at this time. In the third year there is some additional feeding before the insects pupate in a belowground chamber. They transform to adults in late summer and early fall, ready to emerge the following year. Variations of May/June beetle life cycles occur, and in the southern U.S. many species complete development in a single season. Phyllophaga crinita, an important species in Texas, and P. latifrons, found in most Gulf States, have this habit. They commonly damage St. Augustinegrass, bermudagrass, and buffalograss. The lined June beetles (Polyphylla)1 is slightly larger than the Phyllophaga species of May/June beetles and many are marked by a series of white bands running the length of the body. Larvae develop on the roots of grasses, trees and shrubs, small fruits, and occasionally garden plants, but rarely are sufficiently abundant to cause serious damage. The life history is similar to that of May/June beetles, with adults feeding on foliage and larvae requiring 2 or more years to complete development. The insects are attracted to lights and often attract attention because of their large size, distinctive patterning, and because they may audibly hiss when disturbed. More than two dozen Polyphylla species occur in North America, most in the western states, and several (e.g., P. decemlineata, P. hammondi, P. variolosa, P. comes) are reported to occasionally damage turfgrass and landscape plants. Oriental beetle (Exomala orientalis)1 is an introduced species currently found in New England and the Mid-Atlantic States. In addition to turfgrass, larvae may damage roots of many nursery plants and small fruits, including plants grown in containers. Adults are about 2⁄5 inch, with the broad body form typical of scarab beetles. Coloration is highly variable, ranging from black to straw, with a wide range of patterned markings. Oriental beetles feed on flowers, notably daisy, but rarely cause much injury. Cotinus species are large (1¼ inches), brightly colored beetles, often iridescent green. C. nitidis (green june beetle) is an easily noticed species found throughout the southeastern U.S., ranging north to New York and west into Texas. C. mutabilis (fig eater beetle) is found primarily in the southwestern states. The larvae feed almost exclusively on dead or decaying organic matter. Occasionally they are associated with turfgrass and may cause minor injury through tunneling and production of small soil mounds. At night the grubs crawl to the surface to feed on grass leaf blades by flipping on their backs; they crawl in a unique manner by contracting and expanding their body segments. The legs, which are relatively small, are not used for locomotion. The larvae spend the winter as nearly full-grown grubs, resuming feeding in spring. Adults are present and active mostly in July and August. They are metallic velvety green with yellow-orange margins and a shiny green underside. In flight they may make a buzzing sound like bumble bees. They may feed and damage various thin-skinned ripe fruits such as apricot, peach, nectarine, plum, grape, pear, blackberry, raspberry, apple, and fig. This activity has resulted in a local common name of “fig-eater.” Sugarcane beetle (Euetheola humilis)1 is a shiny black beetle, about ⅞ inch long. This species is found from southern North Carolina over to Oklahoma and south. The adults can be attracted to night lights in considerable numbers. The larvae prefer soils with high organic matter content. Both adults and grubs can damage turfgrass, corn, wheat, strawberries, roses, and numerous other plants. The species is unusual among the other white grubs in that the adults generally spend the winter hiding in soil, usually under sod. In the spring, the adults lay eggs and the larvae develop rapidly to produce new adults in late summer. These adults feed at the base of plants before seeking hibernation sites. 468

A

B

C D

A. A tenlined June beetle, Polyphylla decemlineata. WHITNEY CRANSHAW

B, A lined June beetle

(Polyphylla species) without strong patterning. DAVID SHETLAR

C. Larva of a lined June beetle. WHITNEY CRANSHAW

D. Oriental beetle adults. DAVID SHETLAR

E. Green June beetles. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Larva of a green June beetle.

F

DAVID SHETLAR

G. Green June beetle larva

burrowing into lawn. DAVID SHETLAR

H. Soil mound produced

by a burrowing larva of a green June beetle. DAVID SHETLAR

I. A sugarcane beetle. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

I

G

H

E

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

whIte Grubs

White Grubs Associated Primarily with Garden Plants Carrot beetle (Tomarus gibbosus)1 is an occasional pest of root crops, producing gouging wounds. It is distributed throughout most of the southern and western U.S., from Texas and New Mexico east. Larvae are primarily grass feeders, and their presence in gardens is usually associated with a previous grass crop or the presence of grassy weeds. Adults sometimes damage plants by burrowing in soil and feeding on the roots and taproot of plants such as sunflower, dahlia, potato, beet, and carrot. Carrot beetle winters as an adult in the soil, and there is 1 generation per year. Asiatic garden beetle (Maladera castanea)1 is a species accidentally introduced into New England in the 1920s that has since steadily expanded its range. Presently it is known as far west as Michigan and Indiana, and to the south it occurs in the Carolinas. Larvae feed fairly deeply in the soil, about 2–3 inches, and are considered less damaging to turfgrass than species that feed closer to the surface; however, they are injurious to roots of flowers and vegetables and also develop on roots of many weeds. Hawkweed (Hieracium spp.) is a particularly favored plant in the Midwest. Adults emerge in late June and may be abundant in early summer. They feed at night on the leaves and flowers of more than 100 kinds of trees, shrubs, flowers, and vegetables, producing injuries similar to those produced by Japanese beetle. Asters, dahlias, chrysanthemums, and roses are reported as particularly damaged by this insect. Rain beetles (Pleocoma spp.) occur in western North America. Larvae are very long-lived, sometimes requiring 9–13 years to complete development. They feed on the roots of trees and shrubs, often around the base of the trunk, and can be particularly injurious to orchard crops. Pleocoma crinita, P. minor, and P. oregonensis are damaging species in the Pacific Northwest. Adults usually emerge in fall but are also active in spring. Only the males fly, and they seek females in their soil burrows, usually following rains. The mated female lays eggs throughout the following spring, in a spiraling pattern 10–30 inches deep in the soil. The larvae molt only once a year and may require a decade or more before they are ready to pupate. Because the females are flightless, rain beetles spread very slowly, but established populations can be difficult to control because of their unusual life history and deep burrowing habit. Sandhill chafer (Strigoderma arbicola)1 occurs in sandy soils in areas of the western Great Plains. Adults are the stage most often observed; they occasionally mass on foliage and flowers, where they are often referred to as “false Japanese beetles.” Larvae develop in the soil, feeding primarily on decaying organic matter but may move to tubers and roots late in the season, particularly when soil is dry. Larval stages of hoplia beetle (Hoplia callipyge)1 feed on decaying plant matter and roots of herbaceous plants, causing little damage. Adult stages, present in late spring, attract more attention as they feed on the blossoms of a wide variety of light-colored flowers. Hoplia beetle is most common in the Central Valley area of California. The bumble flower beetle (Euphoria inda)1 is a hairy-bodied scarab beetle most often seen feeding on pollen or on ooze from plant wounds. The larvae develop as scavengers of animal manure and plant matter, and they are often found in fresh compost or decaying mulch. Although they limit their feeding mainly to decaying organic matter, they have occasionally been observed to feed on living plant roots when favored food sources become depleted.  Coleoptera: Scarabaeidae

1

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D

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A

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A. Carrot beetle. NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

B. Asiatic garden beetles. DAVID SHETLAR

C. Larva of an Asiatic garden beetle. DAVID SHETLAR

D. Rain beetle. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Larva of a rain beetle, Pleocoma minor. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G I

F. False Japanese beetle. WHITNEY CRANSHAW

G. Larvae of hoplia beetle in roots of

strawberry.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

H. Bumble flower beetles visiting plant ooze. WHITNEY CRANSHAW

I. Larvae of bumble flower beetle

developing in compost. WHITNEY CRANSHAW

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

ROOT WEEVILS Several weevils1 develop on the roots of woody and herbaceous perennial plants. Root feeding can result in slow plant growth, secondary infection by plant diseases, and even death if the larvae girdle the stem of a plant. Adults feed aboveground on buds and leaves, rarely causing serious injuries. On leaves, their feeding characteristically appears as marginal notches. Adults of most root weevils, particularly those associated with ornamental plants, have fused wing covers and do not fly. Despite this, many species have spread widely in North America, primarily through the movement of infested plants with soil.

Black Vine Weevil (Otiorhynchus sulcatus)1 hosts A wide range that includes many shrubs. Hemlock, yew (where it may be called the taxus weevil), rhododendron, euonymus, other broadleaf evergreens, and many perennials are among those most seriously damaged. Damage Adult weevils feed on leaves at night, producing characteristic notching wounds along the leaf margin. When they are abundant, plants may be heavily defoliated. Larval stages feed on plant roots and in wet soils they may feed on the root-flair and girdle the plant. In areas of the Pacific Northwest and Midwest, this weevil is often considered the most important insect pest of nursery crops. Adults often lay eggs in potted plants set outside during the summer months. The adults are occasionally minor nuisance invaders of homes in late summer and fall. Distribution Native to Europe, now generally found throughout the northern U.S. and southern Canada. Appearance The adults are dark gray or black snout beetles, about ⅓ inch long with wing covers marked with gold flecking. Life History and Habits Black vine weevil spends the winter usually as a larva, in the soil around the root zone of plants on which it feeds. Occasionally some adults may survive winters if they find suitable shelter, including areas in and around homes. Larvae resume feeding in spring and can extensively damage roots in May and June. After becoming full grown they pupate in the soil, and adult weevils start to emerge in mid-June; only females are known to occur in North America. The adults feed on the leaves of various plants during the night, chewing characteristic notching wounds that somewhat resemble grasshopper injury. After about 2 weeks, the females begin to lay eggs around the base of plants. Eggs begin to hatch in midsummer, and the legless larvae feed on plant roots until cold weather temporarily stops development. One generation is produced per year.

Other Root-damaging Weevils Several Otiorhynchus species have been introduced into North America and, despite being flightless, some have become widely distributed. Leaf-notching injuries are particularly common by the lilac root weevil (O. meridionalis), which feeds on a wide variety of plants, including lilac, privet, peony, and apple. Strawberry root weevil (O. ovatus) and rough strawberry root weevil (O. rugosostriatus) are less commonly observed to produce leaf notching, but both can damage roots of many shrubs and perennials. Both are also common nuisance invaders of homes, usually entering buildings in greatest numbers during hot, dry weather in midsummer. The clay-colored weevil (O. singularis) is smaller and considerably lighter than the above species. It is occasionally important because of bud-feeding damage to raspberry in the Pacific Northwest. Adults are active in spring and early fall, going dormant in midsummer. 472

A

B C

D E

A. Black vine weevil. WHITNEY CRANSHAW

B. Black vine weevil larvae and damage to roots of yew. DAVID SHETLAR

C. Black vine weevil larvae. DAVID SHETLAR

D. Leaf notching wounds

produced by adult black vine weevil. DAVID SHETLAR

E. Strawberry root weevil. WHITNEY CRANSHAW

F. Lilac root weevil. WHITNEY CRANSHAW

F

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

rOOt weevIls Larvae of obscure root weevil (Sciopithes obscures)1 feed on the roots of rhododendron and can be very damaging to nursery stock in the Pacific Northwest and northern California. Adults feed on the leaves, chewing notches along the leaf margin. Adults are about ¼ inch, brown with a single wavy brown line near the rear, and present from August through October. The life cycle is similar to that of black vine weevil. Diaprepes root weevil (Diaprepes abbreviatus)1 has developed into a serious pest in parts of the southern U.S. since its introduction into south Florida in 1964. A native of the Caribbean, it has also been introduced into California and more recently found in Texas. Larvae develop on the roots of plants, and young plants may be completely girdled and killed directly. Often more important is that wounds allow development of root rots by Phytophthora fungi and other organisms. Diaprepes root weevil is estimated to do approximately $70 million of damage annually in Florida alone and is also a key citrus pest in Texas. It has a wide host range of more than 270 species, including citrus, other fruit crops, many woody ornamentals, and even some root crop vegetables. It is sometimes known as “citrus root weevil” or “sugarcane root stalk borer weevil,” reflecting its importance on these crops. Adults may be present year-round in south Florida but are active primarily from May through early November. Eggs are laid in clusters in leaves, and the newly hatched larvae subsequently drop to the ground and enter the soil. All subsequent larval development and pupation take place in the root zone. The life cycle is normally completed in 1 year but may be shorter in extreme southern areas. Although this species is a poor flier and disperses only short distances on its own power, it has been commonly moved about in infested soil. Two native species of blue-green citrus root weevils, Pachnaeus opalus1 and P. litus, are also part of the complex of root weevils damaging to citrus in Florida. Adults typically emerge in April and May, feed on leaves, producing leaf-notching injuries, then lay eggs at the base of the tree. In addition to citrus, the adults may feed on many other plants, and certain other plants, including peach, can be damaged by the larvae. Pachnaeus litus is restricted to Florida but P. opalus ranges to New Jersey. Arborvitae weevil (Phyllobius intrusus)1 is an introduced species found in the northeastern and MidAtlantic States. Adults feed on the new growth of arborvitae, northern whitecedar, and eastern redcedar. Primary damage is caused by larval feeding on roots and bark at the base of plants. Winter is spent as pupae in the soil, and adults are present in late spring, during which time eggs are laid. Arborvitae weevil is a black snout beetle with shiny green scales on the wing covers. A related, also introduced species is P. oblongus. Adults chew leaves of maple, elm, yellow birch, and serviceberry. It is known from New York west to Michigan. Pine root collar weevil (Hylobius radicis)1 most commonly attacks pines grown in plantations, but it can also be found in landscapes. The adult weevil is a mottled brown color, about ½ inch long. The legless larvae feed at and just below ground level on the sapwood. This feeding causes considerable pitch and sap flow that can infuse the surrounding soil. Attacks over multiple years can result in girdled trees or trees that easily break during windstorms. 1

Coleoptera: Curculionidae

474

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B

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A. Diaprepes root weevil. KEITH WELLER, USDA AGRICULTURE RESEARCH SERVICE, BUGWOOD.ORG

B. Larva of a diaprepes root weevil. DAVID ROSEN, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Larva of Pachnaeus opalus. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

D. Adult of the northern citrus root weevil, Pachnaeus opalus. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

E. Adult of the blue-green citrus

root weevil, Pachnaeus litus.

NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

F. Adult of Phyllobius oblongus. E. BRADFORD WALKER, VERMONT DEPARTMENT OF FORESTS, PARKS AND RECREATION, BUGWOOD.ORG

G. Adult of the pine root collar weevil. JENNIFER C. GIRON DUQUE, UNIVERSITY OF PUERTO RICO, BUGWOOD.ORG

H. Larva of the pine root collar weevil. JAMES B. HANSON, USDA FOREST SERVICE, BUGWOOD.ORG

I. Pupal chip cocoons and damage

by pine root collar weevil.

TERRY S. PRICE, GEORGIA FORESTRY COMMISSION, BUGWOOD.ORG

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

rOOt weevIls

Sweetpotato Weevil (Cylas formicarius)1 hosts Sweetpotato, morning glory, and related plants. Damage The most serious injury occurs from tunneling of the tuber by larvae. These wounds allow rotting organisms to further destroy the crop and induce bitter tastes in affected tubers. Tunneling of vines can cause wilting as well. Sweetpotato weevil is the most important pest of sweetpotato. Distribution North Carolina south through the Gulf States and into parts of east Texas. Appearance The adult is slender, almost antlike, and about ¼ inch long with a long beak. It is generally blue black with a bright red prothorax and legs. Life History and Habits Females chew a small pit into the lower stem or roots and insert a single egg, plugging the cavity with their feces. The larvae chew through the stem, working their way to the “tuber.” They feed for about 2–4 months depending on temperature, and then pupate in a chamber they cut in the plant. The adults may feed on the tuber or on the underside of leaves. Capable of flight, they may migrate in a series of short flights up to a mile, usually during the night. As many as 5–8 generations can be completed in a year. Development may occur throughout the year as long as temperatures and available food permit. 1

Coleoptera: Brentidae

Other Vegetable Weevils Carrot weevil (Listronotus oregonensis)1 can seriously damage carrot, parsley, dill, celery, and parsnip. Many related wild plants (Apiaceae family) are also hosts. Most often, larvae tunnel and riddle the roots, but they may also tunnel in aboveground shoots. The adults are tannish gray, about ¼ inch long, and become active early in spring. Eggs are laid in cavities chewed into leaf petioles. The young grubs tunnel into the stalks and work their way downward into the roots. They become full grown in about 3 or 4 weeks and pupate nearby in the soil. Two to three generations are produced over much of the range, although only one generation may occur in cooler northern areas. Carrot weevil occurs in much of southern Canada and the northern U.S. west of the Rocky Mountains, ranging into northern Texas and Georgia. Most damage has occurred in sites with soils high in organic matter. “Whitefringed beetle” is apparently a complex of three introduced and closely related Naupactus species1 that can be found in parts of the southern U.S. (N. leucoloma, N. minor, N. peregrinus). Adults are brownish gray snout beetles covered with fine hairs and sporting a pair of pale stripes along the thorax and sides of the abdomen. They can develop on a wide range of plants, with principal injury caused by the tunneling of larvae into roots and tubers. Legumes, okra, and sweetpotato are among the plants most seriously damaged. The life cycle takes a year to complete but is not well synchronized, so adult activity and egg laying can occur over an extended period, from early summer through mid-autumn. Overwintering stage can be eggs or, most typically, partially developed larvae. Strawberry crown borer (Tyloderma fragariae)1 is a small (3⁄16 inch), brown, flightless weevil. Adults lay eggs at the base of leaves and crown of strawberry plants and the larvae bore into and develop within the crown. Problems with this insect are infrequent and occur only where there has been sustained production of strawberries for a long period. There is one generation produced per year and the overwintering stage is adults. 1

Coleoptera: Curculionidae

476

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B

C

D

E

F

A. Sweetpotato weevil.

G H

CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

B. Damage by larvae of sweetpotato weevil. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Carrot weevil larva

in damaged carrot.

JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Adult carrot weevil. ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

E. Carrot weevil damage.

I

WHITNEY CRANSHAW

J

F. Carrot weevil tunneling

into stalks of celery.

ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

G. Whitefringed beetle. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

H. Damage to sweetpotato by larvae of whitefringed beetle. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

I. Strawberry crown borer. NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

J, Whitefringed beetle

larva in root.

K

TERRY S. PRICE, GEORGIA FORESTRY COMMISSION, BUGWOOD.ORG

K. Damage to strawberry crowns by

larvae of strawberry crown borer. JOHN C. FRENCH SR., UNIVERSITIES: AUBURN, GA, CLEMSON, AND MO, BUGWOOD.ORG

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

BLUEGRASS BILLBUG (Sphenophorus parvulus)1

hosts Primarily Kentucky bluegrass; occasionally fescues and perennial ryegrass. Damage Young larvae develop in the crown of grasses, often killing the plant. Older larvae move into soil and eat more crowns and roots. Peak injury occurs from late June to early August and is aggravated by drought stress. Grass stems killed by billbug larvae often break at the crown of the plant and show evidence of tunneling and a characteristic sawdust excrement at the wound. Distribution Throughout the U.S. and parts of southern Canada. Appearance Adults are slate gray to black weevils with a body about 5 ⁄16 inch long. Larvae are plump, legless grubs with a dark brown head; they are found either in the plant crown or in the soil about the roots. Life History and Habits Bluegrass billbug winters in the adult stage either in the thatch of lawns or in adjacent areas under sheltering mulch or leaves. It typically becomes active in mid- to early May, whenever soil temperatures reach about 65° F. Adults are often seen at this time crossing driveways and sidewalks, freezing or playing dead when disturbed. Females chew small holes in the base of grass stems and insert eggs. The young develop in the plant, tunneling down stems and into the crown area while leaving behind sawdust-like frass. As they outgrow the plant, they migrate to the soil and continue to feed on adjacent crowns or roots. Pupation occurs in the soil in early to middle summer. Adults are present in late summer, feed a bit on grass leaves, then move to wintering sites. Normally one generation is produced annually, although a small second generation has been noted in southern areas.

top: Larva of bluegrass billbug in stem of grass plant. DAVID SHETLAR

above: Hunting billbug larva in base of grass plant. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Other Billbugs In much of the southeastern U.S., hunting billbug (Sphenophorus venatus vestitus) is a common pest of zoysiagrass and bermudagrass. Although its life cycle and the injuries it causes are generally similar to those of bluegrass billbug, it is less synchronized, and most stages can be found throughout the year. This can also be said of Rocky Mountain billbug (S. cicatristriatus), a pest of Kentucky bluegrass in parts of the Rocky Mountain region and northern High Plains. Phoenix billbug (S. phoeniciensis) is associated with zoysiagrass and bermudagrass in the southwestern U.S. Sphenophorous coesifrons is moderately common in bermudagrass and St. Augustinegrass in the southeastern states. The little billbug (S. minimus), found in many areas east of the Mississippi, feeds on most cool-season grasses.  Coleoptera: Curculionidae

1

478

B C

D

A

A. Bluegrass billbug adult and larva.

E

DAVID SHETLAR

B. Life stages of the bluegrass billbug. DAVID SHETLAR

C. Egg of bluegrass billbug within

stem of grass plant. DAVID SHETLAR

D. Grass stems showing

chewing injuries produced by billbug larvae.

F

DAVID SHETLAR

E. Grass that broke at the crown

when tugged, due to billbug injury. DAVID SHTELAR

F. Symptoms of injury to lawn

G

due to bluegrass billbug. DAVID SHETLAR

G. Bluegrass billbug larva

in base of stem. DAVID SHETLAR

H. Older larva of bluegrass billbug in roots of turfgrass. DAVID SHETLAR

I. Hunting billbug. DAVID SHETLAR

J. Rocky Mountain billbug. DAVID SHETLAR

H

K. Phoenix billbug.

I

DAVID SHETLAR

J

K

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

WIREWORMS Wireworms1 are the larval stage of click beetles. Most wireworms are soil inhabiting and feed on roots of plants; some develop in decayed wood. The common name for the adults reflects their unusual ability to flip when laid on their back, often with an associated clicking sound. More than 880 species occur in North America, of which about two dozen may significantly damage crops. hosts Roots and seeds of a wide variety of plants. Root crops, including potato, carrot, and sweetpotato can be seriously affected. Damage Larvae tunnel into germinating seeds, roots, tubers, and other belowground structures. Small plants may be killed. Riddling injuries degrade the quality of root crops. Distribution Wireworms can be found throughout North America, although some species tend to be of limited distribution. The genera Ctenicerca and Limonius1 are concentrated in the west, particularly the Pacific Northwest. Conoderus1 species are found mostly in the southeastern U.S. Appearance Larvae are elongate, somewhat hard-bodied, and light yellow-brown. Adults are distinctive in having a greatly enlarged prothorax which is loosely jointed. Spines on the prothorax are structured in a way that allows it to abruptly snap quickly, causing the beetle to catapult; an audible ckicking noise is often associated with the snapping of the prothorax. Most species are gray or brown, although some patterning may occur on the wing covers. Life History and Habits Life cycles vary among species and locations. Most wireworms have a relatively long life cycle, with larval development extending several years, particularly if temperatures are cool. The exceptions are those in the genus Conoderus, found in the southeastern U.S., which may complete a generation within a year. Adults are usually most abundant in mid- to late spring. Eggs are laid shallowly in soils. Some species prefer to lay eggs in grassy areas, whereas others are attracted to moist soil regardless of nearby vegetation. The larvae are quite active and mobile in the soil. Pupation occurs in small cells constructed in soil.  Coleoptera: Elateridae

1

A. Wireworms. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Tobacco wireworm in plant stem. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

C. Wireworm larva next

to damaged onion.

ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

D. Wireworm damaged sweetpotato. GERALD HOLMES, CALIFORNIA POLYTECHNIC STATE UNIVERSITY AT SAN LUIS OBISPO, BUGWOOD.ORG

E. Tobacco wireworm adult. NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

F. Click beetle, adult of a wireworm. JIM KALISCH, UNIVERSITY OF NEBRASKA

480

B C

A D

E

F

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

WESTERN CORN ROOTWORM (Diabrotica virgifera virgifera)1 hosts Larvae develop solely on the roots of corn and a few types of grasses. Adults are leaf beetles that feed on corn silk and leaves, various flowers (particularly of cucurbits), and foliage of a wide variety of plants. Damage Larvae of the western corn rootworm develop on the roots of corn in early summer and can cause extensive pruning. This injury can reduce plant growth and also cause plants to fall (lodge) more easily following winds. Serious damage by this insect occurs over a wide area of the country, including all of the Corn Belt, and it is considered the most important pest of field corn in North America. Gardeners are more likely to observe the adult stages, which can be present on leaves and corn silks and within blossoms of squash family plants through the summer. Some damage occurs when large numbers of beetles prune the green silks, preventing pollination, resulting in poor set of kernels. Rarely, adults will also do some chewing damage to developing fruit of squash or pumpkin, although this damage is caused more commonly by other beetles (e.g., striped cucumber beetle, southern corn rootworm, checkered melon beetle) that may co-occur on these plants with western corn rootworm. Distribution The western corn rootworm has expanded its range and can now be found over a broad area east of the Rockies from Ontario to North Carolina. In Texas and Oklahoma a subspecies is present, known as the Mexican corn rootworm (D. virgifera zeae). Appearance The adult western corn rootworm is about ¼ inch long, with wings that are generally yellow and marked with indistinct dark stripes. Variation is considerable with the striping, and beetles can have 3 narrow stripes or wings that are largely dark with striping that has coalesced. Identification of this beetle is sometimes a source of confusion for gardeners as other beetles of similar size also have yellow wings with dark stripes, notably the striped cucumber beetle. The larvae are rarely observed by gardeners as they occur underground feeding on corn roots. They are creamcolored with a very elongate body and dark head. Life History and Habits Eggs of the western corn rootworm are laid during the summer in soil adjacent to corn plants. These eggs don’t hatch until the following May or early June. The tiny wormlike larvae move to growing corn roots. For about a month they feed, tunneling into roots, becoming full grown by early summer. Pupation occurs in the soil. Adults begin to emerge in early summer, primarily sometime in July. They feed on corn leaves, corn silks, and nearby flowers for about two weeks, then females will begin to lay eggs. Adult activity may extend into September, but most egg laying occurs in late July and August. One generation is produced per year.

Other Leaf Beetles that Develop on Roots and Tubers Northern corn rootworm (Diabrotica barberi) is uniformly green and slightly smaller than western corn rootworm. Habits and types of plant injury produced by this insect are similar to those of the western corn rootworm and normally restricted to corn. Northern corn rootworm has spread extensively from its origin in Colorado and the Dakotas so that it is now found eastward from Massachusetts to North Carolina.

482

A

B

C D

E

F A. Western corn rootworm. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Western corn rootworm larvae. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Western corn rootworm larva in corn root. JOHN CAPINERA, UNIVERSITY OF FLORIDA

G H

D. Root injury by western corn rootworm larvae. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Corn lodging from root damage by western corn rootworm. DAVID KEITH, UNIVERSITY OF NEBRASKA

F. Western corn rootworm adults in squash blossom. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Northern corn rootworm. DAVID SHETLAR

H. Larva of northern corn rootworm. DAVID SHETLAR

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

leaf beetles that develOP On rOOts and tubers Several other related beetles can be found in gardens. Southern corn rootworm (Diabrotica undecimpunctata howardi), also known as the spotted cucumber beetle, is slightly larger than western corn rootworm and marked with black spots on the wings. Larvae feed on roots of a wide number of plants, including corn and various squash family plants. Adults chew leaves, flowers, and developing seeds of many common garden vegetables and flowers. The western spotted cucumber beetle (Diabrotica undecimpunctata undecimpunctata) is a subspecies present in Pacific States with similar habits. Banded cucumber beetle (Diabrotica balteata) similarly has a wide host range, and larvae are known to damage several vegetable crops, including sweetpotato. It is a tropical species, restricted to areas of the southern U.S. where freezing temperatures are infrequent Striped cucumber beetle (Acalymma vittatum)1 can be a common insect associated with squash and melons east of the Rockies and has some superficial similarity to western corn rootworm. In the Pacific States the western striped cucumber beetle (A. trivittatum) is present and also strongly striped. Larvae of both develop on the roots of squash family plants; although these injuries normally cause little damage, extensive tunneling can occur that can lead to wilting and plant collapse. Greater plant losses occur when late-stage larvae migrate into the rind of ripening fruit, which sometimes occurs when soils get very moist near harvest. These “rindworms” produce surface scarring on the fruit where it is in contact with the soil, and these injuries not only cause surface defects that affect appearance but also provide entry points for decay and rotting pathogens. Ripe melons are at particular risk of these injuries. Three species of flea beetles in the genus Epitrix1 are associated with potato crops: potato flea beetle (E. cucumeris), western potato flea beetle (E. subcrinita), and tuber flea beetle (E. tuberis). Adults feeding on foliage produce shothole wounds in leaves; larvae develop belowground. Root-feeding injuries by larvae are generally considered insignificant, but after tubers form, larvae may cause surface scarring on them. This habit is most common, and the subsequent injuries most severe, with the tuber flea beetle, which occurs over a wide area of western North America. Larval tunneling may extend as much as ½ inch into tubers, and surface wounds result in tubers with scabby appearance. 1

Coleoptera: Chrysomelidae

left: Feeding damage to muskmelon rind by larvae of striped cucumber beetle and associated decay. WHITNEY CRANSHAW

below: Tuber flea beetle. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

484

A. Spotted cucumber beetle/southern corn rootworm. DAVID SHETLAR

B. Larva of spotted cucumber

A B

C

beetle/southern corn rootworm in plant root. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

C. Striped cucumber beetles. WHITNEY CRANSHAW

D. Tunneling at base of squash plant

by larvae of striped cucumber beetle. WHITNEY CRANSHAW

E. Banded cucumber beetle. FRANK PEAIRS, COLORADO STATE UNIVERSITY

F. Injury to potato tuber by

larvae of tuber flea beetle. WHITNEY CRANSHAW

G. Small wounds made in tuber

by tuber flea beetle larvae. WHITNEY CRANSHAW

D

F

G

E

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

PEACHTREE BORER (Synanthedon exitiosa)1 hosts Peach, cherry, plum, flowering almond, and most other Prunus species. Damage Larvae burrow into the base of trees at or just below ground level and sometimes enter larger roots. Feeding is in the form of irregular gouging wounds, that cretate gummy masses mixed with wood particles. These injuries weaken, girdle, and can eventually kill trees. Distribution Peachtree borer occurs throughout most of the U.S. and southern Canada. Appearance Larvae are cream-colored caterpillars, with a dark brown head. They are found within a wounded area in the base of the trunk or in root flares, under a mass of pitch. The larvae superficially resemble those of root boring beetles (e.g., roundheaded borers) but can be distinguished by having five pairs of short prolegs on the underside of the abdomen, each ringed with small hooks (crochets). Adults are day-flying moths that somewhat resemble wasps. The adult male is bluish black with yellow bands on the body and wings that are largely clear of scales except along the edge. Females have dusky-colored forewings and a broad orange band across the abdomen. Males can be monitored by using pheromone traps. Life History and Habits Adults emerge over an extended period that can range from late spring through early fall, but peak activity is typically during July and August. Females lay eggs on the bark of the lower trunk or on soil and weeds adjacent to it. Eggs hatch in about a week, and the larvae immediately burrow through the bark into the sapwood of the tree. Tunneling under the bark continues until late fall, with the insects mining down the trunk as cold weather approaches. With warmer weather, larvae resume feeding. Pupation occurs in a cocoon coated with excreted wood fragments, gum, and soil particles, usually just beneath the soil at the base of the trunk. Adults emerge in about 3 weeks. During emergence the pupal skin is often dragged to the soil surface at the base of the plant and can be useful in identifying infested plants and periods when adults may be active.

Peachtree borer males flying to pheromone baited trap. WHITNEY CRANSHAW

B C

D

A E

F

A. Damage at the base of tree due to peachtree borer. WHITNEY CRANSHAW

B. Peachtree borer

larva in root of peach. EUGENE NELSON, COLORADO STATE UNIVERSITY

C. Peachtree borer

in base of tree. DAVID SHETLAR

D. Peachtree borer

larva, ventral view showing prolegs.

G

DAVID SHETLAR

E. Peachtree borer

adult female.

DAVID LEATHERMAN

H

F. Pupal case of peachtree borer extruding from cocoon. DAVID LEATHERMAN

G. Peachtree borer

adult male.

WHITNEY CRANSHAW

H. Eggs of peachtree borer. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

IRIS BORER (Macronoctua onusta)2 hosts Bearded iris is the favored host, but other iris species can be attacked, especially if grown among bearded iris. Damage Iris rhizomes can be completely consumed, which results in sudden wilting or plant death in late summer. Poor growth and sprouting of small leaves is another symptom. During lifting and resetting of plants, growers often find that the rhizomes of favored plants have been largely destroyed. Distribution Iris borer is largely restricted to areas east of the Great Plains. Isolated areas outside this range have become infested as a result of movement of infested plant material. Appearance When larvae (caterpillars) are found in late summer, they can be 2 inches long and are cream, light gray, or even pinkish in color. They have brown head capsules. The moths are mottled gray and rarely seen. Life History and Habits Adult moths emerge from late August into October. After mating, females attach eggs to iris stems and rhizomes or to litter adjacent to iris plants. About the time that bearded iris begin to bloom, the eggs hatch and the tiny larvae burrow down the fold of a leaf. These early leafmining injuries often produce small “watermark” spots that can be useful for detecting incipient infestations. Over the next few weeks the growing larva burrows down the leaf stem and enters the rhizome, where it finishes its development. Eventually, the rhizome will be filled with wet frass pellets. After completing development, the larva burrows into the adjacent soil to pupate. The pupa takes 3-4 weeks to finish development.

Other Crown-boring Caterpillars Raspberry crown borer (Pennisetia marginata)1 develops within the cane bases or roots of raspberries, blackberries, and other Rubus. Adults emerge in early summer and somewhat resemble yellowjacket wasps. Eggs are laid on lower leaves and, at egg hatch, the larvae drop to the ground or tunnel into the cane and work their way to the base of the plant. Raspberry crown borer occurs broadly across North America but is more damaging in the northeastern U.S. and southern Canada. Two species of “hornet moths” occur in North America that also have adult stages resembling large yellowjacket wasps. Most widespread is Sesia tibialis,1 known as the cottonwood crown borer or American hornet moth. Larvae develop in the base of the trunk or exposed roots of cottonwoods and poplars. The insect has a large range, including much of the northern U.S. and southern Canada. A European species known as the hornet moth (S. apiformis) is established in some areas of the northeastern U.S. and develops in various species of Populus and Salix. Raspberry crown borer adult. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

488

A

B

C D

E

F G

A. Larva of iris borer. DAVID SHETLAR

B. Damage symptoms at base of plant by iris borer. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Iris borer adult. DAVID SHETLAR

D. Iris borer in stem. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Frass produced by

iris borer in stem.

JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Symptoms produced by young

H iris borer entering iris leaf.

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Raspberry crown borer

larva in base of plant.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H. Raspberry crown borer larva. UNIVERSITY OF GEORGIA PLANT PATHOLOGY, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

crOwn-bOrInG caterPIllars Grape root borer (Vitacea polistiformis)1 is one of the most damaging clearwing borers. Larvae develop as a crown borer of grape and often also damage roots. Smaller roots can be completely killed by these injuries, and damage to larger roots can greatly decrease growth and yield of plants. Grape root borer occurs throughout much of the eastern U.S. but is most damaging in more southern areas. Virginia creeper may be similarly damaged by two species of “Virginia creeper clearwings” that develop as crown borers, Albuna fraxini1 and Vitacea scepsiformis. Albuna fraxini is known primarily in the midwestern and northeastern U.S. but has been reported in Colorado. Vitacea scepsiformis occurs throughout the eastern half of the U.S., ranging into Florida. Boston ivy is also a reported host of the latter. Several other clearwing borers develop as root and crown borers of herbaceous perennials. Albuna pyramidalis1 develops as a root borer of certain Epilobium and Oenothera. It is present across the northern U.S. and southern Canada with a range that extends southward along the Rocky Mountain and Pacific Mountain ranges. Euhagena nebraskae1 also feeds on Oenothera in the southwestern states. Carmenta corni1 develops in the roots of Aster, Veronica, and Eurybia macrophylla and is presently known from an area extending from Wisconsin and Ontario eastward. Three species of Penstemonia1 are present in the western U.S. (P. clarkei, P. dammersi, P. hennei), all of which develop as root borers of Penstemon. Strawberry crown moth (Synanthedon bibionipennis)1 develops in the crown of strawberries. Other hosts include Potentilla, Rosa, and Rubus. It is present primarily in the Pacific States, but some localized records occur in the eastern U.S Strawberry crownminer (Monochroa fragariae)3 tunnels the crowns, buds, and young leaves of strawberry. It is found primarily in the Pacific Northwest, but isolated infestations occur elsewhere from movement of infested plants. Larvae, reddish with a dark head, are somewhat similar to those of peach twig borer. In the southeastern states, ranging to parts of Texas, convict caterpillar (Xanthopastis timais)2 develops on the rhizomes, bulbs, and foliage of various lilies. The adult form, known as Spanish moth, has a black body and wings patterned with black and yellow-orange on a rosy background. Eggs are laid in masses, and the larvae originally feed as a group on foliage. Multiple generations can be produced throughout the year when temperatures permit. 1

Lepidoptera: Sesiidae; 2 Lepidoptera: Noctuidae; 3 Lepidoptera: Gelechiidae

490

A. Damage to the base of grape by grape root borer. JAMES SOLOMON, USDA FOREST SERVICE, BUGWOOD.ORG

B. Larva of grape root borer. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

C. Adult of grape root borer. DAVID SHETLAR

D. Larva of Albuna fraxinii in base of Virginia creeper. WHITNEY CRANSHAW

E. Adult of Albuna fraxinii. WHITNEY CRANSHAW

F. Strawberry crown moth. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G. Strawberry crown moth

A

larva in base of plant.

B

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C D

E

F

G

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

SUBTERRANEAN AND SURFACE-FEEDING CUTWORMS Most of the caterpillars that forage at the soil surface or within the root zone of plants are various types of cutworms. This term is rather loosely applied to several caterpillars of the family Noctuidae. They are of moderately large size, typically well more than an inch when full grown, and have a body lacking hairs. Species that feed belowground or under litter are known as subterranean cutworms, while those active around the soil surface are usually called surface feeders. Most of the larvae are dull-colored and all are active at night, hiding in soil during the day. Other cutworms spend considerable time feeding on foliage, buds, or other aboveground plant parts. These are collectively known as climbing cutworms and discussed in chapter 2 with other foliage-chewing insects.

Black Cutworm (Agrotis ipsilon)1 hosts Black cutworm can feed on a very wide range of plants, including seedling stages of most garden plants and many grasses, including corn. Damage Black cutworm feeds at the surface at night, and late-stage caterpillars often cut seedling plants near ground level; Tthey may consume these in place or pull them a short distance into a soil burrow. They are also common in turfgrass and are particularly damaging to bentgrass golf greens, where their feeding produces irregular, chewed sunken areas on the surface. Distribution Black cutworm is primarily a subtropical and tropical species that fails to survive winter except in the warmest areas of the U.S. The adult moths, however, are strongly migratory and may fly from Central America to cover broad areas of the U.S. and southern Canada by summer. Appearance Black cutworm moths have a wingspan of about 2 inches with wings that are gray to brown with a black daggerlike marking on the forewing. The caterpillars are fairly uniformly colored, from gray brown to nearly black with a somewhat greasy sheen. Black spots surround the spiracles along the sides. Life History and Habits Black cutworm lays eggs at night in small clusters on foliage of broadleaf plants or singly on the tips of grass blades. Caterpillars feed at night, with early stages feeding on foliage. They begin to cut plants after the second molt (third instar), pulling the cut pieces into shelters of soil cracks or surface debris. The entire life cycle is completed in about 2 months. One or two generations commonly are completed in northern areas, three or four in the south.

492

A

B

C D

E

F

G

A. Cutworm at base of damaged onion.

F. Black cutworm and damage to corn.

WHITNEY CRANSHAW

JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Larva of the black cutworm. DAVID SHETLAR

C. Black cutworm adult. DAVID SHETLAR

D. Egg of black cutworm. DAVID SHETLAR

E. Black cutworm damage

to golf course green. DAVID SHETLAR

H

I

G. Army cutworm larva. FRANK PEAIRS, COLORADO STATE UNIVERSITY

H. Army cutworm pupa. WHITNEY CRANSHAW

I. Army cutworm adults. WHITNEY CRANSHAW

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

OTHER SURFACE-FEEDING AND SUBTERRANEAN CATERPILLARS Army cutworm (Euxoa auxiliaris)1 is the most important cutworm in the High Plains and Rocky Mountain region. Overwintering larvae resume feeding in spring and feed on a wide range of plants, preferring broadleaf plants over grasses. Emerging garden plants may be cut at this time, and army cutworm can contribute to spring lawn thinning when it occurs together with sod webworms and bronzed cutworm. Pupation occurs in the soil following the spring feeding peak. The life cycle of the army cutworm exhibits an unusual feature after the adults begin to appear in late April and May. These are grayish-brown moths with wings marked with numerous light spots and kidney-shaped markings that have a highly variable pattern. The adults become migratory at this time, but reproduction remains suspended. The adults seek out nectar and pollen sources on which to build fat reserves and follow flowering plants to high elevations. These migrations often cause them to pass through population centers, particularly near foothills, and the migratory army cutworm is locally well known as the “miller moth.” In summer, army cutworm moths occur in mountainous areas where they alternately feed on nectar and rest in crevices, under rocks, and in other sheltered locations. After building up fat reserves during summer, a reverse migration back to the lower elevations occurs in September and October. Eggs are laid at this time and the larvae feed in fall and through winter as temperature conditions allow. Bronzed cutworm (Nephelodes minians)1 occurs in the northern U.S. and southern Canada east of the Rockies. It is common in bluegrass and ryegrass lawns and may cause considerable thinning during peak feeding in late spring. Larvae have five white or yellow stripes running the length of a generally bronzy colored body. Bronzed cutworm has an appearance generally similar to armyworm (Mythmia unipuncta), another insect that may occur in turfgrass, but its distinct metallic sheen distinguishes it, as does its habit of early spring feeding. Pupation occurs in the soil and persists through summer, with adults emerging in late August and September and laying eggs. Some eggs hatch in the fall and the larvae can feed under the cover of snow while other eggs hatch in early spring. Redbacked cutworm (Euxoa ochrogaster)1 is often the most abundant cutworm in the far northern U.S. and southern Canada. Larvae can be distinguished by their brick red stripes on the back, separated by a light line. They feed at night, cutting small plants, but sometimes they climb. Broadleaf plants are most commonly damaged, including a wide variety of vegetables and even buds of some fruits. Outbreaks are cyclical and usually follow periods of dry weather. Darksided cutworm (E. messoria)1 also occurs through southern Canada and the northern U.S. but is rarely damaging. Larvae feed on leaves and stems of young plants in late spring, sometimes producing stand losses. Adults of both species are active in late summer and lay eggs in loose soil. Egg hatch occurs in spring. The name dingy cutworm also appears to be applied to a species complex of grayish-brown caterpillars including Feltia jaculifera,1 F. subgothica, and others. Winter is spent as partially grown larvae that resume feeding in spring and are most damaging as surface cutters of seedling plants. Pupation occurs in the soil, and adults are present in late summer and early fall. Eggs are usually laid in areas of dense vegetation. The larvae feed for a while before going dormant for the winter. Dingy cutworm occurs throughout North America.

494

A A. Bronzed cutworm. DAVID SHETLAR

B

C

B. Armyworm. DAVID SHETLAR

C. Bronzed cutworm adults. DAVID SHETLAR

D. Redbacked cutworm. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Darksided cutworm. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Darksided cutworm pupa cutworm. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G. Dingy cutworm. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H. Dingy cutworm adult. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D

E

G H

F

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

surface-feedInG and subterranean caterPIllars Glassy cutworm (Apamea devastator)1 is a pale, cream colored caterpillar generally found in soil or the crown area of grasses. Winter is spent as partially grown larvae, and they may continue to feed and develop during sufficiently warm periods in winter, often in co-occurrence with sod webworm larvae (page 122). Larvae mature in spring and adults begin to emerge in late June. Eggs are laid throughout summer at the base of grasses, and larvae hatching from the eggs will feed until cold weather prevents activity. Glassy cutworm occurs over most of the U.S. and Canada, excluding the southeastern states, but is most often encountered in northern parts of its range, including the Prairie Provinces and Pacific Northwest. Potato tuberworm (Phthorimaea operculella)2 develops on various nightshade family plants, including potato, tomato, and tobacco. Larvae develop as leafminers, primarily of young leaves, and will also bore into stems and petioles. Much more damage occurs when larvae move into potato tubers that are exposed or accessible through soil cracks. Tuber feeding is often concentrated around the eyes but extensive tunneling can occur. Furthermore, reproduction of potato tuberworm can continue in potatoes in storage. The potato tuberworm is not tolerant of cold temperatures and rarely survives outdoors in areas with freezing winters but can survive indoors on tubers and in very protected sites. Cranberry girdler (Chrysoteuchia topiaria)3 is a sod webworm of unusual habit. It feeds primarily in the crowns and upper root system rather than on leaves. Damage is not limited to grasses, with runners of cranberry and taproot of seedling Douglas-fir among the plants that can be seriously damaged. Peak injury occurs much later in the season than is observed with other sod webworms, typically in September and October. Reflecting their subterranean feeding habit, the larvae lack the dark markings of most sod webworms and are instead pale-colored with a light brown head. Larvae of the grass tubeworm moths (Acrolophus spp.),4 also known as “burrowing sod webworms,” typically produce a silk-lined burrow in the soil, emerging at night to feed. Little detail is known of the life history and feeding habits of tubeworm moths (53 North American species), but some associated with lawns are reported to feed on roots of grasses and clovers as well as plant debris in the thatch. 1

Lepidoptera: Noctuidae; 2 Lepidoptera: Gelechiidae; 3 Lepidoptera: Crambidae, 4 Lepidoptera: Acrolophidae

A. Glassy cutworm. DAVID SHETLAR

B. Potato tuberworm larva in potato. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Cranberry girdler larva. DAVID SHETLAR

D. Cranberry girdler larvae in root area of lawn. DAVID SHETLAR

E. Surface entrance to tunnel produced

by larva of a grass tubeworm moth. DAVID SHETLAR

F. Cranberry girdler adult. DAVID SHETLAR

G. Tunnel produced by larva

of a grass tubeworm moth. DAVID SHETLAR

H. Grass tubeworm moth. DAVID SHETLAR

496

A

B

C D

E

F

G H

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

ROUNDHEADED BORERS THAT FEED ON ROOTS The largest insects of North America that develop in plant roots are various beetle larvae of the genus Prionus1 sometimes known as giant root borers. Adults are dark brown to nearly black and typically range from 1½ to 2 inches in length. The antennae are prominent and in the males, particularly enlarged and characteristically serrated. Eggs are laid in soil at the base of trees, and the larvae develop by tunneling roots of various hardwood trees, particularly oak and nut trees. Apparently healthy trees can be injured, and sometimes significant structural weakening is produced by the tunneling. Larval development is also quite extended, often requiring 3 or 4 years to complete. Tilehorned prionus (P. imbricornis) predominates in the eastern half of the U.S., where it can be found on roots of oaks, chestnut, pecan, grape, and some fruit trees. Its range overlaps considerably with that of the broadnecked root borer (P. laticollis), which has a somewhat broader host range but is most often found on oaks, poplars, chestnut, grape, or apple. These are replaced in western North America by California prionus (P. californicus), which also has a wide range of hosts, including oaks, madrone, serviceberry, apple, poplars, eucalyptus, and some conifers. Several other Prionus species are root borers of rangeland grasses or shrubs. Cottonwood borer (Plectodera scalator)1 is a large longhorned beetle prominently marked by dark checkered markings on a light-colored body. Willow, cottonwood, and poplar are hosts, and sometimes these are seriously riddled by larval tunneling. During heavy infestations, smaller trees may be severely weakened and break at the base. Adults are active in late spring or early summer and feed on tender young shoots. Eggs are then deposited in pits chewed in the bark at the tree base. Larvae hatch and feed in the phloem, progressing downward into larger roots during their first fall. They spend the second summer feeding in galleries at the tree base. The life cycle requires 2 years to complete. The bumelia borer (Plinthocoelium suaveolens)1 is a very brightly colored beetle, metallic green with orange-red legs, most often seen feeding on the flowers of gum bumelia (Sideroxylon) in early summer. Larvae develop as borers in the root crown area. Bumelia is the most common host, but tupelo and mulberry are other reported larval hosts. Another very brightly colored species that occurs over a wide area of eastern North America is elderberry borer (Desmocerus palliatus),1 which develops within the lower stems and later moves to the roots of native elderberries. Both these beetles are most often observed on flowers, feeding on pollen. Several conspicuously colored longhorned beetles in the genus Tetraopes,1 that are known as “milkweed longhorns,” are associated with milkweeds. Some may feed on a single milkweed species, while others are capable of development on two or more milkweed species. Tetraopes femoratus has the most widespread range in the U.S., absent only from areas in the southeast. Tetraopes tetrophthalmus is often the most common species in the midwestern and northeastern states, while T. texanus is a common representative of the south-central states. Adults spend almost all their time on milkweed, where they rest, feed, and mate. Feeding by the adults can occur on all aboveground parts of the plants, particularly young leaves, flower buds, and blossoms. Eggs are laid in the area of the root crown. The larvae then tunnel into soil or make shallow tunnels into the epidermis of the stem while migrating to the roots. Larval development occurs on the roots. 1

Coleoptera: Cerambycidae

498

B C A

D

E

G H

F A. Tilehorned prionus. DAVID SHETLAR

B. Larva of a Prionus species. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

C. Tunneling at crown

of tree produced by a larva of a Prionus species. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

D. Pupa of Prionus species. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

E. Male (left) and female (right)

of the California prionus. WHITNEY CRANSHAW

I

F. Cottonwood borer.

J

WHITNEY CRANSHAW

G. Larva and root tunneling

of cottonwood borer.

JAMES SOLOMON, USDA FOREST SERVICE

H. Adult of the bumelia borer. RONALD F. BILLINGS, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

I. Mating pair of the milkweed longhorn Tetraopes tetrophthalmus. DAVID SHETLAR

J. Elderberry borer. DAVID SHETLAR

K

K. A milkweed longhorn,

Tetraopes femoratus. WHITNEY CRANSHAW

L. Larva of the milkweed

L

longhorn, Tetraopes femoratus. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

ROOT MAGGOTS AND BULB FLIES Larvae of several families of flies develop on belowground parts of plants. Most damaging are the various root maggots that develop by feeding on roots and germinating seeds of garden plants. Bulb flies are members of the flower fly family (Syrphidae), a group that includes many highly beneficial predators of aphids and other plant pests (page 624). Those that develop on bulbs are usually fairly stout-bodied flies that can resemble bees.

Cabbage Maggot (Delia radicum)1 hosts Most commonly grown crucifers (cabbage family), including rutabaga, broccoli, radish, cabbage, cauliflower, and Chinese cabbage Damage The larvae feed on roots, which can stunt and sometimes kill developing plants. Root crops (turnip, rutabaga, radish) are directly damaged through scarring of the roots. During periods of extended dry weather, the damage may occur aboveground to the base of leaves. Distribution Generally throughout Canada and the northern half of the U.S. Appearance Adults are typical of this genus: moderate-sized (ca. ¼ inch) gray flies, somewhat resembling small house flies. Dark stripes are present on the thorax. Larvae are pale, rather plump maggots that feed within roots of host plants. Pupae develop in a smooth, dark brown covering of rather seedlike form, known as a puparium. Life History and Habits Winter is spent in the pupal stage in soil. Adults emerge in mid- to late spring. Eggs are laid in masses, usually in soil cracks at the base of plants. Larvae develop over the course of 3–4 weeks, with a generation being completed in about 2 months. Two and often three generations occur per year, although injury tends to be greatest early in the season.

Other Root Maggots Radish root maggot (Delia planipalpis) also develops on roots of crucifers, including radish, turnip, cabbage, Chinese cabbage, and various mustard-family weeds. It is western in distribution, found from Alaska to California. Seedcorn maggot (Delia platura) is probably the most widespread of the root maggots found in North America. Larvae develop on seeds and seedlings, preventing successful emergence or wounding seedlings, particularly at the growing point. Damage is most common on warm-season plants with large seeds such as corn, bean, and melon. Cool weather and the presence of decaying organic matter are sometimes associated with greater injury. Seedcorn maggot may also be found as a secondary pest on plants damaged by disease. Of very similar habit and commonly mistaken for seedcorn maggot is bean seed maggot (D. florigela), common in the northern U.S. and Canada west of the Rockies. Onion maggot (Delia antiqua) develops on roots of onion, garlic, leek, and many related plants. Larval tunneling can cause plants to wilt and die, either directly from injury or by facilitating rotting organisms. This species also readily invades decaying onions. It is widely distributed in the northern U.S. and southern Canada, particularly in areas where soils are high in organic matter.

500

C A

B

E

F

D

A. Damage to turnip by cabbage maggot. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

B. Cabbage maggot female. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G H

C. Cabbage maggot larva. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Eggs of cabbage maggot laid in soil crack. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Cabbage maggot pupae. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Seedcorn maggot larvae in

destroyed corn seed.

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Symptoms of green beans

damaged by seedcorn maggot. WHITNEY CRANSHAW

H. Seedcorn maggot

larvae in bean seedling. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

I. Onion maggot male.

I

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J. Eggs of onion maggot

laid in soil crack.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

K. Root maggot larva in

base of onion plant. WHITNEY CRANSHAW

L. Onion maggot larvae

in developing onion bulb.

J

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

K

L

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

rOOt MaGGOts and bulb flIes Sugarbeet root maggot (Tetanops myopaeformis)2 is an important pest of sugarbeet in the Great Plains and Rocky Mountain states. It is also sometimes a pest of summer-grown spinach and garden beet in the region. Larvae tunnel the roots and allow decay organisms to enter, causing wilting of the entire plant. One generation is produced annually, with the overwintering stage being full-grown larvae in soil. The emergence and activity of adults can be observed by the adults’ tendency to aggregate on telephone poles and other prominent objects around previously infested fields.

Narcissus Bulb Fly (Merodon equestis)3

Spinach wilting due to damage by sugarbeet root maggot. WHITNEY CRANSHAW

hosts Narcissus, daffodil, hyacinth, amaryllis, lily, tulip, and some other bulbs are occasionally infested. Damage Narcissus bulb fly tunnels into the base of bulbs, weakening or killing the plants and making the bulbs susceptible to rot. Distribution Narcissus bulb fly is a European species that has become generally distributed across North America through movement of infested bulbs. Appearance Larvae are plump, off-white, and markedly wrinkled maggots found in bulbs. Adults are hairy flies, similar in size and color to large honey bees or small bumble bees. Life History and Habits This insect spends the winter as a large Eggs of narcissus bulb fly. KEN GRAY COLLECTION, maggot inside the bulb. It pupates the following spring, and the adult fly OREGON STATE UNIVERSITY emerges around mid- to late May, shortly after blooms have passed. Female flies lay eggs in soil cracks around the plant stems for a month or two after the flowers have died back. The newly hatched maggots crawl down the plant stem and tunnel into the base of the bulb. They continue to feed throughout the summer, becoming full grown in the fall.

Other Bulb Flies Onion bulb fly (Emerus strigatus)3 and lesser bulb fly (E. tuberculatus) also are European species that can now be found throughout North America. Larvae are often associated with bulb or root decay of narcissus, hyacinth, amaryllis, onion, shallot, and iris. Adults are about ¼ inch, bronze or dark green with yellow banding on the abdomen. Larvae are dirty white, wrinkled, with a brown respiratory tube on the hind end. Multiple larvae can infest a single bulb. Infested bulbs may die or send out only a few small leaves.  Diptera: Anthomyiidae; 2 Diptera: Otitidae; 3 Diptera: Syrphidae

1

502

A. Sugarbeet root maggots in roots of spinach. WHITNEY CRANSHAW

B. Adults of the sugarbeet

A

B

root maggot.

WHITNEY CRANSHAW

C D

E

F

G

H

J

C. Narcissus bulb fly

larva in daffodil bulb. WHITNEY CRANSHAW

D. Narcissus bulb fly. DAVID SHETLAR

E. Narcissus bulb fly. WHITNEY CRANSHAW

F.Narcissus bulb fly

pupa in daffodil bulb. WHITNEY CRANSHAW

G. Bulb fly adult. WHITNEY CRANSHAW

H. Damage produced by larva of the lesser bulb fly. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

I. Larva of the lesser bulb fly. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J. Mating pair of

bulb flies.

DAVID SHETLAR

I

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

CARROT RUST FLY

(Psila rosae)1

hosts Primarily carrot; occasionally celery, parsley, dill, coriander, celeriac, and fennel Damage Larvae mine roots of carrot, particularly the lower third. Young plants may be killed. Older carrots sustain scarring, with burrows often a rusty red color. Wounds can promote rot. Distribution Scattered areas throughout the northern U.S. and southern Canada Appearance The adult is a small (1⁄5 inch), thin-bodied black fly with yellowish legs and a reddish-yellow head. Larvae are creamy white, of typical tapered maggot form. Life History and Habits Carrot rust flies winter in soil as pupae but occasionally as larvae in roots. Adults emerge in late April to mid-May. Eggs are laid around the base of plants and hatch in 1–2 weeks depending on temperature. Pupation occurs in soil near infested plants. Feeding by larvae on the roots follows, after which there is a second generation, with adults laying eggs in late July and August. A small, third, early-fall generation is also reported in some areas. 1

Diptera: Psilidae

EUROPEAN CRANE FLY

(Tipula paludosa)2

hosts Various grasses; occasionally some vegetables, flowers, and strawberry Damage Larvae chew roots and crowns of turfgrass, seedling trees and shrubs, and vegetable crops and also disturb plants with their extensive soil tunneling. In turf, damage appears as a general thinning or as pockmarks on golf greens. European crane fly is the most damaging turfgrass insect in the Pacific Northwest. Distribution This is an introduced species, and its range has slowly spread since its introduction around 1965. It is presently known to occur over much of the Pacific Northwest, in Quebec and Ontario Provinces, Michigan, New York, and some New England States. Appearance Larvae are generally cylindrical, legless, and slightly tapered at either end. The small black head capsule is usually withdrawn and not visible unless the larva is feeding, and there are two dark spots on the hind end, located within fleshy, fingerlike projections. Color is variable, from gray to greenish brown. The term “leatherjacket” is often applied to this larva and those of related species. Adults somewhat resemble enormous mosquitoes but lack biting mouthparts and are harmless. Life History and Habits Winter is spent as partially grown larvae. They resume feeding in spring, during which they grow rapidly and produce most injury. During the day, feeding occurs belowground, but the larvae often migrate to feed on the surface during warm nights. They become full grown in early summer but do not pupate in soil burrows until August. Adults emerge in late August and early September. Mating occurs immediately, and most eggs are laid within one to two days of emergence. The egg-laden females cannot fly well and insert eggs into the upper layer of soil. High moisture conditions are essential for survival of eggs, which subsequently hatch in about 2 weeks. The insects grow rapidly during the fall, before slowing activity with the onset of cool weather.

504

B

C A. Carrot rust fly damage. WHITNEY CRANSHAW

B. Carrot rust fly. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Larva of a carrot rust fly. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

A

D E

D. Carrot rust fly tunneling of carrot. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F

G

H

I

E. European crane fly. WHITNEY CRANSHAW

F. Crane fly eggs. DAVID SHETLAR

G. Crane fly larva. DAVID SHETLAR

H. Larvae of a European crane fly. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

I. Pupa of a European crane fly. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

flIes assOcIated wIth the rOOt area Of turfGrass

Other Flies Associated with the Root Area of Turfgrass A second species of turfgrass-damaging crane fly native to Europe, Tipula oleracea (often called the “marsh” or “common crane fly”), has become established in parts of the Pacific Northwest and northeastern states. This species has two generations per year, with adults present in both spring and fall. In eastern North America, this species is spreading faster than the European crane fly. Damage is similar to the European crane fly. The family of crane flies (Tipulidae) is the largest of all the flies, with more than 1,500 species in North America. With the exceptions above, none of the other species are considered plant pests in any manner. Larvae develop in moist areas where moist decaying organic matter is present. Adults are sometimes known as “mosquito hawks” or are mistaken for large mosquitoes. Neither characterization is warranted, as adult crane flies do not feed and are of innocuous habit. Australian sod fly (Inopus rubriceps)2 has become established in areas of northern California, where it develops on the roots of various turfgrasses, sometimes producing extensive thinning. The adults live only about a week and most are observed in fall. Females lay their eggs in soil and the larvae may take up to two years to complete development. Larvae of march flies 3 may sometimes be observed when examining the soil around areas of dead grass in low spots, where large masses of the larvae may sometimes be seen. The larvae feed almost entirely on decaying plant but will tunnel among the roots and may do some minor root feeding. The adult stages are much more commonly observed, emerging in spring, sometimes in very large numbers. They are fairly slow moving and most feed on nectar, incidentally producing significant pollination in their flower visits. Males may produce large mating swarms that attract receptive females. Subsequently the insects are often observed as mating pairs. Females move to the soil where they lay a single mass of a couple hundred eggs and then die shortly afterward. Most North American march flies are in the genera Bibio or Dilophus. One species present in the southeastern U.S., known as the “lovebug” (Plecia nearctica), has some notoriety as they may become very abundant at times, when they are splattered in large numbers by passing vehicles. 1

Diptera: Tipulidae; 2 Diptera: Stratiomyidae; 3 Diptera: Bibionidae

506

above: Adult of the marsh crane fly. DAVID SHETLAR

below: Egg mass of a March fly. DAVID SHETLAR

A. Mating pair of crane flies. DAVID SHETLAR

B. Adult of the Australian sod fly. DAVID SHETLAR

C. Larvae of the Australian

sod fly.

DAVID SHETLAR

D. Mating pair of March flies. DAVID SHETLAR

E. March fly. DAVID SHETLAR

F. March fly larvae and pupa. DAVID SHETLAR

G. Mating pair of lovebugs. DAVID SHETLAR

A C

D E

F

G

B

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

FUNGUS GNATS (Bradysia spp.)1 hosts Fungus gnats are ubiquitous insects in yards and gardens. They are most commonly observed when developing in soil of indoor-grown plants but also occur in mulch and decaying plant material in lawns and gardens. Damage In their association with indoor grown plants, fungus gnats are considered primarily a nuisance. The small, gnatlike adults emerge from houseplant soil and may become an annoyance as some disperse into living areas and collect around windows. Large numbers of adult fungus gnats may also emerge from outdoor mulch beds. Although fungus gnat larvae develop primarily on fungi and decaying plant matter, they may also do some feeding on root hairs and on cuttings being rooted in soil. Direct damage to plants is often minor but does occur, particularly where conditions of excessive soil moisture are present. Feeding can contribute to root diseases by creating wound openings in rootlets and larvae may move pathogens in the soil. Fungus gnats are also the most important pest of mushroom houses, where they directly feed on the mushrooms. Distribution Throughout North America and common, indoors and outdoors. Bradysia coprophila and B. impatiens are two species that are particularly common with indoor-grown plants. Appearance The adults are small (up to ⅛ inch), delicate, dark flies somewhat resembling tiny mosquitoes. A single Y-shaped vein on the wings is useful for differentiating them from various other small flies. Fungus gnats are weak fliers and often run, or make short skipping flights, across soil and other surfaces. The larvae are wormlike, translucent with a dark head, and about ¼ to ⅜ inch when full grown. Life History and Habits Fungus gnats are associated with damp environments. Eggs are usually laid as clusters or strings in cracks of the soil surface. Immature stages (larvae) occur primarily within the top ½ inch of the soil and are rarely observed. Although larvae feed primarily on soil fungi, they also feed directly on root hairs and on leaves lying on the soil. Larval development typically requires 2–3 weeks to complete, and pupation occurs in the soil. The adult stage is brief, with females laying most eggs during a 3- to 5-day lifespan. Fungus gnat larvae are very common insects in lawns, where they develop on decaying plant matter. Under some conditions, including high rainfall, mass migrations of the larvae may occur, attracting considerable attention.

Other Small Flies Associated with Indoor Plant Production Very moist conditions supporting bacterial or algal growth may support other flies in greenhouses and in pots of houseplants. Shore flies (Scatella stagnalis primarily)2 are about the same size as the common fruit/vinegar fly but gray in color. The light gray wings are also marked with dark patterning. Adults and larvae feed on the bluegreen algae that form on the surface of potting mixes. They have not been associated with plant injuries but produce dark “fly specks” (regurgitation and defecation spots) that can speckle containers, plant leaves, and flowers on which the flies rest. Moth flies (Psychoda spp.)3 are small flies with hairy wings they hold over the body in a manner that gives them the appearance of a tiny moth. The larvae develop in films of bacterial scum that grow in sites that are intermittently moistened and have some nutrients. In greenhouses, areas where flowing run-off water is present may produce suitable breeding sites. Moth fly larvae may also breed in filters and drains, leading to other common names of “filter flies” and “drain flies.” Outside, large numbers of drain flies can be found where irrigation systems keep mulch constantly wet.  Diptera: Sciaridae; 2 Diptera: Ephydridae; 3 Diptera: Psychodidae

1

508

B

C D

E

A F

A. Fungus gnat. DAVID CAPPAERT, BUGWOOD.ORG

B. Fungus gnat adult on soil surface. WHITNEY CRANSHAW

C. Fungus gnat larvae.

G

DAVID CAPPAERT, BUGWOOD.ORG

D. Fungus gnat larvae

on a potato slice.

H

WHITNEY CRANSHAW

E. Fungus gnat larvae in

thatch area of a lawn. DAVID SHETLAR

F. Fungus gnat caught on sticky card. WHITNEY CRANSHAW

G. Mating pair of dark

winged fungus gnats.

JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Fungus gnat (left) and shore fly.

I

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

I. Shore flies and associated “fly specking,” WHITNEY CRANSHAW

J. Shore flies caught on sticky card.

J

JIM BAKER, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

K. Moth fly larvae. JIM KALISCH, UNIVERSITY OF NEBRASKA

L. Moth fly. DAVID SHETLAR

L

K

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

FLIES ASSOCIATED WITH DECAYING ORGANIC MATTER AND COMPOST Perhaps the best-known insect to develop in decaying organic matter is the house fly (Musca domestica),1 a common fly that regularly finds its way indoors. Moist decomposing plant materials and wet manures are the primary breeding sites for the larvae. Lesser house fly (Fannia canicularis)2 looks like a small version of the common house fly. This fly also breeds in moist decaying plant matter as well as animal manures and commonly infests compost piles that are kept too wet. The larvae of the lesser house fly are distinctive with rows of spines arising from each body segment. The adult flies have an annoying habit of hovering in numbers in shaded areas, under tree overhangs, in open walkways, and similar areas. “Fly specks” defecated by adults of both house flies and little house flies will often conspicuously mark surfaces on which they rest. Black soldier fly (Hermetia illucens),3 a medium-sized fly ⅝ to ¾ inch long, is slender and resembles a black bee or wasp. Females have two light spots at the base of the abdomen and males often reflect bronze in bright light. The larvae appear as armor-plated maggots that feed on decaying organic matter, especially decaying plant material, but black soldier fly is notorious for breeding in outdoor latrines and moist piles of poultry manure. This fly is actually sold as an aid to assist in breaking down compost piles that are not allowed to reach high temperatures. The adult flies commonly dart back and forth over or near decaying plant heaps, where they often display to each other by waving their front legs. The adults also frequent nearby flowers where they feed on nectar. This fly can also inhabit vermicompost piles. Phorid (humpbacked) flies (usually Megaselia scalaris4) are the same size and color as the common fruit (vinegar) flies with which they are commonly confused. Phorid flies have a distinctively humped thorax and Life stages of the house fly. they tend to run and fly in a darting manner, lending them another common CLEMSON UNIVERSITY–USDA COOPERATIVE name, “scuttle fly.” The larvae feed on a wide range of wet, decaying organic EXTENSION SLIDE SERIES, BUGWOOD.ORG matter, but they are very capable of feeding on decaying fats, carrion, and wet feces. The larvae are typical white to cream-colored maggots, and the puparia are light brown with two distinctive horns arising from the tail end. While phorid flies can breed in wet garbage and feces, they can also be attracted to compost piles that are kept too wet and not allowed to reach high decomposition temperatures. Vinegar (small fruit) flies (usually Drosophila spp.)5 occasionally occur where moist organic matter, such as overripe fruit or discarded vegetable matter, has begun to ferment. Adults are highly attracted to odors produced by fermentation and the larvae feed on yeasts. Vinegar flies are discussed in more detail in chapter 7. Dung flies 6 are small to medium-sized flies that are typically yellow to brown and very hairy. As their common name implies, many species have larvae that feed on fresh animal dung, so the adults are commonly seen around pastures. However, several species have larvae that feed on any kind of decaying plant matter, including overly moist compost piles. The larvae are typical white to cream-colored maggots. Adults of some species feed on small insects and are considered beneficial predators. 1

Diptera: Muscidae; 2 Diptera: Fanniidae; 3 Diptera: Stratiomyiidae;

4

Diptera: Phoridae; 5 Diptera: Drosophilidae; 6 Diptera: Scathophagidae

510

A. Little house fly. DAVID SHETLAR

B. Larvae of the little house fly. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Black soldier fly.

A

WHITNEY CRANSHAW

B C

D. Larvae of the black soldier fly. WHITNEY CRANSHAW

E. Phorid fly adult. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Vinegar fly. WHITNEY CRANSHAW

G. Vinegar fly larvae developing

in overripe banana. WHITNEY CRANSHAW

H. Yellow dung flies. WHITNEY CRANSHAW

I. Dung fly. WHITNEY CRANSHAW

D

E

G H

I

F

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

MOLE CRICKETS Unlike most members of the order Orthoptera, it is the forelegs rather than the hind legs that are highly developed in mole crickets. This adaptation allows them to dig, and the great majority of mole cricket life history occurs belowground. Mole crickets are a small family, with three native North American species and four introduced species, three of which are important pests in parts of the southern U.S.

Tawny Mole Cricket (Scapteriscus vicinus)1 hosts Warm-season turfgrasses, particularly bermudagrass, St. Augustinegrass, and bahiagrass. Tawny mole cricket occasionally damages roots of vegetables and ornamentals. Damage Tawny mole cricket feeds on roots of grasses and causes serious pruning. Much damage also results incidentally from the physical effects of its tunneling, which can dislodge plants and cause roots to dry. This occurs most commonly in late summer when larger nymphs are most active. Distribution Southeastern U.S. into eastern Texas. Within this region it is most common in sandy soils. Appearance Mole crickets are cylindrical in body form and about 1–1¼ inches long when full grown. Most are tan to golden brown with the area behind the head mottled. The prothorax is greatly extended, and the front legs are thickened and enlarged for digging. The hindwings of the adult extend shortly beyond the tip of the abdomen. Life History and Habits Most tawny mole crickets winter as adults. Mating occurs in spring, after which the females begin to excavate small chambers in the soil for egg laying. Eggs are laid in groups and hatch in about 10 days. The nymphs subsequently leave the egg chamber and move to the surface to feed on plant matter, including roots, and small insects. Most feeding occurs at night, with retreat to a burrow during the day. One generation is produced annually. Adult mole crickets are capable of flight. Mating and dispersal flights are most common on warm spring nights, and the adults are strongly attracted to lights. Smaller flights may occur in the fall. During the mating period, mounds of soil may be thrown up around burrow entrances where males chirp.

Other Crickets Associated with Soil Southern mole cricket (Scapteriscus borellii)1 is also very damaging to turfgrasses in the southern coastal states from North Carolina to Texas. This species has also been introduced into southern Arizona. It is primarily carnivorous, however, and damage results almost entirely from the effects of burrowing. The primary overwintering stage is a nearly full-grown nymph. Southern mole cricket is slightly more slender than tawny mole cricket and is grayish to reddish brown. It is quite an active insect, though it may readily play dead when disturbed. Shortwinged mole cricket (S. abbreviatus) presently occurs in Florida with a small disjunct population in Georgia. It damages turfgrasses in a manner similar to tawny mole cricket. The wing covers of the adults do not extend beyond the abdomen in this species.

512

A B

D

F

C

E

A. Life stages of the tawny mole cricket. DAVID SHETLAR

B. Male tawny mole cricket. DAVID SHETLAR

C. Tunneling produced by tawny mole cricket. DAVID SHETLAR

D. Burrows produced by tawny mole cricket. DAVID SHETLAR

E. Shortwinged mole cricket. DAVID SHETLAR

F. Southern mole cricket, male and female. DAVID SHETLAR

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

crIcKets assOcIated wIth sOIl Native mole cricket (Neocurtilla hexadactyla)1 generally occurs east of the Rocky Mountains from southern Canada through the Gulf States. It is primarily a predator of other insects and not normally associated with plant damage; however, it is an occasional curiosity found in yards and gardens. In some southern zones, the common short-tailed cricket (Anurogryllus arboreus)2 can be found constructing burrows in turf or garden soils. This species often occurs in colonies of several dozen individuals in an area. The cricket looks much like the brown house cricket, but the wings are short and females lack a needleshaped ovipositor. The crickets make base burrows that often extend a foot or more into the soil. They don’t normally feed on plant roots, but they constantly kick out soil in little mounds. They usually emerge at night to feed on aboveground plant parts. Jerusalem crickets (Stenopelmatus fuscus and many other species)3 are relatively uncommon insects in yards and gardens, but they have a bizarre appearance that attracts attention when encountered. They are fairly large, typically 1–2 inches, generally shaded brown or gray, and have an enormous head. Various local names are given, including “children of the earth” and “potato bugs.” Jerusalem crickets occur primarily west of the Rocky Mountains and are most abundant along the Pacific Coast, from British Columbia into Mexico. It is presently estimated that close to 40 species of Jerusalem crickets occur in western North America. Jerusalem crickets have stout legs adapted for digging. They can burrow deeply into moist light soils and may also rest in soil cracks and under rocks or boards. They are active at night and are omnivores that feed on a wide variety of foods, including insects as well as plant matter. They have been reported to occasionally damage roots and tubers of plants, but their importance as plant pests is minor. Jerusalem crickets can bite if handled carelessly, giving a fair pinch, but normally will attempt to flee and avoid contact. Both adult and immature (nymph) stages will survive through winter, remaining dormant in soil burrows. Jerusalem crickets have a prolonged life cycle and take about 4–5 years to mature.  Orthoptera: Gryllotalpidae; 2 Orthoptera: Gryllidae (Brachytrupinae);

1 3

Orthoptera: Stenopelmatidae (or subfamily Stenopelmatinae of the Gryllacrididae)

514

A

B

C D

A. Native mole cricket. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Common short-tailed cricket. DAVID SHETLAR

C. Short-tailed cricket mounds. DAVID SHETLAR

D. Nymph of a common short-tailed cricket. DAVID SHETLAR

E. Jerusalem cricket. WHITNEY CRANSHAW

F. Jerusalem cricket. JIM KALISCH, UNIVERSITY OF NEBRASKA

E

F

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

SUBTERRANEAN TERMITES Termites1 are well known for their ability to use the cellulose of wood as a food source. Because of this, these insects can seriously damage wood and related materials, causing billions of dollars of damage annually in North America alone. Direct injury to living plants is uncommon but does occur, particularly in dry soils. In addition, gardeners may encounter termites about the yard, associated with garden structures, woodpiles, and other sources where wood is in direct contact with the ground. All termites are social insects that live in a colony containing hundreds to thousands of individuals of various specialized function (castes): workers, soldiers, and reproductive forms, the last of which are often winged. Colonies are usually initiated by a fertile female (queen) and male (king) that pair after dispersal from their home colony in the course of a mating flight. After pairing, they drop their wings and use their flight muscles for energy during colony initiation. Colony growth is slow during the first year or so but may increase rapidly once the colony is established. Cellulose is the basic material in the diet, and termites are essentially the only insects that can use this extremely common material, which makes up the cell walls of plants. This is possible because of mutualistic microorganisms that establish in the digestive tract (protozoans and bacteria) of termites. These microbes, found nowhere else in nature, digest the cellulose and produce nutrients that can become usable to termites. Most termites that cause serious damage in the U.S. are in the family Rhinotermitidae,1 the subterranean termites. These termites maintain colonies in the soil but can forage aboveground to obtain cellulose. The most widespread and commonly encountered termites are in the genus Reticulitermes. Six Reticulitermes species occur in North America, of which eastern subterranean termite (R. flavipes), western subterranean termite (R. hesperus), southeastern subterranean termite (R. virginicus), and arid-land subterranean termite (R. tibialis) are most damaging, probably in that order. Established Reticulitermes colonies typically include 60,000–200,000 or more individuals that may forage over an area of about ⅓ acre. Large colonies often develop secondary reproductives that don’t form wings but are capable of mating and producing eggs. Damage to plants by subterranean termites is infrequent. They have been known to tunnel plant roots and stems, particularly when soils become very dry. They may also invade the heartwood of trees, primarily dead wood in tree trunks, and contribute to structural weakening. Formosan subterranean termite (Coptotermes formosanus)1 is a far more aggressively damaging species. It may nest in soil but can also make aboveground “carton” nests of mixed saliva, excrement, and soil. The nests may be located in buildings behind walls or under roofs but are also common in trees. In addition to causing extensive damage to buildings, this species also damages trees. More than 20 species of trees have been attacked in the New Orleans area alone, including oak, cypress, pine, elm, and maple. Formosan termite colonies can become extremely large and include more than 7 million individuals. Typically about 10–15% are soldiers that can secrete a gluey defensive fluid from the head. As many as 70,000 winged reproductives have been recorded to emerge from a single colony during swarming flights, which take place in evenings in May and June. Winged stages are yellowish brown and ½ inch, larger than Reticulitermes. Formosan subterranean termite is currently established in most of the Gulf States and in parts of Georgia and South Carolina. A spot infestation is present in southern California, and the species has long been established in Hawaii. Where established, it has often displaced other subterranean termite species.  Blattodea: Rhinotermitidae

1

516

A

B

D

E C F

G H

A. Workers and soldiers of the eastern subterranean termite. DAVID SHETLAR

B. Soldier of an eastern subterranean termite. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Tunneling of a tree stump

by subterranean termites. DAVID SHETLAR

D. Tunneling of a piece of

I

building lumber by eastern subterranean termite. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Subterranean termite queen

with attendant king and workers. DAVID SHETLAR

F. Winged reproductive forms

of eastern subterranean termite.

J

GARY ALPERT, HARVARD UNIVERSITY, BUGWOOD.ORG

G. Mud tubes of an eastern

subterranean termite on fence post. TERRY S. PRICE, GEORGIA FORESTRY COMMISSION, BUGWOOD.ORG

H. Exposed mud tube produced by subterranean termites. JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Carton nest of Formosan termite. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

K

L

J. Workers and soldiers

of Formosan termite.

SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

K. Workers of Formosan termite

sealing breech in colony wall. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

L. Winged reproductive

forms of Formosan termite. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

ANTS Ants are among the most commonly encountered insects in any yard and garden. All the nearly 700 North American species are social insects that live in colonies consisting of female workers, one or more queens, and the brood (eggs, larvae and pupae). Mature colonies may produce reproductive forms that include winged males and females (potential queens) that leave the colony during mating flights. Ants have a fantastic range of habits, and their effects on gardens can be highly variable. Most ants feed on other insects as part of their diet, and some are highly beneficial predators of plant pests. Many ants also use sugary materials as an important part of their diet. This sugary material often includes the honeydew excreted by many Hemiptera that feed on the fluids of plant phloem (e.g., aphids, soft scales, whiteflies, mealybugs, leafhoppers, and treehoppers). Mutualistic associations can develop between certain ants and honeydew-producing insects in which the ants “tend” and protect the insects from which they derive food. When this tending occurs, ants may seriously disrupt the activities of natural enemies such as lady beetles, lacewings, and other biological control agents, indirectly contributing to plant problems. A few ants directly damage plants. Some feed on seeds or soft plant tissue, especially the harvester ants. Colonies of Texas leafcutting ant (page 168) occasionally defoliate shrubs and returning the fragments of cut leaves to the colony, where they are used to culture special fungi that serve as the primary food source of this ant. Some ants damage plants by extensive tunneling around the root system, excavating trunks for nesting, or killing tissues with toxic secretions such as formic acid. Finally, some ants, notably the red imported fire ant, can cause produce painful stings.

Red Imported Fire Ant (Solenopsis invicta)1 Damage Fire ants are primarily predators of other insects and can be effective at controlling a wide range of plant pests. However, they occasionally directly damage plants by feeding on seedlings and the tender growth of many garden plants. Buds, pods, and fruits may occasionally be damaged, with okra particularly susceptible to injury. Fire ants may tunnel tubers and their soil tunneling can disrupt the root system of plants, including citrus. Red imported fire ants aggressively defend nests and produce a painful sting. Small whitish pustules typically develop at sting sites. Sensitivity to fire ant stings varies greatly and serious, medically-important reactions occur with some individuals. Distribution From its original introduction in Mobile, Alabama, red imported fire ant has spread to currently infest some 260 million acres throughout eleven southeastern states, extending to the eastern two-thirds of Texas. Since the late 1990s it has been found in parts of New Mexico, Arizona, and California. Appearance The red imported fire ant is reddish brown and quite small, with individuals ranging in size from 1 ⁄16 to ¼ inch. Life History and Habits Colonies are initiated by a single fertilized female (queen) shortly after the mating flight. She soon pulls off her wings, then uses her flight muscle tissues to sustain her during colony establishment. The immature stages of development all take place in the nest and require about 2–3 weeks following egg hatch to complete. Colony size grows rapidly as new workers take over the chores of colony maintenance and foraging. Individual workers typically live for about 5 weeks after reaching the adult stage, but queens typically live 2–6 years. Winged reproductive forms (males and reproductive females) begin to be produced after a year or so and permanently leave the colony during mating flights. Mating flights usually take place in the afternoon following rains. 518

A

B C D

A. Red imported fire ants. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

B. Nests of red imported fire ant built next to electrical boxes. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Mound of red

imported fire ant. DAVID SHETLAR

D. Red imported

E

F

fire ant stinging. DAVID SHETLAR

E. Skin reaction

to stings of red imported fire ant. DAVID SHETLAR

F. Red imported fire

ants foraging along swimming pool. DAVID SHETLAR

G. Red imported

fire ants preying on beetle larvae.

HERBERT A. “JOE” PASE III, TEXAS A&M FOREST SERVICE, BUGWOOD.ORG

G

H. Winged female of red imported fire ant. JOHNNY N. DELL, BUGWOOD.ORG

H

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

ants

Red Imported Fire Ant continued Some colonies have multiple queens. When this occurs, colonies may also be established by “budding,” with individual queens moving with part of the colony to a new location. Single-queen colonies may also readily move, as a single intact colony, to a new location if conditions become unfavorable at the original nest site. Red imported fire ants feed on a wide variety of materials. Mostly they eat living or dead insects, earthworms, or other materials of animal origin. Workers also collect honeydew and forage for sweets, proteins, and fats from various sources. Plant feeding is infrequent. Related Species Black imported fire ant (Solenopsis richteri)1 is another introduced species of fire ant, native to South America, that can also be an important stinging species. It is thought to be a bit less tolerant of cold temperatures than the red imported fire ant and is presently known to occur in parts of Alabama, Mississippi, Southern fire ants preying Georgia, and Tennessee, with a spot infestation in the Tidewater area on forage looper. WHITNEY CRANSHAW of Virginia. Apparent hybrids of this species with red imported fire ant occur in some parts of this region. In addition, Solenopsis species native to North America are present in the southern U.S. Among these the southern fire ant (S. xyloni) has the widest distribution, occurring across the southern U.S. from Georgia to California. They are scavengers and predators that feed primarily on oily and fatty meats and seeds as well as carrion and insects. Although capable of producing a painful sting, the native species of fire ants are much less frequently encountered by humans than the introduced species, and stings are rare.

Other Ants Common in Yards and Gardens

Field ants tending aphids. JIM KALISCH, UNIVERSITY OF NEBRASKA

Field ants (Formica spp.)1 are common throughout North America. Most are black, but many are reddish brown or of variable color. They are moderately large and sometimes mistaken for carpenter ants but can be distinguished by the indentation on the back of the thorax. Field ants nest in soil, sometimes creating large mounds mixed with plant debris. When nesting they often clear the area around the nest and may damage adjacent woody plants by secreting formic acid that damages tender bark. Field ants actively seek sweets and readily tend aphids and soft scales for their honeydew. They also feed on insects and can be important predators. Pavement ant (Tetramorium caespitum)1 is an introduced species currently found in much of the northern half of the U.S. and southern Canada with a steadily expanding range. It attracts attention by the piles of fine soil and sand it commonly produces in sidewalk cracks, among patio stones, and near the base of buildings. On sunny afternoons following some rainfall, large numbers of winged reproductive stages may be pushed out of the nests for mating flights. Adjacent colonies of pavement ants may briefly fight for territory with thousands of ants covering several square feet of pavement. These battles rarely last for more than a few hours. Pavement ants are generalists in their feeding habits, feeding on living and dead insects, pollen, honeydew, and small seeds. 520

A C D

F

B E

G

A. Black imported fire ant. NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

B. Southern fire ant. JACK KELLY CLARK, COURTESY OF =UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Field ants collecting nectar

H

from tumpetvine flower. DAVID SHETLAR

D. Field ant mound. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Field ants tending aphids.

I

DAVID SHETLAR

F. Pavement ant workers. JOSEPH BERGER, BUGWOOD.ORG

G. Mounds produced

by pavement ants. WHITNEY CRANSHAW

H. Pavement ants battling

at nest entrance.

JIM KALISCH, UNIVERSITY OF NEBRASKA

J

I. Pavement ants feeding

on dead camel cricket.

JIM KALISCH, UNIVERSITY OF NEBRASKA

J. Paired pavement ants

during battle. DAVID SHETLAR

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

ants Argentine ant (Linepithema humile)1 is now found throughout most of the southern states, in California, and in isolated infestations in many other areas. It can become a serious household pest, readily nesting around the base of homes and commonly foraging indoors, particularly when the weather is cool and wet. It is highly aggressive to other surface-foraging ants and commonly displaces native species, resulting in some severe ecological impacts, particularly seed dispersal. In gardens, Argentine ant is often important as it tends and protects aphids, whiteflies, soft scales, and other honeydew-producing insects from natural enemies. Nests may honeycomb the soil around the base of aphid-infested plants, further stressing plants by exposing roots. Argentine ant is a relatively small ant, with workers about 1⁄10 inch and light to shiny dark brown in color. Odorous house ant (Tapinoma sessile)1 is a fairly small (⅛ inch) dark brown ant that gets its name from its ability to produce an odor, sometimes described as similar to rotten coconuts, when disturbed. They nest in soil, particularly at sites with mulch or other covering debris. They feed primarily on sugary materials and readily tend honeydew-producing insects. During the warm months, colonies often spread widely, establishing temporary satellite colonies near new areas of foods, but these tend to retreat back to the main nest during winter. Odorous house ants are among the common ants that enter homes, and they sometimes establish temporary nests in cavities around flooring or other suitably moist, warm sites in buildings. An increased incidence of odorous house ants as nuisance invaders of homes has been reported from many areas; this increase is often speculated to be associated with increased use of mulch around building foundations. Several Lasius species1 of ants can be common in yards and gardens. Among the more common species are the cornfield ant (Lasius alienus), L. neoniger, and L. pallitarsus. These are light brown ants, about ⅛ inch long. Lasius neoniger may also be noted in turfgrass sites that are open and have sandy soils, where the ants may conspicuously pile soil at the burrow entrance. Some species, known as “citronella ants,” can produce a strong citronella or lemon verbena odor. Common species of citronella ants include L. interjectus (larger yellow ant) and L. claviger (smaller yellow ant). Lasius species feed primarily on sugary materials and develop associations with honeydew-producing insects, both above- and belowground. Best known and among the more developed of these is the mutualistic relationship between the cornfield ant and the corn root aphid (Protaphis middletoni). Eggs of the corn root aphid are collected by the cornfield ant in autumn, stored, and then moved in spring to roots of plants on which the aphids can then develop. Most associations between these ants and honeydew-producing insects are more casual, with the ants collecting honeydew and providing some protection from predators, in the manner of many other ants (e.g., field ants, Argentine ant, odorous house ant). Carpenter ants (Camponotus spp.)1 are particularly common in wooded areas and is a diverse genus, with 48 North American species. They are among the largest of all North American ants, but size of workers in individual colonies is highly variable. Black carpenter ant (C. pennsylvanicus), common in much of the eastern U.S., is black, as are many other carpenter ants. (Other black species of carpenter ants that commonly damage wood include C. modoc in the western states and C. herculeanus throughout the northern U.S. and southern Canada.) Other carpenter ants may be partially or almost completely reddish brown, such as red carpenter ant (C. novaboracensis), common in the upper Midwest and southern Canada, and Florida carpenter ant (C. floridanus), a bicolored species found in the southeastern states. The thorax of all carpenter ants in side view is broadly and smoothly arched, a diagnostic characteristic that allows these ants to be separated from other large ants such as field ants.

522

B

C

D

E

A F

G

A. Argentine ants tending soft scales. WHITNEY CRANSHAW

B. Argentine ants visiting sweet bait. WHITNEY CRANSHAW

C. Odorous house ants

carrying larvae. DAVID SHETLAR

H

I

D. Nest of Lasius species ants

with root aphids. DAVID SHETLAR

E. Winged reproductive stages of a

Lasius species during mating swarm. DAVID SHETLAR

F. Workers and winged reproductive

forms of carpenter ant.

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Carpenter ants tending eggs. JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Sawdust expelled from nest entrance of carpenter ants in landscape timber.

J

K

EDWARD H. HOLSTEN, USDA FOREST SERVICE, BUGWOOD.ORG

I. Dead tree used for nesting by carpenter ants. STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

J. Carpenter ant collecting sweet

ooze from peony bud. DAVID SHETLAR

K. Winged male and female

carpenter ant. DAVID SHETLAR

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

ants Carpenter ants nest in wood, excavating an extensive system of tunnels that become smoothly polished. Shredded wood fragments are expelled from the openings. Initial nesting is confined to wood that is partially decayed, but as colonies expand they may enter sound wood of tree trunks. Structural weakening of old trees and occasional infestations of timbers in homes are the primary concerns with carpenter ants. Carpenter ants can produce a mildly painful bite but do not sting. Their diet is mixed and includes living and dead insects as well as honeydew. Protein-rich foods tend to be favored early in the season, with more sweets taken later. The black carpenter ant often establishes satellite colonies (only workers, larvae, and pupae are present) in wall voids of buildings, and the southern species of carpenter ants can set up satellite colonies in outdoor switch boxes and irrigation maintenance boxes. Ants in the genus Crematogaster1 are small black ants that are distinctive in having an abdomen that is heart-shaped and pointed. Common names include “acrobat ants” or “cocktail ants,” the latter referring to their habit of raising the abdomen (“cocking” the “tail”). Most nest aboveground, in small hollows of trees and shrubs. In gardens they are most often seen collecting honeydew from aphids and soft scales. Harvester ants (Pogonomyrmex spp.)1 are native to much of western North America and build large, low mounds. They are common in grasslands and rarely establish around a garden but clear an area of vegetation around the mound. Harvester ants are seed feeders. Although capable of producing painful stings, they are not aggressive and rarely sting unless their colony is directly disturbed. European fire ant (Myrmica rubra)1 is an introduced species presently known from a few areas of the northeastern U.S. and eastern Canada. Populations can build up to high levels, particularly in coastal areas and along streams and rivers. Nests are not obvious, as they are hidden among the vegetation in moist spots, and the European fire ant can produce a painful sting. This ant has not been observed to produce winged reproductive stages in North America, so long-distance dispersal to new areas is through human-assisted transfer of infested soil.

top: Small above ground nest in tree produced by acrobat ants. DAVID SHETLAR

above: Harvester ant carrying seed.

 Hymenoptera: Formicidae

1

WHITNEY CRANSHAW

524

A

B

C D

E

F

G

A. Acrobat ants tending soft scales for honeydew.

E. Harvester ant

collecting seed.

DAVID SHETLAR.

WHITNEY CRANSHAW

B. Acrobat ant nest

F. Mating balls of

with larvae.

harvester ants.

WHITNEY CRANSHAW

WHITNEY CRANSHAW

C. Harvester ant mound.

G. European fire ant.

WHITNEY CRANSHAW

GARY ALPERT, HARVARD UNIVERSITY, BUGWOOD.ORG

D. Harvester ants at nest entrance. WHITNEY CRANSHAW

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

ROOT APHIDS AND OTHER SUCKING INSECTS Various Pemphigus species1 of aphids, sometimes known as petiolegall aphids, are root feeders during part of their life cycle. These winter as eggs on twigs of poplar and cottonwood and produce swellings on leaves, petioles, and stems of these plants in spring (page 322). Winged stages fly from these winter hosts to feed on the roots of various plants during the summer, crawling to the roots via soil cracks. Sugarbeet root aphid (P. populivenae) is widespread in much of North America and produces colonies on the roots of lambsquarter, beet, quinoa, and related plants in the summer. Severe wilting of sugarbeet occurs on susceptible varieties in the Dakotas and western states. Lettuce root aphid (P. bursarius) is sometimes important in California lettuce production. Both these species have a fairly wide host range that includes several plants in the aster and beet families. Winged forms disperse from the summer hosts to seek their cottonwood/poplar winter hosts in late summer. Pemphigus populitransversus develops on the roots of crucifers; the alternate stages produce petiole galls on cottonwood. Several species of Eriosoma1 use elm as a primary overwintering host but feed on roots of alternate hosts in summer. Woolly elm aphid (E. americanum) can be found on the roots of Amelanchier in the summer and has been associated with serious production losses in nurseries located near elms that support the winter generation. Woolly apple aphid (E. lanigerum) is observed mostly on the aboveground stems and suckers of apple and crabapple, but can colonize the roots. In warmer areas this insect may persist overwinter on roots of these Malus spp. hosts and can produce large knotlike swellings of the roots, typically also associated with fungal pathogens. Many other aphids develop on roots and do not have an alternate woody plant winter host. Western aster root aphid (Aphis armoraciae)1 occurs on roots of aster, dandelion, chicory, sunflower, horseradish, Artemisia and Asclepias species, and dock. Corn root aphid (Protaphis middletoni),1 also known as the erigeron root aphid, is sometimes a pest of aster and cornflower. Tulip bulb aphid (Dysaphis tulipae)1 is a common species found among the bulbs, roots, and stem bases of gladiolus, tulip, iris, carrot, celery, and waterhemlock.

Serviceberry plants damaged by root forms of the woolly elm aphid. WHITNEY CRANSHAW

526

A

B

C D

F

G

E

H

A. Lettuce root aphids. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

B. Petiole gall on Lombardy pople produced by the lettuce root aphid. WHITNEY CRANSHAW

C. Sugarbeet root aphids on garden beet.

I

WHITNEY CRANSHAW

D. Root forms of the poplar petiolegall

aphid on cabbage roots.

ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD

E. Petiolegall on cottonwood produced

by the poplar petiolegall aphid. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Woolly elm aphid colony on the roots of serviceberry. WHITNEY CRANSHAW

G. Tulip bulb aphids. WHITNEY CRANSHAW

H. Galled apple root damage produced

by woolly apple aphid.

UNIVERSITY OF GEORGIA PLANT PATHOLOGY, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

I. Western aster root aphids on dandelion root. WHITNEY CRANSHAW

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

rOOt aPhIds and Other sucKInG Insects Forda marginata1 and F. formicaria develop on roots of various grasses including Kentucky bluegrass. The rice root aphid (Rhopalosiphum rufioabdominalis)1 feeds on the roots of a wide variety of plants, particularly grasses, and is well adapted to living in very wet sites. It is commonly encountered in hydroponic production of many types of plants, including cannabis. Soil-dwelling stages of the grape phylloxera (Daktulosphaira vitifoliae)2 can severely damage roots of European grape (Vitis vinifera). They are generally oval in body form and range in color from yellow to olive green or orange-brown. Areas around feeding sites are often killed, and damage to rootlets produces stunting and clublike growths. Aboveground symptoms appear as progressive decline of vines and production, often leading to death of the plant. Grape phylloxera is native to eastern North America, where it is associated with Vitis riparia and V. labrusca. These species are resistant to root injuries by grape phylloxera, producing a defensive response that kills or severely limits root-feeding stages. On these species (but not V. vinifera) they produce leaf galls (page 324). Mealybugs3 that develop on roots include several Rhizoecus species. Ground mealybug (R. falcifer) develops on roots of many ornamental plants, including anemone, chrysanthemum, gladiolus, and iris. It is about 1⁄10 to ⅛ inch long and has a fairly rounded and smooth body covered with a fine web of slightly bluish wax. Pritchard Forda species aphids on roots of turfgrass. ground mealybug (R. pritchardii) is an important pest of DAVID SHETLAR. African violet but also develops on roots of yarrow, manzanita, avens, and milkwort. High populations of either of these insects can cause wilting and decline of infested plants. Ground pearls (Margarodes meriodionalis, Eumargarodes laingi)4 are unusual scale insects that develop on the roots of centipedegrass, bermudagrass, zoysiagrass, and St. Augustinegrass. The ground pearls develop a globular shell, known as a cyst. This covering is about 1⁄12 inch in diameter, hard and yellowish purple, and attached to the roots, sometimes as deeply as 10 inches. In spring the adults emerge from the cyst and move to the surface, where mating occurs. The female then lays small clusters of eggs shallowly in soil among the roots. The young scales move to feeding sites and begin to secrete the covering after they settle. Ground pearls occur throughout much of the southern U.S. and are particularly abundant in the southeastern and southwestern states. Severely infested grasses appear drought stressed, yellow, and may die.  Hemiptera: Aphididae; 2 Hemiptera: Phylloxeridae;

1

Leaf gall produced by the foliar form of the grape phylloxera.

 Hemiptera: Pseudococcidae; 4 Hemiptera: Margarodidae

3

WHITNEY CRANSHAW

528

A

B A. Rice root aphids at base of plant.

C D

WHITNEY CRANSHAW

B. Rice root aphids growing

on roots in hydroponic system. WHITNEY CRANSHAW

C. Colony of rice root aphids

in soil of rice plant.

EMILY LUNA, COLORADO STATE UNIVERSITY

D. Clubbed grape root produced by feeding injuries of grape phylloxera.

E

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

E. Grape phylloxera on roots

of grape.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

F. A Rhizoecus species of root-feeding mealybug. US NATIONAL COLLECTION OF SCALE INSECTS PHOTOGRAPHS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

G. Ground pearls. DAVID SHETLAR

H. Ground pearl female. DAVID SHETLAR

F

G

H

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

SOWBUGS AND PILLBUGS Some of the few crustaceans (subphylum Crustacea, class Malacostraca) adapted to life on land are those of the order Isopoda. Common species of isopods found in gardens include the pillbug (Armadillium vulgare),1 also known as the “roly-poly,” “potato bug,” or “armadillo bug,” and the sowbugs (Porcellio scaber,2 P. laevis,2 Onciscus asellus,3 Trachelipus rathkii,4 others). Distant relatives of more familiar (and sometimes culinary) animals such as lobster, shrimp, and crab, the terrestrial isopods share certain features with all crustaceans, including two pairs of antennae (the second pair is reduced), and the acquisition of oxygen through gills, rather than spiracles. The sowbugs and pillbugs have seven pairs of legs, and sowbugs possess a pair of tail-like appendages (uropods) that visibly extend from the hind end. These appendages are not visible with the pillbug, and the pillbug is also able to roll into a ball when disturbed, two features that allow one to easily distinguish sowbugs from the pillbug. All the isopods commonly found in gardens of North America are introduced species of European origin but many have since become very widely distributed. The pillbug and sowbugs usually feed at night, spending the day under cover. They can be seen during the day, however, particularly after rains or during overcast conditions. They are general scavengers feeding primarily on a wide variety of soft, partially decayed, plant matter. They possess relatively weak chewing mouthparts which restrict feeding and can do little damage to intact, healthy plant tissue. However, they are often found in association with plant tissues previously damaged by rots and may extend existing areas of damage. Sowbugs and pillbug are rather slow growing. Females will produce a number of eggs that are then carried in a special pouch on the abdomen, known as a marsupium. About two dozen eggs are deposited at a time. After the eggs hatch, the young remain within the marsupium for an extended period before ultimately leaving to forage on their own. Females carry the eggs and young for about 6–7 weeks. The general appearance of the isopod, plus the continued care of the young, is reminiscent of a pig with her litter, hence the name “sowbug.” Often two broods of eggs are produced annually. The young pillbugs and sowbugs molt for the first time within 24 hours after leaving the marsupium. Their molting process is unusual in that it occurs in two parts. The front half is shed first, followed 2–3 days later by the rear half. As they develop, molting occurs fairly regularly at approximate 2-week intervals for the first 4–5 months. After this time, molting becomes an irregular event with adults continuing to molt (unlike insects). Pillbugs and sowbugs are relatively long-lived, often surviving 2 or 3 years. 1

Isoopoda: Armadillididae; 2 Isopoda: Porcellionidae, 3 Isopoda: Oniscidae, 4 Isopoda: Trachelipodidae

OTHER LAND-ADAPTED CRUSTACEANS Crayfish (crawdads, mudbugs) are not true terrestrial crustaceans as they must maintain contact with water in order for their gills to function properly. However, several species have a semiterrestrial habit whereby they construct burrows in the soil that extend from the water table to the soil surface. In eastern North America from Canada to Texas, the digger or chimney crayfish (Fallicrambus fodiens) is the most commonly encountered semiterrestrial species. This species digs extensively in clay soils, where it can construct burrows more than 10 foot deep and with up to 4 openings at the surface. They often live in communities adjacent to wetlands, in and alongside road ditches, and in similar places where clay soils have relatively high water tables. Females keep eggs under their 530

B

C

A

D A. A pillbug, Armadillium vulgare. WHITNEY CRANSHAW

B. A sowbug, Oniscus asellus,

E F

in process of molting. TOM MURRAY

C. A sowbug, Procellio scaber. TOM MURRAY

D. Pillbugs rolled into defensive ball. WHITNEY CRANSHAW

E. Underside of a pillbug. WHITNEY CRANSHAW

F. Mud tube produced by crayfish. DAVID SHETLAR

tails during the summer months, and newly hatched young often work their way to ponds or streams for a year before they begin their burrowing habits. The normal life span appears to be 3 years. Adults place excavated mud around the surface openings, which results in “chimneys” that can extend up past the surrounding vegetation. When these clay structures dry, they can become very hard and dangerous to mowing equipment. Other species of crayfish with similar habits are devil crayfish, Lacunicambarus diogenes, found across North America east of the Rocky Mountains; and prairie crayfish, Procambarus gracilis, found from Indiana to Minnesota and down to Texas. 531

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

land-adaPted crustaceans, and MIllIPedes Amphipods (side-swimmers, scuds) are small shrimplike crustaceans that are laterally compressed. Most occur in water, and one species, Hyella azteca,2 is likely present in almost any water garden feature; however, few amphipods have adapted to life on land, and those that do occur are restricted to wet environments. Some of these can usually be seen when visiting seashores, where these “sand” or “beach fleas” are usually present under seaweed and other debris along shorelines. A much smaller number occur inland, but a few introduced species are present in yards and gardens in areas of Florida and southern California, where they are often described as “lawn shrimp.” These terrestrial amphipods live in mulch, piles of matted leaves, and under shrubbery, where they feed as scavengers on decaying plant matter. They normally attract attention only when large numbers migrate from these areas after saturating rains at which time they enter garages and homes or become trapped in swimming pools. The primary species found in North America with this habit of occasionally entering buildings include Arcitalitrus sylvaticus,3 Talitroides topitotum,3 and T. allaudi. The latter is the smallest, about 1⁄7 inch long. Arcitalitrus sylvaticus and T. topitotum are about ¼ to ⅓ inch long. 1

Decapoda: Crambaridae; 2Amphipoda: Dogielinotidae; 3Amphipoda: Talitridae

MILLIPEDES Millipedes (class Diplopoda) are most readily distinguished from other types of arthropods by having two pairs of legs on each segment of the body. Their large number of legs and body form can resemble that of centipedes (class Chilopoda), and both centipedes and millipedes can co-occur in yards and gardens under rocks or boards, around compost piles, and in other dark, moist sites. However, habits of these two types of arthropods are very different, as centipedes are predators; they are discussed on page 652. Usually the species most commonly encountered in yards and gardens are some species of julid millipede (order Julida1). These are dark brown with an elongate, round, wormlike body comprising dozens of segments. Older individuals may possess hundreds of legs, but these are small and inconspicuously held under the body. Among the common julid millipedes are various introduced species in the genera Brachyiulus,1 Ophyiulus,1 Cylindroiulus,1 and Blaniulus.1 Also common can be polydesmid millipedes (order Polydesmida2) that have a more flattened body form, with a maximum of about 20 segments, and legs that fairly prominently extend along the sides of the body. Various Polydesmus2 species and the introduced greenhouse millipede (Oxidus gracilis)2 are the types of polydesmid millipedes most often encountered. Millipedes are scavengers that feed by chewing; however, their mouthparts are small and weakly muscled, usually limiting them to feed on decaying plant matter. Most millipedes rarely, if ever, damage garden plants and provide a valuable function as macrodecomposers that accelerate the cycling of nutrients. However, the spotted snake millipede (Blaniulus guttulatus)1 will damage ripe fruit in contact with soil and can be a significant pest in strawberries and tomatoes resting on the soil. Occasionally, millipedes may damage tender vegetable seedlings and root crops such as carrots. A species often associated with seedling injuries is the greenhouse millipede. Millipedes also sometimes attract attention when they make mass migrations, usually following wet weather. They may collect around building foundations or incidentally enter basement areas during these periods. Despite having a fairly tough body covering (exoskeleton), millipedes are much more sensitive to drying than most insects and will often die within a day once in a building. 532

A. Hyella azteca, a common amphipod in ponds. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

A

B. A “beach flea” amphipod found along the edge of water.

B

WHITNEY CRANSHAW

C D

E

C. Julid millipedes.

F

JIM KALISCH, UNIVERSITY OF NEBRASKA

D. The julid millipede

Blaniulus guttulatus. WHITNEY CRANSHAW

E. Immature form of

Blaniulus guttulatus. WHITNEY CRANSHAW

F. Head of a millipede

showing mouthparts.

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Greenhouse millipedes.

G H

JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Spotted snake millipede in strawberry. WHITNEY CRANSHAW

Most millipedes spend the winter as adults or in a nearly full-grown immature stage. Eggs are laid in clusters in soil cracks or under moist, sheltering debris, usually between early spring and summer. Eggs hatch in a few weeks, and the immature stages are pale-colored and wormlike. As millipedes develop they increase not only in size but also in both number of segments and number of legs (anamorphic development). Newly hatched millipedes usually have only 3 pairs of legs and add more with each molt. Commonly encountered millipedes have usually molted a great many times over the course of 2–5 years before reaching the ultimate adult form. Unlike insects, millipedes continue molting after they have become sexually mature adults. 1

Julida: Julidae, Parajulidae; 2 Polydesmida: Polydesmidae, Paradoxosomatidae

533

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

SPRINGTAILS Springtails1 are small six-legged arthropods that are abundant in soils. In the past they were classified as a type of insect since they similarly possess 3 pairs of legs; they are now considered distinct and often classified as a separate class (Collembola) of arthropods. Springtails are minute, typically about 1⁄100 to 1⁄16 inch. Often most abundant are various “slender springtails” of the family Entomobryidae, which have an elongate body form. Also common are “globose springtails” (Sminthuridae family), which have a large rounded abdomen. Colors of springtails superficially appear rather dull cream, gray, pink, or purplish; however, on very close inspection many have considerable surface patterning and color. Springtails have a simple metamorphosis, differing very little in form as they develop. Unlike insects, springtails may continually molt even after becoming sexually mature—as many as 50 times during their lifetime. They are common in environments of high humidity such as compost, rotting vegetation, and under stones or wood. The common name “springtail” is derived from a unique tail-like structure (furcula) that hooks under the body and, when released, allows the springtail to make short jumps; however, many springtails have a very short furcula or lack it entirely and are unable to jump. The great majority of springtail species feed on fungi, bacteria, and other soil microbes. Others are predators of nematodes and other small soft-bodied animals found in soil. Damage to living plants is very uncommon among the springtails, as their minute, weak mouthparts limit their ability to gnawing only on very soft material; however, a small number of globose springtail species have been associated occasionally with plant injuries. Best known of the springtails associated with plant damage is the garden springtail (Bourltiella hortensis) and the lucerne-flea (Sminthurus viridis), which can make minute pits in young leaves and tender roots. In high numbers, these may cause damage to seedlings, particularly if they feed on the hypocotyl area of emerging plants, which can cause deformed growth. Wounding may also produce points where pathogenic fungi can enter. The occurrence of significant plant damage by any springtails is extremely uncommon, however, and most serve as macrodecomposers that consume dead plant matter and fungi, helping accelerate the processes of decay and nutrient cycling. They can be enormously abundant in the moist soils typical of lawns and gardens, with populations exceeding 1 billion per acre estimated in such favorable environments. Despite their enormous abundance, springtails are rarely observed because of their small size and soil-dwelling habit. One of the sites where they may be most easily observed is in compost, and they are often very abundant associates in worm bins. Some springtails, notably the dark blue to reddish brown species Podura aquatica, are sometimes seen massed in small rafts on the surface of pools of water. Springtails may sometimes migrate into buildings from lawns and landscapes, particularly when hot, dry weather abruptly follows a period of moist conditions favorable to springtails. Soil of houseplants often support some springtails that may be seen on the surface, particularly after watering.  Class Collembola: Sminthuridae, Entomobyryidae, and Onychiuridae are common families

1

534

A

B

C D

E

A. An entomobryid springtail.

F

DAVID SHETLAR

B. Entomobryid

springtail exposed from under board. WHITNEY CRANSHAW

C. Springtails associated

with moist soil. DAVID SHETLAR

D. The springtail

Podura aquatica along the edge of water.

G

DAVID SHETLAR

E. A globose springtail. DAVID SHETLAR

F. Underside of a globose springtail showing forked furcula used for jumping. DAVID SHETLAR

G. Sminthurus viridis,

the “lucerne flea.” WHITNEY CRANSHAW

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

SYMPHYLANS The symphylans (class Symphyla) share many features with their relatives the millipedes and centipedes. They are quite small, however, rarely exceeding ⅓ inch, and thus may be mistaken for springtails. Symphylans are generally white, blind, and possess a pair of legs on most but not all segments; typically there are 10–12 pairs on 15 body segments. One species, garden symphylan (Scutigerella immaculata),1 is a plant pest in parts of North America. Other names for it include “garden symphylid,” “greenhouse centipede,” and “garden centipede.” The latter names refer to its superficial resemblance to centipedes, but symphylans are very distantly related animals and even categorized in a wholly different class from centipedes. Garden symphylan is distributed across much of North America, but its local occurrence is very spotty. Most limiting are suitable soils, as it is usually found only in soils that have high organic matter and large pore spaces. Garden symphylans feed on roots and root hairs of a wide range of vegetables, small fruits, and flowers; grasses are little injured. Most serious damage occurs to belowground parts of plants, with flower bulbs, carrot, potato, radish, and beet being most severely damaged. Roots of young seedlings and transplants can be killed, thereby stunting plant growth. Roots of established plants may develop a gnarled appearance with corky tissues forming around wound sites. Garden symphylan lays eggs in small masses from spring through summer. The young develop rapidly, becoming fully grown in about 2 months. All stages occur in soil, usually in the upper few inches. During hot, dry weather, however, individuals may migrate down a foot or more via soil cracks, earthworm burrows, and other soil channels. Adults remain dormant during cool weather but may be active in fall or even winter if mild conditions occur.  Class Symphyla; Family Scutigerellidae

1

SOIL-DWELLING MITES1 Bulb mites (Rhizoglyphus echinopus, R. robini, R. hyacinthi, R. engeli)2 are common throughout North America, although they are not thought to be native species. Bulb mite damage to living plants is concentrated around points that are injured or have some decay where they may extend wounding assist in spread of root-rotting bacteria and fungi. In high numbers, bulb mites may also damage the growing tips of bulbs, causing distortion. Bulbs of various flowers and vegetables have been recorded damaged, including lily, dahlia, tulip, hyacinth, freesia, gladiolus, onion, and garlic. Bulb mites can continue to develop on bulbs in storage, causing rot, decay, and eventual bulb death. Bulb mites are fairly “large” among mites (ca. 1⁄30 inch), smooth-bodied, and whitish to nearly translucent. They undergo an involved life cycle that may include 5 or 6 stages. Development may be continual as long as temperatures allow, and a generation may be completed in under a month under optimal conditions. Moderate temperatures, high humidity, and abundant food favor development. Dormant stages (hypopi) are produced when overcrowding occurs or the food supply degrades. The bulb mites are one genus in the enormous mite family Acaridae, with species that feed primarily on fungi (“mold mites”), are associated with dead insects, or, as with a few, feed on stored food products, such as the grain mite (Acarus siro)1 and cheese mite (Tyrophagus casei).1 Gardeners are most likely to encounter acarid mites in compost operations, with Sancassania anomala1 being a particularly common species associated with vermicomposting. 536

A. Garden symphylan. DAVID SHETLAR

A

B. Garden symphylan.

B

DAVID SHETLAR

C D F

E

G

C. Bulb mites. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

D. Bulb mite Rhizoglyphus echinops. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

H

E. Acarid mites in the genus

Sancassania associated with vermicompost. WHITNEY CRANSHAW

F. Oribatid mite.

G. Oribatid mite. TOM MURRAY

H. Oribatid mites, acarid mites

and springtails associated with decaying plant matter. DAVID SHETLAR

TOM MURRAY

Oribatid mites 3 are often called “beetle or seed mites” because they usually have hard, shiny bodies that can resemble tiny beetles. The cephalothorax and abdomen G are covered with a brown to black shell-like covering, and many species are able to withdraw the head and legs into this covering when disturbed. Most species are less than 1 ⁄20 inch in length and may just look like a dark dot moving about. Most species found in yards and gardens feed on decaying organic matter and are considered beneficial macrodecomposers. They are common in soil, leaf litter, compost piles, and mulch. Occasionally they will be found on the foliage of plants, where they are usually feeding on surface fungi such as sooty molds or mildews.  Class Arachnida, Order Acari; 2 Group Acariformes, Suborder Astigmata, Family Acaridae; 3 Group Acariformes, Suborder Orbatida.

1

537

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

EARTHWORMS1 Earthworms are well recognized by gardeners and generally well perceived. They can provide immense benefits in accelerating decomposition of organic matter produced by plants and animal manure, and some species are adapted to conditions that allow them to be used in “vermicomposting.” Earthworms can also assist in soil building through mixing of their excreted castings in soil during the course of tunneling, and by improving soil aeration and drainage. Most earthworms found in yards and gardens are not native to North America, with the great majority now present of European origin, particularly in the northern states and Canada. In areas previously covered by the last Ice Age, it is rare to find any species native to the Western Hemisphere. Although several species now have wide distributions, specific earthworms may be localized in occurrence, their presence related to human transport and the favorability of site characteristics such as moisture, soil temperature, soil texture, and soil pH. Feeding habits of earthworms vary. While digging in soil, gardeners will typically encounter the soil-dwelling (epigeic) earthworms which form a loose network of tunnels in the soil that may extend a foot deep. These feed on soil particles, organic matter such as dead roots and plant material incorporated into soil, and microbes. Most are light colored, lacking the dark pigments found on species that frequent the leaf litter and feed above the mineral layer. Gray-blue, yellow, pink, or cream coloration tends to mark species of this habit. Most of the soil-dwelling species are in the genus Aporrectodea.2 Among the common species are A. turgida, A. rosea, A. chlorotica, A. trapezoides, and A. tuberculata. top: The earthworm Apporectodea rosea. Although they tunnel primarily within the soil, some may come to the WHITNEY CRANSHAW surface and excrete waste castings, a habit that can be a nuisance in golf above: Large mound with incorporated plant material (midden) produced course fairways. by nightcrawler. Deep-burrowing (anecic) earthworms form a semipermanent WHITNEY CRANSHAW burrow that may extend several feet in depth. At night, particularly when the soil surface is wet, they are active on the soil surface and pull surface material into the burrow, clearing an area extending several inches from the burrow entrance. The primary species with this habit is Lumbricus terrestris,2 a large species (about 10 inches when full grown), variously known as the “nightcrawler,” “Canadian nightcrawler,” or “dew worm.” Native to Europe, it is now found broadly across the cooler areas of the continent, extending south to around Tennessee in the eastern U.S. Much of the waste castings produced by nightcrawlers are deposited on the surface, particularly around the burrow entrance. Uneaten food material, such as leaf clippings, leaf petioles, twigs, and needles may be incorporated into the castings, producing quite noticeable mounds (middens). These may be a couple of inches wide and an inch high, producing lumps that are readily noticed when walking across a lawn, especially in heavy clay soils. 538

A B

A. Apporectodea trapezoides and surface cast it produced. DAN POTTER, UNIVERSITY OF KENTUCKY

B. Surface castings produced by earthworms in spring. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Nightcrawlers mating

on surface.

DAVID SHETLAR

C

Insects and Other Invertebr ates assOcIated wIth rOOts, tubers, sOIl, and the sOIl surface

earthwOrMs Other earthworms feed above the mineral layer of the soil and do not make permanent burrows. These litterdwelling (epigeic) earthworms live in the top inch or so of soil, among fallen leaves, in thatch, and in other places where dead plant material or animal manures have collected. These types of earthworms are the most heavily pigmented, often dark brown or red on the back, and tend to be smaller than species that more permanently dwell and tunnel in soil. Lumbricus rubellus2 and Dendrodrilus rubidus2 are two of the more common species with this habit, both of which have become widely distributed in large part through their use as fish bait (“jumbo red wrigglers”). In addition, several Asian species of earthworms in the genus Amynthas3 have become introduced. A few of these are commercially reared as fish bait, particularly A. hawayanus (=gracilis), known as the “Alabama jumper” or “Georgia jumper.” Amynthas species are highly active worms and dark-colored reddish brown, with some having a greenish cast. Several of these are proving highly invasive and spreading rapidly, notably A. agrestis, A. diffringens (=cortices), A. hilgendorfi, and A. hupeiensis. The litter-dwelling species are also those used in vermicomposting. Perhaps most widely used is Eisenia foetida,2 often called the “red wriggler.” Other vermicomposting species used most commonly in warmer areas are Perionyx excavatus3 and Eudrilus eugeniae,4 both of which are native to tropical/subtropical areas and intolerant of cold. Not one of the above listed species is native to North America, and several have developed into serious pests, particularly in natural areas. The greatest impact is their ability to rapidly clear fallen leaves and other surface litter, which can greatly change the types of vegetation present. These adverse effects have been most marked in northern hardwood forest. Among the species that have become most invasive and damaging to native ecosystems are several of the “jumpers” (Amynthas species), Dendrodrilus rubidus, and the nightcrawler (Lumbricus terrestris). Earthworms also serve as food for many species of birds, moles, and amphibians, and the introduction of European earthworms has likely been favorable to worm-feeding birds such as robins. Several mammals prey heavily on earthworms, and some of these, notably moles, incidentally produce extensive tunneling as they forage for earthworms, sometimes creating damage to lawns and gardens. Some earthworms (particularly Aporrectodea rosea and A. chlorotica) also serve as hosts for cluster flies (Pollenia species), a type of blow fly that commonly enters buildings beginning in late summer and will stay sheltered behind walls and in attics during it period of seasonal dormancy during the cold months. A few introduced Bipalium species of terrestrial planarians5 are predators of earthworms. The most common species present is Bipalium kewense, sometimes called the “hammerhead worm” because of its broad, half-moon– shaped head. It is a very large species, up to 10 inches in length. Hammerhead A. Amynthas hupeiensis, worms are found outdoors primarily in the southeastern states but are more a type of “green stinkworm.” widely distributed in greenhouses. DAN POTTER, UNIVERSITY OF KENTUCKY B. “Red wriggler” earthworms

in vermicompost.

1

Phylum Annelida, Class Clitellata; 2 Haplotaxida: Lumbricidae;

3

Haplotaxida: Megascolecidae; Haplotaxida: Eudrilidae;

5

Phylum Platyhelminthes, Class Turbellaria; Tricladida: Geoplanidae

WHITNEY CRANSHAW

4

C. Cluster fly, a parasite of certain

earthworms and a nuisance invader of buildings in autumn. WHITNEY CRANSHAW

D. An immature stage of Bipalium

kewense, a land planarium known as a ‘hammerhead worm’. DAVID SHETLAR

E. A mature hammerhead worm. DAVID SHETLAR

540

B C

A D

E

CHAPTER SEVEN

INSECTS AND MITES ASSOCIATED WITH FLOWERS, FRUITS, NUTS, AND SEEDS CODLING MOTH

(Cydia pomonella)1

hosts Primarily apple and pear. Occasionally large-fruited crabapple, apricot, quince, hawthorn, and peach. Often infests developing walnut husks. Damage Larvae tunnel into the fruit of apple, pear, and crabapple. Less commonly they also damage other fruits. Codling moth is the single most important insect pest of tree fruits in North America. Distribution Throughout North America, common Appearance Larvae are pale tan, gray, or pink with a dark head and are found associated with the fruit. Adults are small (½ inch long) gray moths with coppery tipped forewings. Life History and Habits Codling moth larvae spend the winter inside a silken cocoon attached to rough bark or other protected locations around a tree. With warm spring weather they pupate, and the adult moths later begin to emerge around blossom time. The spring appearance of this stage may occur primarily over the course of 1 or 2 weeks but can be much more prolonged if weather is cool. During periods when early evening temperatures are warm (above 60° F) and not windy, the moths lay small white eggs on leaves. The larvae hatching from the eggs may feed first on the leaves but then migrate to the fruit, usually entering the calyx (flower) end. They tunnel the fruit, feeding primarily on the developing seeds. After about 3–4 weeks, the larvae become full grown, leave the fruit, and crawl or drop down from the tree to spin a cocoon and pupate. After about 2 weeks, most—but not all—of the second generation of moths emerge from the pupae. The remaining pupae stay dormant, emerging the following season. (For example, in western Colorado only about two-thirds of the larvae go on to produce a second generation, and fewer than half of their progeny go on to produce a third generation.) Summer moths lay eggs directly on the fruit, and damage by the larvae to fruit is greatest at this time. When full grown, the larvae emerge from the fruit and seek protected areas in which to pupate.

Related Species Larvae of the hickory shuckworm (Cydia caryana) develop within the shuck surrounding developing nuts of pecan and hickory, and this insect is considered one of the most destructive pests of pecans in the U.S. Presently hickory shuckworm is found throughout eastern North America in association with its host, but its range has extended westward into New Mexico. The overwintering stage is a late-instar larva in the old shucks of fallen nuts. Pupation occurs in late winter or early spring and first generation adults begin to emerge in early May. Most egg laying by this first generation will occur on hickory, if available, which produces nuts of suitable size at this time. Eggs may be laid on leaves of pecan during the first generation, but nuts are not suitable for development and few larvae survive; most of those that are successful sustain themselves feeding in and around the galls produced by pecan phylloxera (page 324). Larvae produced in the second, early summer generation feed on the interior of pecans, causing damaged nuts to drop. Moths of the third generation usually appear in August and lay eggs on maturing nuts. At this point in time, pecan shells have hardened and hickory shuckworm caterpillars tunnel through the green shucks. Feeding injuries they produce include delayed maturity and incomplete kernel development. 542

B

C

A

D

E A. Damage by codling moth. WHITNEY CRANSHAW

B. External symptoms of

codling moth damage to apple. WHITNEY CRANSHAW

C. Codling moth larva feeding in core. WHITNEY CRANSHAW

F

D. Codling moth pupa.

G

WHITNEY CRANSHAW

H

E. Codling moth eggs on fruit. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Adult codling moth. WHITNEY CRANSHAW

G. Entry hole produced by codling moth larva. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H. Hickory shuckworm larva and damage. LOUIS TEDDERS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

I. Adult hickory shuckworm pupa. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

J. Adult hickory shuckworm. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

I

J

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

orIental FruItMoth Filbertworm (Cydia latiferreana) is associated with almost all cultivated and wild nuts grown in North America and is particularly common in oak acorns and hazelnut. Winter is spent as a full-grown larva in a cocoon on or in the vicinity of the previously infested host. Pupation occurs in spring, and adults are present over an extended period from late June into October. Eggs are usually laid on leaves, but the larvae migrate to nuts and develop in them. Larval development usually takes less than 1 month, after which the larvae exit to search for a protected site, where they spin a cocoon. One generation per year is normal, but egg laying continues over a period of several weeks. Pea moth (Cydia nigricana) is primarily a pest of dried pea in the northwestern states. Occasionally it also damages green peas where large numbers of dried peas are grown nearby. The overwintering caterpillars pupate in spring, and the adults are present about the time peas flower in later spring. Eggs are laid singly near the flowers, and the caterpillar immediately bores into the developing pods. Larvae feed on the developing seeds and may injure several pods, often leaving little external evidence of infestation. When full grown they move to the soil and form a shelter in which they spend the winter. One generation per year is normal in much of the range, but two may occur in more southern areas.

ORIENTAL FRUIT MOTH

(Grapholita molesta)1

hosts Peach, apricot, and nectarine are most seriously damaged, but plum, cherry, apple, pear, almond, and rose are other hosts. Damage Larval tunneling into twigs causes wilting terminals (“shoot strikes”), and two or three such injuries may be produced by an individual insect. Fruit is damaged as larvae feed randomly through the flesh, not consuming the seeds in the manner of codling moth. Fruit injuries also differ in that entry holes produced by Oriental fruit moth are often inconspicuous. Distribution An introduced species that is widespread in orchards in the eastern and southern U.S. It has spread to California and also occurs in isolated area of many western states. Appearance Adults are small grayish moths, about 2⁄5 inch, that fly just after sunset. Larvae are pink with a brown head, very similar in appearance to codling moth larvae. Life History and Habits Winter is spent as a mature larva in a cocoon on or around a previously infested tree. Adults begin to emerge about the time peach blossom buds begin to show pink, and flights from this first generation may extend for almost 2 months. Eggs are laid on newly emerged shoots, and larvae feed in twigs. A second generation occurs in late spring (California) or early summer (Michigan) and attacks both twigs and fruit. Fruit injuries also occur when larvae move from twigs that harden and become unsuitable. A third generation occurs as peaches begin to mature, and most fruit infestations occur at this time. A small fourth generation is sometimes produced in Michigan and Ohio; five generations per year are normally produced in California.

Related Species Cherry fruitworm (Grapholita packardi) damages blueberry, tart cherry, apple, and peach throughout the northern two-thirds of the U.S. and Canada. Hawthorn and rose are other hosts. Larvae develop in fruit, and individuals may damage several small fruits before becoming mature. They then migrate to nearby canes, stubs of pruned twigs, pithy weeds, or other protected sites and burrow to produce a winter shelter. Winter is spent as fullgrown larvae in cocoons, and pupation occurs in spring. Moths fly and lay eggs over a period of a month during the period when young fruits are present. One generation is produced annually. 544

A. Filberworm adult and pupal case.

B

DONALD OWEN, CALIFORNIA DEPARTMENT OF FORESTRY AND FIRE PROTECTION, BUGWOOD.ORG

B. Filbertworm larva and damage. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Pea moth larva

and damage.

A D

C

ART ANTONELLI, WASHINGTON STATE UNIVERSITY

D. Oriental fruit moth larva in peach.

E

JIM KALISCH, UNIVERSITY OF NEBRASKA

E. Terminal wilting

caused by Oriental fruit moth larval tunneling in peach shoot.

CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

F. Adult Oriental fruit moth. TODD M. GILLIGAN AND MARC E. EPSTEIN, USDA-APHIS ITP, BUGWOOD.ORG

G. Cherry fruitworm

adult.

MARK DREILING, BUGWOOD. ORG

H. Lesser appleworm larva and damage.

F

P. J. CHAPMAN, NEW YORK STATE AGRICULTURAL EXPERIMENT STATION, BUGWOOD.ORG

G H

Lesser appleworm (Grapholita prunivora) is a minor pest of apple and also occurs on cherry and plum. Primary damage to apple occurs when larvae tunnel shallowly under the fruit skin. Twigs are also tunneled. Two generations per year are reported from Michigan to New York. Grapholita delineana, the Eurasian hemp borer, feeds primarily within the stems of hemp; however, larvae present in later generations may spin loose webs over leaves and clusters of developing seeds and damage young seeds. 1

Lepidoptera: Torticidae

545

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

TOBACCO BUDWORM (Heliothis virescens)1 hosts A wide range. Although solanaceous plants such as petunia, nicotiana, and tobacco are particularly favored, tobacco budworm also feeds on geranium, ageratum, chrysanthemum, snapdragon, strawflower, rose, and many other flowering plants. It is rarely a vegetable pest, unlike the corn earworm it resembles. Damage Feeding injuries are concentrated on flower buds, the caterpillars favoring the reproductive tissues. Small larvae may restrict feeding to bud tunneling; later stages may consume entire buds and chew petals. Foliage is rarely damaged, but tunneling of leaf buds may occur. Reduced flower production (“loss of color”) and ragged flowers result from tobacco budworm injuries. Distribution This insect is most damaging in areas of the southern U.S., as hard freezing temperatures can kill overwintering pupae. Mild winter conditions and some migration by the adult moths can allow significant infestations in more northern areas, however. Appearance Tobacco budworm is a moderate-sized insect, and caterpillars can reach 1½ inches when full grown. Color can be highly variable and is related in part to diet. Caterpillars may be nearly black to pale brown, with green and reddish forms also common. Banding may be present and prominent in darker caterpillars but indistinct in others. The presence of tiny “microspines” on some segments of the abdomen is used to separate this insect from the closely related corn earworm (tomato fruitworm/bollworm). The adult moth is a typical “cutworm” form with a wingspan of about 1½ inches. The general color is pale green, and the forewing is marked with 4 light and slightly wavy bands. Pupae, which are found in the soil, are spindleshaped and about ¾ inch long, typical of other cutworms. Life History and Habits Tobacco budworm overwinters as a pupa in an earthen cell buried a few inches beneath the soil surface. In spring, adults emerge and are active in the early evening. After mating, females glue eggs singly onto flower buds and leaves. The young caterpillars emerge and feed on flower buds and petals. They become full grown in about 3 weeks, causing extensive injury. They then drop to the soil and pupate. In northern areas two generations per season are usually produced, with the highest caterpillar populations often occurring in August and early September. Four to five generations occur in the southern states.

Related Species Tomatillo fruitworm (Heliothis subflexa) is a closely related species, and the adults are also quite similar in appearance to H. virescens. The caterpillars specialize in Physalis spp. and can be a serious pest of tomatillo fruit. Another closely related species is H. phloxiphaga, which develops on seeds and flowers of a wide variety of host plants, including sunflower, yarrow, asters, snapdragon, and phlox. 1

Lepidoptera: Noctuidae

546

C F B E

A D

G

A. Tobacco budworm larva chewing on buds of nicotiana. WHITNEY CRANSHAW

B. Geranium bud tunneled by tobacco budworm. WHITNEY CRANSHAW

C. Eggs of tobacco budworm

on geranium buds. WHITNEY CRANSHAW

D. Tobacco budworm larva chewing on petunia petals. JOSEPH BERGER, BUGWOOD.ORG

E. Tobacco budworm pupa. WHITNEY CRANSHAW

F. Adult of tobacco budworm. WHITNEY CRANSHAW

G. Tomatillo fruitworm

larva and damage. WHITNEY CRANSHAW

H. Adult of the tomatillo fruitworm. WHITNEY CRANSHAW

I. Larva of Heliothis phloxiphaga. WHITNEY CRANSHAW

H

I

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

CORN EARWORM/TOMATO FRUITWORM/ BOLLWORM (Helicoverpa zea)1 hosts A wide range, including many vegetables, field crops, fruits, flowers, and weeds. Corn, tomato, pepper, cotton, sorghum, and lettuce are among the crops most seriously damaged. Damage Larvae tunnel into ear tips of sweet corn, bore into various fruiting vegetables, and feed on leaves of lettuce and other vegetables. Corn earworm is considered one of the most destructive insects in the U.S., attacking many of the most important field and vegetable crops. Distribution Throughout North America except extreme northern areas. Where freezing winter temperatures prevent wintering, annual migrations originating from the southern U.S. and Mexico allow corn earworm to recolonize during summer and early fall. Appearance Young larvae are pale-colored but darken as they get older. A range of colors may be present, from pale green to pink or even black. Adult moths are typical cutworm form, with light brown wings that often have a dark spot in the center. Life History and Habits Corn earworm is a tropical/subtropical species, and in parts of the southern U.S., development may be continuous. Winter temperatures limit survival in much of North America, and the species often dies out each year. In the northern U.S. and Canada, infestations arise from annual migrations of the adult moths from the southern U.S. and Mexico. Migration flights typically begin in June, but with favorable weather additional migrations can occur through the growing season. Moths fly at night, feeding on nectar and laying eggs singly on suitable host plants. On sweet corn, eggs are laid on green silks; on tomato and pepper, they are usually laid on the new leaves near flowers of developing fruit. Once corn earworm has migrated into an area, damage may become somewhat cyclical, as peak numbers of eggs tend to be laid during the period around a full moon. Eggs hatch in about 2–5 days, and the young caterpillars begin to tunnel into the plants. Corn earworm caterpillars usually feed for about 4 weeks before becoming full grown. Older larvae become highly cannibalistic, and it is fairly uncommon to find more than one in a single corn ear. When full grown, they drop from the plant, construct a small cell in the soil, and pupate. Adults emerge in 10–14 days and produce the next generation.

Other Fruit-infesting Cutworms Caterpillars of several other species of climbing cutworms are occasionally associated with trees in mid- to early spring. Most widespread is the speckled green fruitworm (Orthosia hibisci),1 which feeds on a wide range of deciduous trees and shrubs, including rose, apple, pear, cherry, peach, plum, crabapple, apricot, hawthorn, poplar, maple, oaks, willow, and white birch. The caterpillars feed primarily on foliage and normally cause little injury, but when developing buds and fruit are present, these may be chewed. These injuries can cause premature fruit drop, but when injuries are small the fruit continues to grow, becoming misshapen because of the injured area, and develops corky tissue around the old chewing wound. Speckled green fruitworm spends the winter underground in the pupal stage. Adults are among the first moths to emerge, in March or April, and females lay eggs singly or in small groups near plant buds. The caterpillars feed on the new leaves and remain on the tree throughout their development. By early June the larvae become full grown, move to the soil and pupate. One generation is produced per year. 548

A. Corn earworm in sweet corn. WHITNEY CRANSHAW

B. Adult corn earworm. DAVID SHETLAR

C. Corn earworm eggs.

A

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

B

D. Young corn earworm larva.

C D

WHITNEY CRANSHAW

E. Corn earworm larvae

showing range of coloration. WHITNEY CRANSHAW

F. Corn earworm larva,

prepupa, and pupa.

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Corn earworm in tomato,

a “tomato fruitworm.” DAVID SHETLAR

E

F

G

H

I

J

K

H. Speckled green fruitworm. WHITNEY CRANSHAW

I. Speckled green fruitworm feeding on rose bud. ROBIN ROSETTA, OREGON STATE UNIVERSITY

J. Speckled green fruitworm feeding on apple. DAVID SHETLAR

K. Pear injured by speckled green fruitworm. WHITNEY CRANSHAW

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FruIt-InFestInG cutworMs, and PIcKleworM Green fruitworm (Lithophane antennata)1 is found throughout North America but is particularly abundant in the Midwest and northeastern states. It is also active early in the season, with moths emerging to lay eggs in late winter and spring when evening temperatures persist above about 50° F for a few hours. Eggs are laid singly or in small masses, and the larvae feed on opening buds, leaves, and young fruit. Other species include pyramidal fruitworm (Amphipyra pyramidoides),1 fourlined fruitworm (Himella intractata),1 and yellowstriped fruitworm (Lithophane unimoda).1 Injury is similar, and several species may be present concurrently. Life cycles vary somewhat, with Lithophane species overwintering as adult moths and pyramidal fruitworm as eggs. Damage to buds of various flowers and developing fruit is also sometimes produced by variegated cutworm (Peridroma saucia).1 1

Lepidoptera: Noctuidae

PICKLEWORM (Diaphania nitidalis)1 hosts Summer and winter squash are most commonly damaged. Cucumber, cantaloupe, and some pumpkins are other hosts. Damage Larvae tunnel buds, blossoms, and fruit. Distribution Pickleworm is restricted by winter weather to parts of southern Florida and Texas; however, northward migrations occur annually into the Carolinas. Appearance Pale in early stages, pickleworm caterpillars darken with age and may be somewhat greenish or pink (turning coppery before pupation) with a dark area behind the head. Full-grown caterpillars are about ½ inch. Adults are attractive moths with about a 1-inch wingspan. The wings are generally margined with a yellowish band, and there is a prominent tuft on the hind end of the body. Life History and Habits Eggs are laid in small groups on buds, flowers, and new shoots. Larvae develop by feeding on the plant over a period of 2–3 weeks and then pupate in a thin cocoon tucked into folds of leaves or among crop debris. Adults usually disperse to weedy or woody areas where they spend the day and return to fields at night. In the extreme southern U.S. where host plants are available year-round, activity may occur continuously. In Georgia and the Carolinas where hosts die out in winter and pickleworm fails to survive, 2–4 generations are typically produced per year following spring migration.

Related Species Melonworm (Diaphania hyalinata)1 is closely related to pickleworm and shares an almost identical host range and distribution in North America. Despite its name, it does not damage watermelon, and cantaloupe is not a favored host. Melonworm larvae are pale yellow-green and restrict feeding almost entirely to foliage. Direct fruit damage is limited to the fruit surface and produces scarring of the rind.

550

B

C

A. Pyramidal fruitworm. WHITNEY CRANSHAW

B. Adult of the pyramidal fruitworm known as the copper underwing. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

A

C. Variegated cutworm feeding on tomato. JIM KALISCH, UNIVERSITY OF NEBRASKA

D

E

F

G

H

D. Pickleworm tunneling squash fruit. GERALD HOLMES, CALIFORNIA POLYTECHNIC STATE UNIVERSITY AT SAN LUIS OBISPO, BUGWOOD.ORG

E. Pickleworms feeding on surface of squash fruit. GERALD HOLMES, CALIFORNIA POLYTECHNIC STATE UNIVERSITY AT SAN LUIS OBISPO, BUGWOOD.ORG

F. Adult pickleworm. CHAZZ HESSELEIN, ALABAMA COOPERATIVE EXTENSION SYSTEM, BUGWOOD.ORG

G. Melonworm. ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

H. Adult melonworm. ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

sPecIes related to PIcKleworM Limabean pod borer (Etiella zinckenella)1 damages various legumes in the western states; it can also be found but is less damaging in some southeastern states. Lupine, black locust, lima bean, snap bean, cow pea, and milk vetch are among the common hosts. Larvae destroy buds and blossoms and later tunnel into pods, destroying seeds and fouling pods with their excrement. Pecan nut casebearer (Acrobasis nuxvorella)1 is found throughout areas where pecans are grown, from Florida to southern New Mexico. Adult moths are first present around late May/early June and lay eggs near the calyx of nutlets shortly after pollination. Newly hatched larvae feed first on buds and may cause flowers to abort. They later bore into the base of developing nutlets, sometimes destroying an entire cluster. Larvae feed for about 4 to 5 weeks and pupate within the nut. Adults emerge in July and lay eggs. Larvae from this second generation feed primarily on pecan shucks, causing little damage. Third-generation larvae feed little, moving to wintering shelter on twigs where they form a protective cocoon (hibernaculum). Cranberry fruitworm (Acrobasis vaccinii)1 is an important pest of blueberry; cranberry and huckleberry are other common hosts. Eggs are laid around the blossom end of the fruit and larvae usually enter the fruit around the stem. Berries can be loosely webbed together, and conspicuous brown frass is kicked out of the fruit as the larvae feed. When full-grown, larvae move to the soil and construct a cocoon among surface debris or dug shallowly in the soil and pupate in late winter. One generation is produced annually. A related species is destructive prune worm (A. tricolorella), also known as mineola moth. It produces similar injuries to cherry and plum in most cherry-producing areas and spends winter as a partially grown larva that returns to feed on buds in midspring. Sunflower moth (Homoeosoma electella)1 is common in the southern and central U.S., developing in flower heads of sunflower, coneflower, zinnia, and related plants. The overwintering larvae are fairly sensitive to cold, but adults are highly migratory and flights from the south-central states may colonize areas into Canada and the northeastern states. Eggs are laid on flower heads and larvae feed on florets and then on the developing seeds, consuming or damaging numerous seeds. They also cover heads with a fine silk which, mixed with plant debris and frass, gives them an unattractive appearance. The caterpillars are quite distinctive, being purplish or reddish brown with light stripes running the length of the body. The genus Dioryctria1 contains several species, collectively known as coneworms, most commonly observed feeding on conifer cones. In the southeastern states, west to parts of Texas, southern pine coneworm (D. amatella) is common in pine seed cones. The young larvae overwinter on the bark and move to the young cones and shoots in late spring. Cankers produced by rust fungi are also commonly colonized. In the northern half of the U.S. and southern Canada, fir coneworm (D. abietivorella) develops in Douglas-fir, fir, pine, and spruce. In cones it leaves a clean, pitch-free exit hole. It does considerable feeding on other parts of the plant, including buds, shoots, and even the trunk, in a manner similar to that of twig- and trunk-boring members of the genus (pages 336 and 430). Among the other species that develop predominantly in cones are spruce coneworm (D. reniculelloides) in spruce and fir, blister coneworm (D. clarioralis) on several southern pines, pine coneworm (D. auranticella) on various pines, notably Austrian, in the Great Plains States, and webbing coneworm (D. disclusa) on various pines in eastern North America. In addition, some larvae of some Eucosma species develop within cones. Eucosma tocullionana2 is a common species associated with cones of eastern white pine. European corn borer (Ostrinia nubilalis)3 is primarily a stem and stalk-boring species (page 358) that affects corn and a wide range of other vegetable and herbaceous ornamental plants. Fruiting structures may also be injured and the borer can be found developing within corn ears, pepper fruit, snap bean pods, and many other plants. 1

Lepidoptera: Pyralidae; 2 Lepidoptera: Tortricidae; 3 Lepidoptera: Crambidae

552

A

B

C

D

E

F

A. Limabean pod borer larvae.

G H

FRANK PEAIRS, COLORADO STATE UNIVERSITY

B. Larva of the pecan nut casebearer. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

C. Pecan nut caseborer damage to

developing pecans.

LOUIS TEDDERS, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

D. Adult of the pecan nut casebearer. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

E. Cranberry fruit larva and damage

to blueberry.

I

J

JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

F. Sunflower moth larva and damage to coneflower. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Adult sunflower moths. PHIL SLODERBECK, KANSAS STATE UNIVERSITY, BUGWOOD.ORG

H. Cone of Austrian pine damaged by pine coneworm. WHITNEY CRANSHAW

I. Webbing coneworm larva in

developing cone.

LARRY R. BARBER, USDA FOREST SERVICE, BUGWOOD. ORG

J. External evidence of feeding injury

by Eucosma tocullionana in white pine cone.

K

L

STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

K. Entry hole produced by European

corn borer in pepper.

RIC BESSIN, UNIVERSITY OF KENTUCKY

L. European corn borer in pepper

fruit.

RIC BESSIN, UNIVERSITY OF KENTUCKY

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

OTHER FRUIT- AND SEED-INFESTING CATERPILLARS Grape berry moth (Paralobesia viteana)1 is an eastern species that develops on grape. The spring generation of larvae is most damaging as larvae web together clusters of flower buds and consume most of them. Tender shoots and newly set berries may also be eaten. Summer-generation larvae develop in the berries and may feed on 2 or 3 berries while developing. Two generations are produced annually, with winter spent as pupae. European grapevine moth (Lobesia botrana)1 has a very wide range of plant hosts but is most often found feeding on wine grapes and flax-leaved daphne. Potentially serious damage can be done to wine grapes when the caterpillars feed on bud clusters, flowers, and fruit. In addition to these direct losses, feeding injuries to fruit also create wounds that allow infections with Botrytis fungi. The first North American detections of this insect were in California in 2009. Banded sunflower moth (Cochylis hospes)1 is common in the northern Great Plains but can be found from northern Texas east to North Carolina. Newly hatched larvae are white with a dark head, but body color changes throughout larval development and can vary from pink or yellow to purple or green at maturity. Females lay eggs in the base of flowers in late July, and larvae first feed on the florets. They later partially consume several seeds before moving to the soil and creating an overwintering cell in which they spend the winter. Pupation occurs the following June. The adult moths are straw-colored with a wingspan of about ½ inch. Several species of leafroller moths (page 128) can cause surface wounding of fruit. The wounding occurs when larvae produce a shelter of leaves that also includes buds and developing fruit. Although these larvae most often feed on leaves, incidental damage to fruit can occur that results in significant distortion of mature fruit. Among the important leafrollers that have potential to damage fruit are eyespotted bud moth (Spilonota ocellana),1 redbanded leafroller (Argyotaenia velutinana),1 obliquebanded leafroller (Choristoneura rosaceana),1 orange tortrix (Argyrotaenia citrana),1 blackheaded fireworm (Rhopobota naevana),1 omnivorous leaftier (Platynota stultana),1 and light brown apple moth (Epiphyas postvittana).1 Caterpillars of navel orangeworm (Amyelois transitella)2 develop in a wide range of fruits and nuts. This species is particularly damaging to fig and almond in southern California. Eggs are laid in fissures of fruit and in cracks of nuts after hulls begin to split. Larvae are cream-colored to slightly pinkish with a reddish-brown head capsule. Peach twig borer (Anarsia lineatella)3 develops as a borer in both twigs and fruit in peach. The firstgeneration larvae, usually present in late April and May, tunnel terminals, producing “shoot strikes” indicated by wilting foliage. Adults from this generation emerge in late spring and subsequently lay eggs on twigs, small leaves, and developing fruit. The caterpillars may move about the plant, and fruit is attacked after the pit begins to harden. Peach twig borer is most common and important as a peach pest in the western U.S. but does occur over much of the country where peaches are produced. Almond and apricots are other hosts, but peach twig borer rarely injures their fruits. Tomato pinworm (Keiferia lycopersicella)3 occurs throughout warmer areas of the southwestern states. Tomato is the primary host, although some related plants such as eggplant, potato, and some nightshade weeds also host the insect. Eggs are laid in small clusters on the leaves, and young larvae mine leaves. Later they emerge and fold leaves, feeding as general defoliators. As the larvae get older, they darken from orange-brown to nearly purplish. Older larvae may tunnel fruit, causing most damage. Fruit injuries are concentrated around the stem end, but tunneling may extend to the core. Activity and reproduction may continue year-round if conditions permit. Seven to eight generations per year are commonly produced in southern California. 554

C A. Larva of a European grapevine moth.

A

B

D

E

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

B. Banded sunflower moth larva. FRANK PEAIRS

C. Fruit surface injury

produced by obliquebanded leafroller. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

D. Adult of the orange tortrix. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

E. Larva of the orange tortrix. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

F

G

F. Larva, pupa and damage to almond by navel orangeworm. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

G. Adult navel orangeworm. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

H. Omnivorous leaftier larva and injury to strawberry. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

I. Peach twig borer tunneling into peach fruit.

H

J

I

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J. Peach twig borer larva and

injury to peach.

EUGENE NELSON, COLORADO STATE UNIVERSITY

K. Peach twig borer larva. ROBIN ROSETTA, OREGON STATE UNIVERSITY

L. Tomato pinworm damage

to surface of tomato fruit. ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

K

L

M

M. Tomato pinworm larvae exposed from leaf mine. JAMES HAYDEN, MICROLEPIDOPTERA ON SOLANACEAE, USDA APHIS ITP, BUGWOOD.ORG

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FruIt- and seed-InFestInG caterPIllars Artichoke plume moth (Platyptilia carduidactyla)4 is the most important insect pest of globe artichoke, but the insect is present over much of North America, where it develops in various thistles. Larvae may feed on all aboveground parts of the plant but create problems when they enter the leaves of the harvestable artichoke buds. This occurs when eggs are laid near buds and early stage larvae typically tunnel into outer leaves, progressively boring more deeply within the buds as they get older. Two generations per year are reported from Minnesota, three from California. Adults are small yellowish-brown moths with unusual wings that are extremely narrow and held perpendicular to the body, giving them a T-shape. This appearance is typical of other members of the plume moth family (Pterophoridae), represented by some 150 species in North America, and it is the odd-looking adults that usually attract attention. Larvae feed on buds and seedpods and occasionally bore into stems of various plants, but rarely produce noticeable injury. A few species associated with cultivated plants include geranium plume moth (Amblyptilia pica),4 which feeds on a wide variety of plants, occasionally damaging buds and flowers of cultivated geraniums and snapdragons; grape plume moth (Geina persicelidactylus),4 which feeds on grape leaves, often feeding within a leaf fold of the terminal leaf; morning glory plume moth (Emmelina monodactyla),4 which feeds on leaves of various morning-glory family (Convolvulaceae) plants; and snapdragon plume moth (Stenoptilodes antirrhina),4 which develops in the buds, seedpods, and stems of snapdragon in California. Cotton square borer (Strymon melinus)5 develops on various legumes and plants in the mallow family (e.g., okra, cotton, hibiscus). Early-stage caterpillars feed on leaves, causing little injury. Older larvae may do some tunneling into pods of bean, okra, and other plants but are rarely abundant in gardens. Cotton square borer occurs throughout the U.S. and southern Canada but is abundant only in the southern U.S. The adult is an attractive butterfly known as gray hairstreak. Winter is spent in the chrysalis, with adults emerging in spring when host plants become available. Eggs are laid singly in plants. Young larvae feed on leaves, and older larvae concentrate more on reproductive tissues. Pupation occurs in a yellow or brown chrysalis marked with black spots. Two generations per year normally occur in the northern part of range and up to four in the south. Larvae of the “yucca moths” develop by feeding on the developing seeds of various Yucca spp.; however, the relationship between these insects and their host plants is mutualistic, as the adult moths are essential to the pollination of the plant. Yucca produce a sticky pollen that is collected by the yucca moths, which then actively move it to the floral stigmas, allowing pollination. At this time eggs are either inserted into the plant ovary (Tegeticula spp.)6 or laid on the pedicel or petals (Parategeticula pollenifera).6 The larvae that subsequently hatch eat a few of the seeds, but allow many to survive. Most yucca moths are within the Tegeticula yucasella complex, which consists of 13 species, all of which develop into moderate-sized moths (wingspan typically ¾–1 inch) that are primarily white or light brown. Each is associated with only a few species of yucca, sometimes only a single species. The range of many has extended with the use of yucca in ornamental plantings, and some are presently found as far north as New England. Citrus peelminer (Marmara gulosa)7 produces meandering, serpentine-form mines under the surface of various fruits in the southwestern U.S. and northern Mexico It is most commonly observed on thinned-skinned citrus, but can develop in fruit of a very wide range of plants, including grape, walnut, and cotton. It can also occur as a cambium miner in twigs of oleander, willow, citrus, and other hosts. 1

Lepidoptera: Tortricidae; 2 Lepidoptera: Pyralidae; 3 Lepidoptera: Gelechiidae; 4 Lepidoptera: Pterophoridae;

5

Lepidoptera: Lycaenidae; 6 Lepidoptera: Prodoxidae; 7 Lepidoptera: Gracillaridae

556

A. External symptoms of injury by artichoke plume moth. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

B. Adult artichoke plume moth. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

A C

C. Larva of artichoke plume

moth.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

D. Adult snapdragon plume moth.

B D

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Damage to pods of

snapdragon by snapdragon plume moth. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Adult of the cotton square borer, the gray hairstreak. WHITNEY CRANSHAW

G. Larva of a cotton

E

square borer.

WHITNEY CRANSHAW

H. Yucca moth. DAVID SHETLAR

I. Yucca moth feeding at flower. DAVID SHETLAR.

F

J. Exit holes made in yucca seed

pods by emerging yucca moths. WHITNEY CRANSHAW

K. Larval tunneling of citrus

rind by citrus peelminer. WHITNEY CRANSHAW

G

H

I

J

K

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FRUIT-INFESTING SAWFLIES European apple sawfly (Hoplocampa testudinea)1 is an introduced species found from New England south to West Virginia and west to Ontario. An isolated infestation also occurs on Vancouver Island, British Columbia. This species can be a serious pest of apple fruit and also damages crabapple. Adults become active around the time apple trees begin to bloom and are present for about 2 weeks. Females lay eggs in the blossoms, and the newly hatched larvae feed on the surface of the young apples. These wounds may cause fruit to abort, but if fruit remains, injuries develop as spiral scars on the skin. After molting, later-stage larvae tunnel into the fruit and ultimately feed about the core. A large exit hole is produced from which reddish-brown frass is continually expelled. The larvae are pale brown with a dark head and very short appendages. They may feed on several fruits in a cluster before becoming full grown. They then drop to the ground and winter in a cocoon. Pupation occurs in spring, a few weeks before adults emerge.

Related Species A few native Hoplocampa species are associated with wild and cultivated cherry, including H. lacteipennis and H. cookei (cherry fruit sawfly). Cherry fruit sawfly is found in the Pacific Northwest, where it has also been reported to occasionally damage plum. 1

Hymenoptera: Tenthredinidae

SCARAB BEETLES FOUND AT FRUIT AND FLOWERS Japanese beetle (Popillia japonica)1 is an important insect pest in much of eastern North America and has recently become established in limited areas within some western states. Larvae are a type of white grub that chew roots of turfgrass and adults damage the flowers and foliage of a wide variety of plants growing in yards and gardens. Flower feeding by Japanese beetle is particularly common on rose and hibiscus. False Japanese beetle (Strigoderma arboricola)1 occurs widely east of the Rockies and is particularly common in the midwestern U.S. The adult is very similar in appearance to Japanese beetle but is slightly dullercolored and lacks the characteristic row of white tufts along the sides. Larvae feed on plant roots and are minor pests of potato, onion, grass, arborvitae, yew, and spruce. Adults are highly attracted to white and may cluster on white flowers during the brief period in early summer when they are active. False Japanese beetle is limited to areas of sandy soil and is known locally as “sandhill chafer” in parts of western Nebraska and eastern Colorado. Adults of rose chafer (Macrodactylus subspinosus)1 feed on leaves and particularly blossoms of a wide variety of plants, producing skeletonizing injuries. Rose and peony are highly preferred. Various berries, peach, cherry, amur corktree, mountain-ash, grape, Virginia creeper, some birches, plum, cherry, and crabapple are other common hosts. Rose chafer contains a toxic heart poison, and birds can be poisoned by eating it.

558

B C

A. Damage by apple sawfly. ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

B. Mating pair of apple sawflies. KARL HILLIG

A D

E

F

D. Japanese beetle feeding rose. WHITNEY CRANSHAW

E. False Japanese beetle feeding on prickly poppy. WHITNEY CRANSHAW

F. Rose chafer on rose hips. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

C. Apple sawfly larva. JOE OGRODNIK COURTESY OF NEW YORK AGRICULTURAL EXPERIMENT STATION

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

scaraB Beetles Found at FruIt and Flowers Rose chafer is restricted to areas of the northeastern U.S. and eastern Canada where light, sandy soils are present. The larvae feed on roots of grasses and some weeds, apparently causing little injury. Adults emerge in June and live about a month. They are about ½ inch and more elongate than most scarab beetles, with gray or brown wings, a generally gray abdomen, and long orange legs. In the southwestern U.S. a related species is present, western rose chafer (M. uniformis), but it is rarely damaging. Asiatic garden beetle (Maladera castanea)1 feeds on leaves and flowers of more than 100 different trees, shrubs, and flowers, including asters, dahlias, chrysanthemums, and roses. Adults are chestnut brown beetles, about 5⁄16 to ⅜ inch long that fly and feed at night. The Asiatic garden beetle is currently found over a broad area of the northeast, from Michigan to New England and southward to South Carolina. Hoplia beetle (Hoplia callipyge),1 also known as “grapevine hoplia,” is a minor pest of certain flowers and fruits in many western states. Injury to white and light-colored roses is most commonly reported, but flowers of ceanothus, calla lily, California poppy, magnolia, lupine, and various legumes are also commonly eaten by adult beetles. Fruit clusters of grape are sometimes destroyed by this feeding, which usually occurs from mid-March through early May. Adults are about ¼ to ⅜ inch long and brownish or reddish brown with silvery scales on the back, providing a mottled appearance. Larvae feed on plant roots. One generation is produced annually. A related species in southwestern Canada that sometimes feed on flowers and small fruits is H. modesta; H. oregona has similar habits in the Pacific Northwest. Bumble flower beetle (Euphoria inda)1 is a moderately large, fuzzy scarab beetle. Adults are sometimes observed, often in Bumble flower beetle feeding on ripe grape. small masses, at ooze from plant wounds and on fermenting fruit. HAROLD J. LARSEN, COLORADO STATE UNIVERSITY Occasionally they damage flowers, including daylily, large thistles, rose, and strawflower. Larvae develop in decaying organic matter, preferring animal manures, and may be common in compost piles. Container-grown plants using fresh compost are sometimes infested by bumble flower beetle larvae, which may incidentally chew on roots. Bumble flower beetle is found throughout most of the area east of the Rocky Mountains. It overlaps in range with E. sepulcralis, which is restricted to eastern states. The common flower scarab, E. kerni, may be common at flowers in the western U.S., feeding on pollen of a variety of garden flowers. Two species of very large, green June beetles in the genus Cotinus are sometimes found feeding on ripe, particularly overripe fruit. In the eastern half of the U.S., ranging into Texas and Kansas, the green june beetle (Cotinus nitida)1 is present. In areas of the southwestern states the related fig eater beetle (C. mutabilis) occurs. Larvae of both are a type of white grub that develop in decaying plant matter. Injury to turfgrass may occur as the larvae tunnel extensively through lawns, feeding little on live roots but disturbing soil and creating large surface mounds. In eastern North America, another large scarab that may be found feeding on leaves and fruit of grape is Pelidnota punctata,1 known variously as the “grapevine beetle” or “spotted pelidnota.” Larvae develop in rotting wood. 1

Coleoptera: Scarabeaidae

560

A

B C

D

E F

A. Asiatic garden beetle at flower. DAVID SHETLAR

B. Hoplia beetle on rose flower. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Green June beetle on ripe fruit. DAVID SHETLAR

D. Euphoria kerni feeding on thistle pollen. WHITNEY CRANSHAW

E. Bumble flower beetle in cardoon flower. WHITNEY CRANSHAW

F. Spotted pelidnota. DAVID SHETLAR

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

SAP BEETLES AND OTHER FRUIT-DAMAGING BEETLES Sap beetles (Nitidulidae family) are common around fermenting fruit, oozing wounds of plants, and areas of decaying vegetation. Most do not cause any direct injuries to fruit or vegetables but are attracted to overripe fruit and can be a nuisance. Some species may also be involved in movement of bacteria and fungi, notably spores of Ceratocystis fagacearum, the causal organism of oak wilt. Approximately 180 sap beetle species occur in North America. Most are oval to nearly rectangular in form and have distinctly clubbed antennae. Several species in the fruitworm beetle family (Byturidae) also damage fruits.

Dusky Sap Beetle (Carpophilus lugubris)1 hosts Maturing sweet corn, most overripe fruits and vegetables, and trees infected with various bacteria and fungi. Damage Unlike most sap beetles, dusky sap beetle can directly injure intact sweet corn ears. Larvae chew on the developing kernels, although there is rarely any external evidence of infestation. Dusky sap beetle has been involved in moving spores of the oak wilt pathogen to wounds of healthy trees. Distribution Throughout most of North America, common. Appearance Adults are about ⅛ inch and dull dark gray-brown with short wing covers, each having a light brown band at the base. Larvae are pale-colored, slightly flattened, with a brown head and a dark area on the hind segment. Life History and Habits Overwintered adults and pupae may be found in piles of discarded fruit, partially buried vegetable debris, or under the bark of trees with oozing wounds. Adults are active on warm days in early spring. At this time they feed and begin to lay eggs around decaying vegetation and on sap or bacterial ooze from damaged trees. Larvae can complete development in as little as 3 weeks, and pupation occurs in the soil. Two to three generations are probably produced in most years. Beetles are attracted to sweet corn shortly after pollen begins to be shed, at about the time that corn silk first begins to turn brown. Dusky sap beetle adults are present from early spring through November, with peak numbers often in late spring and midsummer.

Other Sap Beetles Fourspotted sap beetle (Glischrochilus quadrisignatus)1 is common in the northern U.S. and southern Canada. It is sometimes known as the “picnic beetle” because it is often attracted quickly and in nuisance numbers to ripe fruit, pickled vegetables, and fermented beverages during outdoor dining. It also commonly visits damaged or overripe fruits and vegetables in the field, and it may chew on the silk of sweet corn and readily invade cavities made by corn earworm and European corn borer. Adults are about ¼ inch and shiny black with 4 orange-red spots. G. fasciatus, another common species, resembles fourspotted sap beetle but lacks the distinctive spotting. Strawberry sap beetle (Stelidota geminata)1 is a common pest of strawberry in the eastern U.S. It may aggregate in large numbers on ripening fruit, where the beetles feed and lay eggs. They can be important nuisance problems, particularly in pick-your-own operations. Adults are small (ca. ⅛ inch) mottled brown beetles. Strawberry sap beetle has a more restricted host range than many other sap beetles and is damaging only to strawberry. Two generations are typically produced annually. 1

Coleoptera: Nitidulidae

562

A

B

C

A. Dorsal and ventral views of the sap beetle Carpophilus ligneus. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Sap beetles feeding on ooze from wound of honeylocust. DAVID SHETLAR

C. Dusky sap beetle adults and larvae in sweet corn. EUGENE NELSON, COLORADO STATE UNIVERSITY

D. Dusky sap beetles massed on overripe melon. WHITNEY CRANSHAW

E. A “picnic beetle,” Glischrochilus quadrisignatus. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Larva of a Glischrochilus species sap beetle. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Strawberry sap beetle. TOM MURRAY

D E

F

G H

H. Strawberry sap beetle larvae in strawberry. NATALIE HUMMEL, LOUISIANA STATE UNIVERSITY AGCENTER, BUGWOOD.ORG

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FruIt-daMaGInG Beetles

Other Fruit-damaging Beetles Raspberry fruitworms (Byturus spp.)1 are common insects associated with raspberry and loganberry throughout the northern U.S. and southern Canada. Adults of eastern raspberry fruitworm (B. rubi) emerge in late April or early May, about the time leaves first emerge. They feed on the midrib of the unfolding leaves, resulting in ragged, elongate holes. They may then feed on the unopened flower buds and can destroy an entire bud cluster and further damage leaves in a skeletonizing manner. Eggs are laid on or sometimes in unopened blossom buds. The larvae then bore into the developing fruit and are distinctive in having two rows of light-colored, stiff hairs on the back. When full grown, the larvae drop from the plant and pupate in the soil. One generation is produced per year. The life history is likely similar for western raspberry fruitworm (B. bakeri), common in western areas, and for B. unicolor, found in many areas of Canada. Adults of the spotted asparagus beetle (Crioceris duodecimpunctata)2 are commonly observed on ferns of asparagus. Larvae develop within asparagus seeds. Adults of spotted cucumber beetle (Diabrotica undecimpunctata howardi)2 (also known as southern corn rootworm) feed on leaves and flowers of a wide variety of plants and occur widely across North America east of the Rockies. The overwintering stage is an adult that emerges early in the growing season, and there are subsequent multiple (often 2) generations produced annually, allowing the insect to be present throughout much of the Western spotted cucumber year. In the western states it is replaced by the subspecies western spotted beetle feeding on bean pod. cucumber beetle, Diabrotica undecimpunctata undecimpuncta. Dahlia, KEN GRAY COLLECTION, OREGON STATE UNIVERSITY peony, and hibiscus are among the flowers most commonly damaged by this insect. These insects also chew on the developing fruits and seeds of many garden plants, including green beans, tomato, eggplant, and, occasionally, some tree fruits (apricot, peach); however, cucurbit family plants—melons, pumpkins, squash, cucumbers—are particularly favored. A number of other closely related insects are also commonly associated with fruit and flowers of cucurbits, including striped cucumber beetle (Acalymma vittatum),2 western striped cucumber beetle (A. trivittatum), checkered melon beetle (Paranapiacaba tricincta),2 and western corn rootworm (Diabrotica virgifera virgifera).2 With the exception of the last, the larval stages of all of these also develop on the roots of cucurbits. Those larvae that do develop on cucurbits (“rindworms”) will sometimes move into the rind of fruit lying on the ground (“rindworms”), producing tunnels that scar and, often more importantly, wounds that allow entrance of decay Striped cucumber beetle pathogens. Larvae of the western corn rootworm develop solely on roots of corn, feeding on cosmos flower. WHITNEY CRANSHAW and the adults that emerge in early summer often concentrate feeding on green corn silk. However, they also favor feeding on blossoms and pollen of cucurbits and may be seen in co-occurrence with “cucumber beetles” in squash blossoms. 1

Coleoptera: Byturidae; 2 Coleoptera: Chrysomelidae

564

A

B

C

D

E

F

G H

A. Adult of a raspberry fruitworm, Byturus bakeri. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

B. Larva of a raspberry fruitworm

feeding in cap of ripe raspberry.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Spotted asparagus beetle. WHITNEY CRANSHAW

D. Spotted asparagus beetle

larva feeding on asparagus fruit. WHITNEY CRANSHAW

E. Spotted cucumber beetles,

and one western corn rootworm, in squash blossom. WHITNEY CRANSHAW

F. Spotted cucumber beetle feeding on flower. WHITNEY CRANSHAW

G. Corn silk clipped by

western corn rootworm. DAVID KEITH, UNIVERSITY OF NEBRASKA

I

H. Fruit scarring by striped cucumber beetle adults.

J

WHITNEY CRANSHAW

K

I. Striped cucumber beetle larva on

surface of melon fruit contacting soil. WHITNEY CRANSHAW

J. Checkered melon beetles

feeding on sunflower pollen. WHITNEY CRANSHAW

K. Checkered melon beetle and

striped cucumber beetles on surface of ripe melon. WHITNEY CRANSHAW

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

POLLEN-FEEDING BEETLES COMMON AT FLOWERS Many types of beetles feed on pollen in the adult stage and may be conspicuous at flowers. In late summer and early fall, soldier beetles (Chauliognthus spp.)1 are often commonly observed on flowers, particularly yellowflowered plants such as goldenrod and rabbitbrush. These are moderately large beetles (ca. ½–¾ inch), predominantly yellow or orange and black, with soft forewings. Large numbers may be seen on particularly favored plants, with many—often most—coupled (male on top). Eggs are laid in masses in the soil, and the larvae develop as predators of insects that occur in or on soil. Common species in eastern North America include C. marginatus (margined leatherwing) and C. pensylvanica (goldenrod leatherwing); C. scutellaris and C. basalis (Colorado soldier beetle) are common species in the High Plains States. Several other genera of soldier beetles also occur in North America that are predators in the adult stage, but the Chauliognathus species limit feeding to pollen. Many blister beetles 2 also feed on pollen and nectar but may feed on flower petals, particularly of legumes. Most often observed are various black or gray Epicauta spp., including the ubiquitous black blister beetle (E. pensylvanica), a very common species east of the Rocky Mountains present on flowers in late summer. Other genera common on flowers include Pyrota spp., often brightly marked with yellow and black, Lytta spp., often with some metallic sheen, and Nemognatha spp., usually pale orange and with elongated mouthparts that allow them to extract nectar from flowers. Larvae of blister beetles develop variously either on eggs of grasshoppers or on bee larvae within nests of ground-nesting bees. Tumbling flower beetles 3 are small (ca. ⅛–¼ inch), wedge-shaped beetles with a distinctive “pintail.” They can make small, twisting jumps when disturbed, producing a tumbling that may allow them to escape predators. Most tumbling flower beetles observed in flowers are in the genera Mordella or Mordellistena, which are either predominantly dark gray or black and brown, respectively. Larval habits of the tumbling flower beetles are poorly known, but the family includes species that develop in decayed wood, as fungivores or predators, or in the pith of plants. In addition to flowers, where they feed on pollen, the adult beetles often collect on dead trees and fallen logs. The antlike flower beetles 4 are small (ca. 1⁄12–⅛ inch) beetles that rarely attract attention except when noticed within flowers. It is a large family of beetles, with more than 230 North American species, but those most commonly found in flowers are in the genera Anthicus, Ischyropalpus, and Notoxus; the last are distinguishable by a hornlike projection of the thorax that extends over the head. Larvae feed on decaying plant matter. Many kinds of soft-winged flower beetles 5 are common at flowers. Most conspicuous are Collops spp., which are about ¼ inch long, brightly patterned, with wing covers that do not completely cover the end of the abdomen. Collops adults do feed on pollen but are primarily predaceous on many small insects that may visit flowers. Other common genera of soft-winged flower beetles found on flowers are less distinctively marked and smaller, including those in the genera Trichochrous and Listrus, which are dark gray or mottled gray. Larvae of most soft-winged flower beetles are thought to be predators that live in the soil.

566

A

B

C D

E

F

A. A soldier beetle, Chauliognathus marginatus. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Mating pairs of the soldier beetle, Chauliognathus

pensylvanica.

WHITNEY CRANSHAW

C. Black blister beetle feeding on pollen. WHITNEY CRANSHAW

D. Blister beetles, Nemognatha species. WHITNEY CRANSHAW

E. Tumbling flower beetles. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. An antlike flower beetle. WHITNEY CRANSHAW

G

H. Soft-winged flower beetles, Listrus species. DAVID SHETLAR

G. A soft-winged flower beetle, Collops quadriguttatus. DAVID SHETLAR.

H

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

Pollen-FeedInG Beetles coMMon at Flowers, and FruIt, Flower, and seed weeVIls Spotted flower buprestids (Acmaeodera spp.)6 are metallic wood borers that feed on pollen and are normally seen resting on flowers. Approximately 150 species occur in North America, most in the southwestern states. Most have some light-colored spotting and are slightly hairy. Larvae develop as borers within plants, but none are considered pest species. Some longhorned beetles7 also visit flowers, particularly daisies, sunflowers, and other composites. Batyle suturalis and B. ignicollis are two species common over a broad area of central North America. Other “flower longhorns” commonly seen at flowers occur in the genera Typocerus, Leptura, and Crossidius. Although all of these develop as borers of plants in the larval stage, none are damaging to cultivated plants. However, some longhorned beetles that are pollen feeders are important as wood borers, notably the locust borer (Megacyllene robiniae)7 (page 440), commonly observed on goldenrod and other yellow-flowered plants in late summer. 1

Coleoptera: Cantharidae; 2 Coleoptera: Meloidae; 3 Coleoptera: Mordellidae; 4 Coleoptera: Anthicidae; 5 Coleoptera: Melyridae;

6

Coleoptera: Buprestidae; 7 Coleoptera: Cerambycidae

FRUIT, FLOWER, AND SEED WEEVILS Adult weevils, or snout beetles, possess an elongated “snout,” at the end of which are chewing mouthparts. These are usually used to chew into plants, and larval stages of many species develop inside seeds, fruits, and flower buds. Weevils present in yards and gardens include representatives of three weevil families: Curculionidae (snout and bark beetles), Attelabidae (leaf-rolling weevils), and Brentidae (straightnosed weevils). Many of the weevils that develop on seeds or fruit are known as curculios, a reference to the family name. Other weevils develop as borers of stems (page 362) or as root feeders (page 472), and a few develop on foliage (page 196) or as leafminers (page 216). The bark beetles (pages 350 and 452) are now also classified as a type of weevil.

Plum Curculio (Conotrachelus nenuphar)1 hosts Plum, apple, and apricot are most seriously damaged, but peach, nectarine, quince, cherry, pear, hawthorn, wild plum, and native crabapple are also hosts. Damage Feeding and egg-laying wounds by adults produce scarring and distortion of developing fruit, often inducing premature fruit drop. This feeding is often characterized as a D-shaped scar on mature fruit. Wounds may provide entry for brown rot fungus. Larvae tunnel fruit of plum, peach, and apricot. Distribution Generally distributed over the eastern and midwestern states and eastern Canada. Localized infestations occur in parts of Utah, the Pacific Northwest, eastern Texas, and Oklahoma. Appearance Adults are generally gray to black snout beetles, about ¼ inch, with light gray and brown mottling. The wing covers are rough with 2 prominent humps and 2 smaller ones. Larvae, found in fruit, are legless, creamy white grubs with a dark head; they are about ⅜ inch when full size. Life History and Habits Adult weevils winter under covering debris in the vicinity of previously infested trees. They begin to move to trees when average spring temperatures exceed 55–60° F for 3–4 days, and migration continues for a month or more. When small fruits become available, females chew a small pit and insert eggs. They then make a crescent-shaped cut below the egg pocket, leaving a small flap of dead skin on the surface of the fruit. 568

A

A. A spotted flower buprestid. WHITNEY CRANSHAW

B. The flower

longhorn Batyle suturalis. WHITNEY CRANSHAW

C. The flower

B

longhorn Typocerus velutinus.

C

JONATHAN YUSCHOCK.

D. Feeding scars produced by plum curculio.

D

DAVID SHETLAR

E. Plum curculio

larva in sour cherry. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Plum curculio adult. DAVID SHETLAR

E

F

Eggs hatch in about 1 week, and larvae feed in the fruit for about 3 weeks. In some fruit, such as apple, larvae survive poorly, apparently crushed by growing tissues. Larvae that develop successfully cut their way out and drop to the soil. They dig and produce a small earthen cell where they pupate. Adults emerge in 4–6 weeks. In most of its range, plum curculio has only one generation per year, and adults feed on maturing apples before moving to hibernation sites. Two generations are reported in Oklahoma and Texas. 569

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FruIt, Flower, and seed weeVIls

Rose Curculio (Merhynchites bicolor)2 Western Rose Curculio (Merhynchites wickhami)2 hosts Rose, particularly wild rose. Damage Rose curculio damages roses by making feeding punctures in flower buds, resulting in ragged flowers. During periods when buds are not common, feeding occurs on the tips of shoots, killing or distorting the shoots. A “bent neck” condition of rose, similar to that which rose midge may produce (page 582), can be caused by rose curculio feeding wounds that puncture developing stems. Distribution The rose curculio is the dominant species east of the High Plains, but it can be found in areas of western North America. The western rose curculio is usually the dominant species found in the Pacific States and east to Colorado and Alberta. Appearance Adults are about 1⁄5 inch with a pronounced dark-colored “beak,” which is longer on the males. In most areas the wing covers, thorax, and head are reddish and the remainder of the body black. In many western states, however, this species may have metallic green or blue-green coloration. Life History and Habits Adults become active in late spring and lay eggs in developing flowers. The larval (grub) stage feeds on the reproductive parts of the flower. Blossoms on the plant, including those clipped off by a gardener, are suitable for the insect to develop. When full grown, the grubs fall to the soil and form an underground cell, pupating the following spring. There is one generation per year.

Other Seed-, Fruit-, and Flower-damaging Weevils Plum gouger (Coccotorus scutellaris)1 makes numerous feeding punctures on the surface of maturing plums, many of which result in a flow of clear ooze at the feeding site. Eggs are laid in some of the punctures, and the larvae develop in the pit. Adults spend the winter in the pit, and removal of infested fruit at the end of the season can help with control. Apple curculio (Anthonomus quadrigibbus)1 is found in the midwestern top: Wound produced in and eastern U.S. and eastern Canada. Damage to apple is infrequent, resulting mostly rose bud by rose curculio. WHITNEY CRANSHAW from feeding punctures that heal as sunken areas on the fruit. Larvae cannot above: Oozing from feeding develop in growing apple fruit, only in early-season dropped fruit. Development wound by plum gouger. most commonly occurs in other hosts, notably amelanchier, hawthorn, and wild WHITNEY CRANSHAW crabapple. Cherry curculio (Anthonomus consors)1 is a minor pest of sour cherry and chokecherry in the Rocky Mountain region. Adults chew small holes in the base of flowers and cause abortion of developing fruit. The skin of older fruit is pitted by this injury. Eggs are inserted into fruit, and larvae tunnel the fruit, ultimately feeding on the pit. One generation is produced per year. 570

A

B

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A. Rose curculio. WHITNEY CRANSHAW

B. Rose curculio

chewing into bud. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Flower petal injuries

produced by rose curculio. WHITNEY CRANSHAW

E

F

D. Bent terminal of

rose resulting from rose curculio feeding wound. WHITNEY CRANSHAW

E. Plum gouger. DAVID LEATHERMAN

F. Apple curculio. DAVID SHETLAR

G. Cherry curculio. WHITNEY CRANSHAW

H. Larva of cherry

curculio in cherry pit. WHITNEY CRANSHAW

G H

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FruIt, Flower, and seed weeVIls In the eastern states, strawberry bud weevil (Anthonomus signatus),1 also known as “strawberry clipper,” can damage strawberry, blackberry, and related caneberries. Adults emerge in spring as temperatures rise above 60° F and initially feed on buds of strawberry and redbud. Some later move to blackberry, raspberry, and dewberry as buds begin to swell on these plants. Small holes are chewed in the buds and an egg inserted. The female then cuts the stem just below the bud, which often drops from the plant. Each female lays about 20–30 eggs, mostly in April and early May. The summer-generation adults appear in early summer and feed on pollen before moving to winter shelters. Strawberry bud weevil is a small (ca. 1⁄10 inch) reddish-brown weevil. Pepper weevil (Anthonomous eugenii)1 is a tropical species that occurs in parts of southern Texas, south Georgia, and Florida. Larvae tunnel the center of pepper fruit and feed on the seed mass. Adults are black weevils, about ⅛ inch, with a sparse covering of tan to gray hairs. Breeding may be continuous throughout the year, with fruit of nightshade an alternate host. Grape curculio (Craponius inaequalis)1 develops in the berries of grape grown in the southeastern states. Adults emerge in mid-June in Georgia and first feed on foliage, producing zigzag chewing wounds on leaves and petioles. They also puncture fruit to feed and lay eggs. Sunflower headclipping weevil (Haplorhynchites aeneus)2 clips the heads of developing sunflowers, coneflowers, and rudbeckia. The adults are shiny black to red-brown weevils, about ⅓ inch, and may first be observed on or very near developing flower heads in early July; females begin laying eggs a few weeks later. In the process of egg laying, females make a series of punctures in the stalk at the base of the flower head. This puncturing causes the stalk to break at the wound site and the head to hang from the stalk and wilt. Eggs are laid in the flower head and the grublike larvae develop while feeding on pollen and decaying tissues of the flower. In autumn they drop to the ground and burrow into the soil, where winter is spent. Pupation occurs in late spring of the following year. One generation is produced per year. In the northern Great Plains, two species of small weevils develop in the seeds of sunflower: red sunflower seed weevil (Smicronyx fulvus)1 and gray sunflower seed weevil (S. sordidus). Adults of red sunflower weevil move to the plants and feed first on the bracts of the developing head, then on pollen. When young seeds start to form, the weevils lay eggs inside them, and the grubs consume much of the seed interior while developing. In late summer they drop to the ground and dig a small soil cell, where they spend the winter in diapause. Pupation occurs the following year. Gray sunflower seed weevil is less damaging, as it lays fewer eggs and lays them earlier, beginning in the early to mid-bud stages. Cowpea curculio (Chalcodermus aeneus)1 develops within the seeds of several wild and cultivated plants, mostly legumes, but is particularly common in cowpea (Vigna spp.). Females chew into pods, lay an egg, and the grublike larvae then consume the developing seeds. Two generations are normally produced per year, and the overwintering stage is an adult. This insect is most abundant in the southeastern states but occurs north to New Jersey and into Kansas and Oklahoma.

572

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A. Adult pepper weevil. ESTEBAN RODRÍGUEZ-LEYVA, POSGRADO EN FITOSANIDAD, COLEGIO DE POSTGRADUADOS, MONTECILLO, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

B. Pepper weevil larva and damage. ESTEBAN RODRÍGUEZ-LEYVA, POSGRADO EN FITOSANIDAD, COLEGIO DE POSTGRADUADOS, MONTECILLO, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C. Grape curculio. NATASHA WRIGHT, COOK’S PEST CONTROL, BUGWOOD.ORG

D. Sunflower headclipping weevil. WHITNEY CRANSHAW

E. Damage produced by

I

J

sunflower headclipping weevil. DAVID SHETLAR

F. Sunflower headclipping

weevil making puncture wound in stem of sunflower. WHITNEY CRANSHAW

G. Larva of sunflower

headclipping weevil in sunflower head. DAVID SHETLAR

H Larva of the red

sunflower seed weevil. FRANK PEAIRS, COLROADO STATE UNIVERSITY

K

L

I. Gray sunflower seed weevil. FRANK PEAIRS, COLORADO STATE UNIVERSITY

J. Red sunflower seed weevil. FRANK PEAIRS, COLORADO STATE UNIVERSITY

K. Cowpea curculio. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

L. Seeds damaged by

cowpea curculio.

GERALD HOLMES, CALIFORNIA POLYTECHNIC STATE UNIVERSITY AT SAN LUIS OBISPO, BUGWOOD.ORG

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FruIt, Flower, and seed weeVIls About 30 species of acorn or nut weevils (Curculio spp.)1 develop in the seeds of oak and various nut trees. Adults are usually brown, about ¼ inch with a prominent snout, particularly on the female. The legless grubs develop in the nuts and are a favored food of squirrels. The most important species is pecan weevil (C. caryae), often the most serious pest of pecan grown in the southeastern U.S. Hickory is also a common host. Adults are active primarily from early August through September. Adults feeding on young nuts can cause abortion and shedding of damaged nuts. Females lay small packets of 2–4 eggs inside the developing nut, and the larvae subsequently consume much of the nut meat over the next month. When feeding is completed, they drop to the ground and dig a small cell in the soil, where they remain for 1 or 2 years before pupating. During winter a mixture of adults and larvae may be found. Other economically important species include large chestnut weevil (Curculio caryatrypes) and small chestnut weevil (C. sayi), both associated with chestnut, hazelnut weevil (C. obtusus), and filbert weevil (C. occidentis). Hickory nut curculio (Conotrachelus hicoriae)1 is common in acorns and hickory nuts. Nuts of black walnut grown east of the Great Plains are infested by black walnut curculio (C. retentus). Wounds produced by adults that chew into the developing nuts in spring are a common cause of June drop. Larvae feed on the developing seeds. The cones of many species of pines growing in western North America may be consumed by larvae of the western pine cone weevil, Conophthorus ponderosae.1 In late spring or early summer, the adults tunnel into the base of second-year cones, excavating the center of the cone where they then lay eggs. The larvae feed on the developing seeds. Hollyhock weevil (Rhopalapion longirostre)3 feeds on the seeds, buds, and leaves of hollyhock. Small feeding punctures in emerging leaves and petals give the plant a ragged appearance. The larvae consume the seeds of the plant. Hollyhock weevils spend the winter in the adult stage, either in protected areas around hollyhock or in seeds. They move to hollyhock plants in late spring and feed by chewing small holes in the buds of the plants. During this time the weevils are commonly observed mating, the female being identifiable by an extremely long “beak.” As flower buds form in June, the females chew deep pits in the buds and lay eggs. The grub stage of the insect feeds on the developing embryo of the seed. After feeding is completed, it pupates in the seed. Adults usually emerge in August and September, but some remain in the seeds, emerging the following spring. There is one generation per year.  Coleoptera: Curculionidae; 2 Coleoptera: Attelabidae; 3 Coleoptera: Brentidae

1

top: Adult of a western pine cone weevil. JAVIER MERCADO, USDA APHIS ITP, BUGWOOD.ORG

above: Hollyhock weevil larva developing within seed. WHITNEY CRANSHAW

574

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A. Acorn weevil. DAVID SHETLAR

B. Acorn weevil chewing into acorn. DAVID SHETLAR

C. Acorn weevil larva. STEVEN KATOVICH, USDA FOREST SERVICE, BUGWOOD.ORG

D. Pair of pecan weevils.

H

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JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

E. Pecan weevil damage and larva. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

F. Chestnut weevil. DAVID SHETLAR

G. Larva of a western

pine cone weevil.

CANADIAN FOREST SERVICE, CANADIAN FOREST SERVICE, BUGWOOD.ORG

H. Cone damaged by western pine cone weevil. USDA FOREST SERVICE-OGDEN, USDA FOREST SERVICE, BUGWOOD.ORG

I. Pair of hollyhock weevils. WHITNEY CRANSHAW

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FRUIT FLIES The fruit flies (Tephritidae family) are a large group of flies that develop in fruits, stems, and leaves of plants. Adults have wings patterned with dark markings. Of the 290-odd North American species, only a few are seriously damaging to garden plants. Other flies that infest fruit include the gall flies (Cecidomyiidae) and the vinegar, or small fruit flies (Drosophilidae). The latter are particularly common on overripe fruit and occasionally are household pests.

Apple Maggot (Rhagoletis pomonella)1 hosts Apple, pear, and large crabapples primarily. Late-season plum and cherry are infrequently infested, although some strains exist that prefer these hosts. Hawthorn is an important wild host in some western states. Damage Most damage results when the young maggots tunnel fruit, producing meandering brown trails that hasten rot. Egg-laying by the adults involves small puncture wounds (often called “stings”) to the fruit surface that cause dimple-like distortions. Distribution Primarily in apple-growing areas east of the Great Plains but has become established throughout much of North America, including isolated areas of the Pacific and Rocky Mountain states. Appearance Adults are picture-winged flies that have distinct black patterning on the wings. They are about 1 ⁄5 inch, generally black with a white spot on the back and a brown head. Larvae are cream-colored, legless maggots associated with the fruit. Pupae are pale yellowish brown, smooth, and somewhat seedlike. Life History and Habits During winter, apple maggot is in the pupal stage, buried shallowly in soil near previously infested trees. Adults emerge in early summer, and females first feed for about 2 weeks on honeydew and other fluids in the vicinity of fruit trees. They then move to apple and begin to lay eggs, which they insert singly under the skin of the fruit. Peak egg-laying tends to occur in mid- to late July. Eggs hatch within a week. Larvae feed in the fruit for 3–4 weeks before dropping to the soil to pupate. One generation is produced per year, with the pupae remaining dormant until the following season.

Related Fruit-infesting Flies Cherry fruit fly (Rhagoletis cingulata),1 also known as cherry maggot, is an important pest of cherry in the north-central and northeastern U.S. and adjacent areas of southern Canada. Initial damage occurs when the adult female “stings” the cherry fruit with her ovipositor, producing small puncture wounds. Eggs are often laid in the punctures, and the immature maggots chew through the flesh of the fruit. Infested berries are misshapen, undersized, and mature prematurely. Cherry fruit flies spend winter in the pupal stage around the base of previously infested trees. In late May, the flies begin to emerge and feed on fluids, including oozing sap from wounds made by puncturing fruit with their ovipositors. They feed for about 10 days before beginning to lay eggs. Females insert eggs under the skin of fruit for a period of 3 or 4 weeks. The immature maggots feed on the fruit, particularly the area around the pit. They become full grown in 2–3 weeks and drop to the ground to pupate. In most areas there is one generation per year. Black cherry fruit fly (R. fausta) has a similar life history and often occurs with cherry fruit fly in orchards. Pin cherry is the common wild host. Western cherry fruit fly (R. indifferens) is found in most of the western states and British Columbia where it develops on sweet, tart, and some wild-type cherries . Adults are present from June to August, most abundant often about the time of harvest. 576

A

B A. Damage produced by apple maggot in apple. WHITNEY CRANSHAW

B. Adult apple maggot. DAVID SHETLAR

C

C. Surface oviposition

wound punctures made by adult apple maggot adults. WHITNEY CRANSHAW

D. Apple maggot

larva in plum.

WHITNEY CRANSHAW

E. Adult cherry maggot. TOM MURRAY

F. Mating pair of western cherry fruit flies. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G. Western cherry fruit

D

E

F

G

fly larva in cherry fruit. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H. Western cherry fruit fly eggs laid under surface of cherry fruit. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

I. Western cherry fruit fly pupae. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J. Western cherry fruit

fly.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

H

I

J

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

FruIt FlIes Walnut husk fly (R. completa) is native to the south-central U.S. but has become widespread throughout western North America. The maggots tunnel the flesh of walnut husks, which stains the nuts and reduces value. Uncommonly this species also develops in late-ripening varieties of Blueberry maggot larvae and damage. peach. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG Blueberry maggot (R. mendax) is distributed throughout the eastern U.S. and Canada. Larvae develop in blueberry and huckleberry. This species is mostly a pest of commercial blueberry. In the southeastern U.S., adults emerge in late May and persist until late July, when their native host, deerberry, is fruiting. Females lay eggs singly in fruits, and larvae take about a month to develop. The pupae subsequently overwinter, sometimes for a second year before adults are produced. Adults of currant fruit fly (Euphantra canadensis)1 are generally yellowish with bright green eyes. Larvae develop in red and white currants and gooseberries. Eggs are inserted into the developing berries, and a red spot often develops at these oviposition wound sites. The larvae develop in the fruit, tunneling around the Pepper maggot larvae and seeds, and become full grown about the time the fruit ripens. They damage. then drop to the ground, dig into the soil, and pupate, the form in JUDE BOUCHER, UNIVERSITY OF CONNECTICUT which they subsequently overwinter. 1 Pepper maggot (Zonosemata electa) is found in much of eastern North America and is native species thought to have originally been associated with horse nettle (Solanum carolinense). Cultivated peppers are damaged by adults when inserting eggs into the fruit surface, producing small dimpled wounds. More serious damage is caused by the larvae thatfeed on the flesh of the fruit core, producing brownish areas. Although widespread and fairly common, this species is rarely abundant and injuries are often overlooked. Only one generation is produced, and winter is spent as a pupa in the soil. Eggplant, tomatillo, and some wild nightshade weeds also host pepper maggot. Feeding at the base of florets and minor damage to seeds are commonly produced by sunflower seed maggot (Neotephritis finalis).1 Many other aster family plants may also be infested by sunflower seed maggot. Tunneling into the receptacle at the base of the florets may occur with Gymnocarena diffusa,1 which often pupates at the base of the head. There are several tropical species of fruit flies, not established in the continental U.S., that have significant potential to damage crops. These species are surveyed intensively to identify accidental introductions at an early stage. Efforts to eradicate the insect often follow detections. Mediterranean fruit fly (Ceratitis capitata)1 has demonstrated ability to seriously damage a wide variety of fruit crops. It has been introduced, and subsequently eradicated, on several occasions in the continental U.S.; it is permanently established in Hawaii. Oriental fruit fly (Batrocera dorsalis)1 has been introduced into Florida but subsequently eradicated. Mexican fruit fly (Anastrepha ludens)1 is presently known from some Texas counties near the Mexico border. 1

Diptera: Tephritidae

578

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B

C

D

E

F

G H A. Walnut husk fly. DAVID SHETLAR

B. Walnut husk fly larvae. WHITNEY CRANSHAW

C. Adult of the blueberry maggot. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

D. Currant fruit fly larvae in gooseberry.

I

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Currant fruit fly pupae. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Currant fruit fly adult. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

J

G. Adult pepper maggot. GARY STECK, FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES

H. Larva of Gymnocarena diffusa in the base of sunflower. FRANK PEAIRS, COLORADO STATE UNIVERSITY

I. Mediterranean fruit fly. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

K

J. Adult of Gymnocarena diffusa. WHITNEY CRANSHAW

K. Mexican fruit flies. JACK DYKINGA, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

L

L. Oriental fruit fly. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

SPOTTED-WING DROSOPHILA

(Drosophila suzukii)1

hosts Spotted-wing drosophila is found in a wide variety of soft fruits, especially raspberries and blackberries. Other commonly grown fruit crops that can be damaged include strawberries, cherries, blueberries, grapes, peaches, plums, currants, and mulberries. Fruit of many ornamental plants such as yew, chokeberry, and some hawthorns are also hosts. Damage Damage is caused when the larvae feed on ripening fruit. In addition to insect feeding injuries, decay organisms (fungi, bacteria) often develop in the damaged fruit, further accelerating its softening. The very rapid fruit softening, combined with the presence of the larvae, often cause affected fruit to be discarded. Distribution Spotted-wing drosophila was first detected in North America in California in 2008. Within six years after initial discovery it had been reported from at least some areas within essentially every state and throughout much of southern Canada. Ultimately it is likely this insect will be present almost everywhere that susceptible fruit crops are grown in the U.S. and Canada. Appearance The adult spotted-wing drosophila is a small fly about ⅛ inch long. It is closely related and quite similar in appearance to many other Drosophila species, the common “vinegar flies” or “small fruit flies” associated with the yeasts of overripe fruit and other fermenting materials. The adult male is distinguishable by a small dark spot on the wings. Identification of the females requires close, microscopic examination of the ovipositor, which is substantially larger and more serrated than those “vinegar fly” Drosophila species that limit feeding to yeasts. The larvae of spotted-wing drosophila are tiny, cream-colored maggots found in the ripening fruit. Life History and Habits Spotted-wing drosophila survives winter in the adult stage, with the flies remaining in a semidormant condition (diapause) during the cold months. During this time they may use many different sites for winter protection, but areas within the skins and husks of decaying fruit can be particularly important places where they will survive winter. With the return of warm weather in spring, the adults emerge and seek out honeydew, nectar, and oozing sap to sustain themselves. As ripening fruits become available in late spring and early summer, egg laying resumes. When laying eggs, the female creates a small slit in fruit skin and inserts 1–3 eggs. This ovipositioining is repeated over a period of weeks, and a single female can lay up to around 350 eggs in her lifetime. Depending on temperature, the eggs can hatch in 12–72 hours. The larvae then feed inside the fruit, becoming full grown in approximately 5–7 days. Larvae may then either remain inside the fruit to pupate or crawl away to pupate in a sheltered location around the base of the plant. Adults emerge from the pupae in about a week and feed for a brief period on nectar and honeydew before beginning to lay eggs for the next generation. During a year, numerous generations may be completed, perhaps a dozen or more in favorable climates, and peak populations tend to occur in later-maturing fruits (e.g., fall-bearing raspberries). Some continued development may occur during warm periods in autumn, when dropped fruit often serves as the food.

580

A

B A. Spotted-wing drosophila larvae in raspberry.

C D

WHITNEY CRANSHAW

B. Spotted-wing drosophila

adult on raspberry.

HANNAH BURRACK, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

C. Adult male spotted-wing

drosophila showing spot on wing. HANNAH BURRACK, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

D. Spotted-wing drosophila female showing prominent ovipositor. ERIC R. DAY, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BUGWOOD.ORG

E. Eggs of spotted-wing

drosophila adult on strawberry. HANNAH BURRACK, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

F. Spotted-wing drosophila larvae in strawberry. HANNAH BURRACK, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

E

F

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

VIneGar FlIes and sMall FruIt FlIes, and rose MIdGe

Other Vinegar Flies and Small Fruit Flies1 hosts Almost any overripe fruit or fermenting materials that support growth of yeasts. Damage Vinegar flies are attracted to wounded or overripe fruits and vegetables that support fermenting yeasts. They do not cause direct injury to growing plants but can become serious pests of harvested produce as tunneling by the tiny maggots hastens fruit rotting. The small flies can also be annoying in kitchens, at beverage container recycling sites, around compost piles, and in worm beds where foods suitable for breeding are present. Distribution Throughout North America, common. Several species may be common, including Drosophila melanogaster, D. convexa, D. simulans, and D. funebris. Appearance Adults are tiny flies, about 1⁄10 inch. The general body color is often yellowish or light brown, sometimes gray, and the eyes are large and reddish. Life History and Habits Vinegar fly larvae develop on the yeasts that grow on well-ripened fruit and around wounds of plants. Food residues in beverage containers or garbage cans also commonly support growth of yeasts and serve as breeding sites. Adults lay eggs in these areas, and the young maggots can become fully grown in less than a week. Prior to pupation, the larvae migrate away from the food source and attach themselves tightly to plant stems, container walls, and other dry areas. Individual adults live about 4 weeks, with females capable of laying a few dozen eggs daily. Breeding is continuous throughout the warm season, and numerous generations are produced, with peak populations developing in late summer and early fall. Outdoors, vinegar flies go into dormancy during the cool season; indoors they may breed year-round. The African fig fly (Zaprionus indianus),1 like most of the vinegar flies, is considered a secondary pest, developing in overripe or damaged fruit, including fruit damaged by spotted-wing drosophila. It is larger than Drosophila species and also distinctly striped. African fig fly was first detected in Florida in 2005; since then it has spread extensively through North America. 1

Diptera: Drosophilidae

ROSE MIDGE

(Dasineura rhodophaga)1

hosts Rose, particularly hybrid tea types. Damage The small maggot stage of rose midge feeds by making small slashes in developing plant tissues to suck the sap. Developing flower buds are distorted by this injury or may be killed, resulting in “blind” shoots on which no flower buds appear to form. Distribution Localized in many areas throughout North America. Appearance Adults are small, delicate flies, about 1⁄15 inch and brown with a reddish tinge. Larvae are tiny maggots, creamy white to pale red and found about the base of buds. Life History and Habits Rose midge overwinters in the pupal stage in the soil. The adult, an inconspicuous small fly, emerges in late spring, sometimes after the first crop of blossoms. Adults live only 1 or 2 days, but during this time the females lay numerous eggs under the sepals, in opening buds, and in elongating shoots. Hatching larvae slash plant tissues and feed on sap. Eggs hatch in a few days, and the larvae feed for about a week before dropping to the soil to pupate. The complete life cycle can take about 2 weeks, with numerous generations occurring in a growing season. 582

A

B

C A. Vinegar fly adults on a ripe peach. WHITNEY CRANSHAW

B. Vinegar fly

adult laying eggs on overripe peach. WHITNEY CRANSHAW

C. Vinegar fly

larvae developing in overripe banana. WHITNEY CRANSHAW

D. Vinegar fly pupae.

D

E

WHITNEY CRANSHAW

E. Dead vinegar fly

adults at bottom of glass of cider vinegar. WHITNEY CRANSHAW

F. The vinegar

fly Drosophila melanogaster.

JACK KALISCH, UNIVERSITY OF NEBRASKA

G Adult of the

African fruit fly.

F

G

H

I

JEFFREY W. LOTZ, FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES, BUGWOOD.ORG

H. Damage to rose shoot bud by rose midge. ROBIN ROSETTA, OREGON STATE UNIVERSITY

I. Rose midge larva. ROBIN ROSETTA, OREGON STATE UNIVERSITY

J. Rose bud showing

damage by rose midge. ROBIN ROSETTA, OREGON STATE UNIVERSITY

J

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

Gall MIdGes daMaGInG to Buds, Flowers, and FruIt

Other Gall Midges Damaging to Buds, Flowers, and Fruit Blueberry gall midge (Dasineura oxycoccana)1 infests blueberry and cranberry in the eastern U.S. and is particularly damaging to rabbiteye blueberry in the southeastern states. Larvae that develop in flower buds cause them to dry out and abort. The growing points on twigs may be destroyed, seriously reducing foliage growth. A generation can be completed in as little as 2 weeks, and multiple generations occur during the period of active growth of plants in late winter and spring. Chokecherry fruitgall midge (Contarinia virginianae)1 distorts developing chokecherry fruits, causing them to enlarge and become hollow. Within this galled fruit the bright orange-red maggots develop and feed. Winter is spent in the pupal stage, around the base of previously infested chokecherries. Adults emerge in early spring, around the time of blossoming, and females lay eggs in the flowers. The larvae feed in the fruit until midsummer and then drop to the ground and pupate. There is one generation per year. A related species, hemerocallis gall midge (C. quinquenotata), has become established in parts of British Columbia. It is of European origin and distorts daylily flowers. Flowers of cypress are distorted by the cypress flower gall midge (Taxodiomyia cupressi).1 Several flies are associated with heads of sunflower. Sunflower midge (Contarinia schulzi) develop on buds and emerging flowers and can induce a gross clublike distortion of sunflower heads. Sunflower midge is particularly abundant in Minnesota, the Dakotas, and the Prairie Provinces, where it is sometimes limiting to sunflower production. “Cornsilk flies”2 can be serious pests of sweet corn in Florida and some other areas in the southeastern U.S. This is a complex of small flies (ca. 1⁄6 inch) in the genera Chaetopsis and Euxesta that are most abundant in subtropical and tropical areas; C. massyla, E. stigmatias, and E. eluta are the most common pest species in Florida. Adults are a type of picture-winged fly, with banded wings and a body marked with metallic green or black. These flies are active year-round and normally develop in a wide variety of damaged or culled fruit and vegetable matter. Silks of sweet corn, and sites on sweet corn wounded by other insects, can be highly attractive egg-laying sites for adults. Most damage occurs when larvae extensively damage the silks during pollination, resulting in poor kernel set. The larvae may also move into the ear tip and directly damage developing kernels. Larvae of leafminer flies, such as the vegetable leafminer (Liriomyza sativae),3 normally develop within leaves but will sometimes tunnel under the surface of pods and fruit. 1

Diptera: Cecidomyiidae; 2 Diptera: Otitidae; 3 Diptera: Agromyzidae

584

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A C

D E

F

A. Blueberry gall midge in flower bud of blueberry. BRIAN LITTLE, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

B. Adult of the blueberry gall midge. BRIAN LITTLE, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

C. Chokecherry fruit distorted

by chokecherry fruitgall midge. WHITNEY CRANSHAW

D. Larvae of chokecherry

fruitgall midge. WHITNEY CRANSHAW

E. Flowergalls produced

by cypress flowergall midge. ALBERT (BUD) MAYFIELD, USDA FOREST SERVICE, BUGWOOD.ORG

F. Mining of surface of pea pod by a Liriomyza species of leafmining fly. WHITNEY CRANSHAW

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

YELLOWJACKETS AND HORNETS Yellowjackets and hornets are members of the paper wasp family (Vespidae).1 These are social insects that produce colonies, with nests constructed of paperlike material. Although all can sting, most paper wasps are valuable insects that feed on many garden pests, and they are discussed in chapter 8 as biological control species. Those that can damage plants or interfere substantially with gardening are discussed below.

Western Yellowjacket (Vespula pensylvanica)1 Damage Yellowjackets are rarely directly damaging to plants, although they can become a problem when they feed on ripe fruit. Problems with stinging are most important, particularly as nests are often hidden and accidentally disturbed. Late in the season, serious nuisance problems occur as yellowjackets scavenge for meat and sweets. Western yellowjacket has omnivorous food habits and also feeds on many insects. Distribution Western yellowjacket is broadly distributed from the High Plains to the Pacific Coast. Appearance Adults are generally yellow with numerous black markings, including banding of the abdomen. They have a smooth body, without the numerous hairs found in bees. Life History and Habits The only stage surviving winters is a fertilized female, the potential queen. These females become active during warm days in spring and actively search for suitable sites to initiate a nest. Belowground hollows, particularly abandoned rodent nests, are most commonly used. Other hollows such as those found behind walls are also used. A queen subsequently begins to build nest cells of paper which she creates from chewed plant fibers, often obtained from weathered wood. As these cells are created, she begins to lay eggs into them and subsequently feeds the developing larvae meat she collects. Living and dead insects, dead earthworms, and carrion may be used for food. The first yellowjackets reared are considerably smaller and are infertile female workers. These begin to take over the functions of nest-building and rearing young. Colony size increases exponentially during the summer and by early fall may include one to several thousand individuals. Toward the end of the season, some larger rearing cells are built in which fertile females are produced. At this time males also begin to be produced and mating occurs outside the nests. At the end of the season, rearing slows and colonies begin to break up. All workers, the founding queen, and males die, with only new fertilized females surviving to disperse to find shelter in various protected sites. The old nests are abandoned and not reused.

Other Yellowjackets and Hornets Thirteen Vespula species occur in North America and some can be common species. Eastern yellowjacket (V. maculifrons) occurs broadly across areas east of the Great Plains. German yellowjacket (V. germanica) is mostly restricted to the northeastern U.S. The prairie yellowjacket (V. flavipilosa) occurs in the Midwest and northeast, and the southern yellowjacket (V. squamosa) in the southeast. The last occasionally produces colonies that survive a winter and may become very large. All these yellowjackets are primarily predators early in the season when rearing young, then increasingly switch to high-carbohydrate foods such as nectar and honeydew when new potential queens and males are being produced. 586

A

B

C

D

E

F

G H

A. Western yellowjacket feeding on ripe apple. WHITNEY CRANSHAW

B. Western yellowjacket feeding on fried chicken. WHITNEY CRANSHAW

C. Belowground paper nest

of the western yellowjacket.

I

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Western yellowjacket queen

J

gnawing on weathered wood for nest construction material. WHITNEY CRANSHAW

E. Eastern yellowjacket. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Nest entrance of an

eastern yellowjacket colony. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. German yellowjacket queen.

K

L

DAVID SHETLAR

H. Early season nest of a German yellowjacket. DAVID SHETLAR

I. German yellowjacket larvae and capped cells of pupae. DAVID SHETLAR

J. Partially excavated eastern

yellowjacket nest. DAVID SHETLAR

K. A deconstructed late season

nest of German yellowjacket. DAVID SHETLAR

L. German yellowjacket male. DAVID SHETLAR

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

YellowJacKets and hornets, and Gall wasPs aFFectInG nuts Baldfaced hornet (Dolichovespula maculata)1 and the closely related aerial yellowjacket (D. arenaria) produce large, aboveground paper nests in trees, dense shrubbery, and sheltered areas beneath overhanging roofs. Although these species are capable of stinging, their conspicuous nests greatly lessen the likelihood of accidental disturbance. Also, as their diets consist almost entirely of live insects, they do not scavenge as do many yellowjackets. In late summer they will collect honeydew, feed on nectar and pollen, and sometimes also chew on well-ripened fruit. European hornet (Vespa crabro germana)1 is a very large wasp that constructs its paper nests in a manner similar to yellowjackets: in hollows of trees or behind walls and in holes in the ground. It sometimes does considerable damage in late summer to certain trees and shrubs by chewing bark, which it uses to form its paper nest. Lilac, boxwood, birch, willow, mountain-ash, and poplar are among the plants most commonly damaged. Affected twigs and branches often wilt permanently and may die back following these injuries. The European hornet is presently known from most eastern and midwestern states and parts of southern Ontario. The European hornet is often mistaken for the Asian giant hornet (Vespa mandarinia) which is a larger and more aggressive species that has not been established in North America.

above: European hornet feeding on ripe fruit. DAVID SHETLAR

right: Distorted terminal growth of chestnut produced by Asian chestnut gall wasp. DAVID SHETLAR

GALL WASPS AFFECTING NUTS Oriental chestnut gall wasp (Dryocosumus kuriphilus)2 produces galls in the shoot tips, leaves, and catkins of chestnut. Shoot growth and nut production can be severely reduced by infestations. This insect was first detected in North America in 1974 and has since spread to most of the Mid-Atlantic region and west to Tennessee and Ohio. Several native gall wasps develop in acorns of oak. Callirhytis fructuosa2 and the pip gall wasp (C. operator) are among the common species. Both develop in acorns of red oak. 1

Hymenoptera: Vespidae; 2 Hymenoptera: Cynipidae

588

A

B

C D

A. Baldfaced hornet nest.

E

WHITNEY CRANSHAW

B. Baldfaced hornet chewing

on wood.

JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Baldface hornet nest cut away

to show internal construction.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. Aerial yellowjacket. WHITNEY CRANSHAW

E. Bark chewing by European hornet. JIM BAKER, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

F

F. Adult of the Asian chestnut gall wasp.

G H

JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

G. Larvae of the Asian chestnut

gall wasp.

JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

H. Adults of the Asian chestnut gall wasp in gall. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

I. Galls produced in acorn by Callirhytis fruticosa. LARRY R. BARBER, USDA FOREST SERVICE, BUGWOOD.ORG

J. External evidence of acorn damaged

by the gall wasp Callirhytis operator.

LARRY R. BARBER, USDA FOREST SERVICE, BUGWOOD.ORG

I

J

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

WESTERN FLOWER THRIPS

egg

First-instar nymph

(Frankliniella occidentalis)1

hosts A wide range of herbaceous plants, including both broadleafed second-instar and grasses. nymph adult Damage Scarring injury to flowers is the most common concern to gardeners. In the landscape, injuries are usually minor, but occasionally they seriously blemish or distort flowers. Feeding injuries to vegetables typically involve slight scarring. Cloudy “pansy” or “halo” spots may be produced on fruit around egg-laying puncture wounds. Western flower pupa Prepupa thrips is also a highly efficient vector of viruses in the tospovirus group, which can produce the plant diseases tomato spotted wilt, impatiens Generalized life cycle of a thrips. ILLUSTRATION COURTESY OF UNIVERSITY necrotic spot, and iris yellow spot. OF CALIFORNIA STATEWIDE IPM PROGRAM Distribution Formerly limited largely to western states but now found throughout most of North America. It is particularly common in the southern half of the U.S., where it can be a major pest of vegetable crops. Western flower thrips is one of the most important greenhouse pests throughout the continent. Appearance Difficult to distinguish from most common thrips on leaves and flowers without high magnification. Adults are about 1⁄16 inch, slender, and range from yellow to brown. Nymphs are yellow. Life History and Habits Flower thrips are moderately cold hardy and likely survive winter outdoors in much of the southern half of the U.S. In warmest areas, and in greenhouses, reproduction may be continuous as long as conditions permit. Elsewhere flower thrips may winter under leaf debris or other protected sites. Adults feed on pollen in addition to plant sap. Females insert eggs into emerging leaves, buds, and flowers. Eggs hatch in about 5–7 days, but this period can be extended considerably with cool temperatures. Subsequently there are two larval (nymphal) stages that actively feed and produce most of the physical plant injuries. Depending on temperature, the larval stages are normally completed in 1–2 weeks. Two nonfeeding stages (prepupa, pupa) then occur, usually in soil. Another week or so is required for completion of these stages, after which the adult is present to repeat the cycle. Multiple generations occur outdoors, and breeding may be continuous in greenhouses. Mass movements frequently occur in summer following the decline of flowers and other alternate hosts.

Related Species Flower thrips (Frankliniella tritici) is a native insect, found primarily in eastern North America. Its habits and hosts are similar to those of western flower thrips, but it has been less important as a vector of tomato spotted wilt and impatiens necrotic spot viruses. Tobacco thrips (F. fusca) is common east of the Rockies and particularly abundant in the southeastern U.S. It develops on grasses and many vegetables but is primarily a pest of field crops such as cotton, tobacco, alfalfa, and peanut. Tobacco thrips can also transmit tomato spotted wilt virus. Scarring of flowers and developing seeds or fruit also occurs with other species of thrips. Among these are gladiolus thrips (Thrips simplex)1 on gladiolus; melon thrips (T. palmi) on a variety of fruiting vegetables; citrus thrips (Scirtothrips citri)1 on certain citrus; and avocado thrips (S. perseae) on avocado. 1

Thysanoptera: Thripidae

590

A D

B

C

E

A. Adult western

flower thrips. DAVID SHETLAR

B. Oviposition wound

in snow pea produced by western flower thrips. WHITNEY CRANSHAW

C. Nymph of a

flower thrips.

F

BRUCE WATT, UNIVERSITY OF MAINE, BUGWOOD.ORG

D. Side view of a thrips showing blade-lake ovipositor at hind end. ALTON N. SPARKS JR., UNIVERSITY OF GEORGIA, BUGWOOD.ORG

E. Oviposition wounds

G

in tomato produced by western flower thrips. WHITNEY CRANSHAW

F. Western flower thrips injury to English daisy. WHITNEY CRANSHAW

G. Western flower thrips

injury to sweet pea. WHITNEY CRANSHAW

h. Surface scarring of

peach by thrips feeding.

H

HAROLD LARSEN, COLORADO STATE UNIVERSITY

I

i. Galdiolus thrips injury to blossom. WHITNEY CRANSHAW

j. Surface scarring of

avocado by avocado thrips.

MARK S. HODDLE, UNIVERSITY OF CALIFORNIA-RIVERSIDE, BUGWOOD.ORG

K. Citrus thrips injury

to orange.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

J

K

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

TARNISHED PLANT BUG

(Lygus lineolaris)1

hosts Mostly herbaceous garden plants and weeds, particularly composites and legumes. Peach, apricot, and strawberry are among the fruit crops most commonly damaged. Damage Tarnished plant bug feeds on developing leaves, fruits, and flowers, killing the areas around the feeding site. This can cause abortion of young flowers, developing seeds, or fruit. Death of buds may lead to abnormally bushy growth. Older tissues may continue to grow but be deformed. Catface injuries to fruit are among the commonly observed distortions caused by tarnished plant bug feeding. Distribution Throughout North America. Appearance Adults are generally oval, about twice as long as wide, and about ¼ inch long. They are generally brown with some yellow and reddish markings. Color tends to darken with age. Nymphs are more rounded in form and usually yellowish green to dark green, often with dark spotting. Life History and Habits Winter is spent in the adult stage under the cover of piled leaves, bark cracks, or other sheltered sites. Adults emerge and become active in early spring, feeding on buds of trees and shrubs. Most then move to various weeds and other plants, and females insert eggs into the stems, leaves, and buds of these plants. The young hatch, feed, and develop on these plants, becoming full grown in about a month. Several generations are produced during the year. Tarnished plant bug is an omnivore that also feeds on aphids and other small, soft-bodied insects, effecting some biological control of these pests that is considered beneficial.

Related Species Thirty-four species of Lygus occur in North America, and most have similar life histories. Pale legume bug (L. elisus) is a common and damaging species found west of the Mississippi. Pale legume bug has a broad host range and, despite its name, is most commonly associated with cabbage family plants. Western tarnished plant bug (L. hesperus) is largely restricted to areas west of the Rockies. It has a wide host range that includes vegetables, seed crops, alfalfa, and some fruit. Campylomma bug (Campylomma verbasci),1 also known as mullein bug, is found widely over southern Canada and northern U.S. It is sometimes considered a tree-fruit pest, particularly of apple; first-generation nymphs feed on developing fruit, causing abortion or corky warts to develop on the fruit surface. Later in the season, campylomma bug is beneficial to orchardists as a predator of aphids, mites, and pear psylla. Summer activity occurs primarily on various weeds, particularly common mullein. Winter is spent as eggs inserted into apple and pear twigs. The genus Lopidea1 includes some relatively small (ca. 1⁄6 inch), brightly colored plant bugs, often with prominent scarlet markings. Phlox plant bug (L. davisi) damages the buds and distorts the flowers of phlox in the midwestern U.S. Feeding by L. confluenta is associated with bud abortion on daylily and iris in the southern U.S. The “tomato bug” Engytatus modestus1 feeds on the young shoots, buds, and developing flowers of tomato. Feeding wounds, in the form of small punctures, tend to be concentrated at specific sites on stems, producing cumulative wounding that causes flowers and fruit to drop. The tomato bug has a wide host range, but tomato is the only plant that may sustain serious damage. The tomato bug is present primarily in the southwestern U.S., from Texas to southern California, but has been found in Hawaii and some eastern states. 1

Hemiptera: Miridae

592

A

B

C

D

E

F

G H A. Tarnished plant bugs on flower bud. DAVID SHETLAR

B. Tarnished plant bug

injury to flower petals. WHITNEY CRANSHAW

C. Pale legume bug. WHITNEY CRANSHAW

I

J

D. Western tarnished plant bug. WHITNEY CRANSHAW

E. Tarnished plant bug nymph. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

F. Tarnished plant bug nymph on strawberry. JEFF HAHN, UNIVERSITY OF MINNESOTA

G. Plant bug feeding wound

in young pear.

WHITNEY CRANSHAW

H. Catfacing injuries to pear resulting from plant bug wounding. WHITNEY CRANSHAW

K

L

I. Campyloma bug. BRADLEY HIGBEE, PARAMOUNT FARMING, BUGWOOD.ORG

J. Phlox plant bugs. JIM KALISCH, UNIVERSITY OF NEBRASKA

K. Adult of the “tomato

bug” Engytatus modestus. WHITNEY CRANSHAW

L. Nymph of the “tomato

bug” Engytatus modestus. WHITNEY CRANSHAW

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

BROWN MARMORATED STINK BUG

(Halyomorpha halys)1

hosts A very wide range of plants can be fed on and damaged by brown marmorated stink bug, including most tree fruits, various legumes, sweet corn, caneberries, and peppers. Feeding can occur on many types of trees and shrubs, with tree-of-heaven (Ailanthus altissima) and princess tree (Paulownia tomentosa) being particularly favored species. Greatest damage to crops has occurred to apples and pears. Damage When feeding, brown marmorated stink bugs kill the tissues at the feeding site. This can produce a range of effects depending on when and where feeding occurs. The most commonly seen damage is on developing fruit, where feeding results in sunken “catfacing” injuries. Feeding on very young fruits or blossom may cause abortion of these plant parts. Feeding on limbs of trees and shrubs can produce wounds under bark that often weep. However, brown marmorated stink bugs are often most notorious for their habit of commonly using buildings for winter shelter. Very large numbers of these insects may collect indoors, particularly in upper stories, and they can secrete an unpleasant odor when disturbed. Although they do not reproduce during the period indoors, being in a semidormant state (diapause), they may periodically become active and move about, particularly during warm periods. Distribution Brown marmorated stink bug was first detected in Pennsylvania in 1998 and since that time has developed into an important pest throughout the Mid-Atlantic region; however, it is very easily and commonly transported by humans. Established, reproducing populations are present over a wide area of the eastern U.S. Detections of this insect have also been reported from most of the Continental U.S., although in some areas it appears unable to establish or thrive. Appearance The adult insect is about ¾ inch long and of the broad body form typical of stink bugs. It is generally brown with some marbling (marmoration) of the surface. Patches of small punctures on the front half of the body and a series of light markings edge the back of the body. The most useful characteristic to distinguish this from other brown-colored stink bugs (and there are many) is the presence of white banding on the antennae. Immature stages are smaller, a bit more rounded in body form than adults, and lack fully developed wings. Overall coloration is gray to brown, but the abdomen is generally lighter-colored with several darker bands. Life History and Habits Adults usually emerge from overwintering sites (including buildings) in mid- to late April. They first move to trees to feed on developing seeds, fruits, and emerging leaves and stems. After feeding for about 2 weeks, the overwintered adults mate and females begin to lay eggs. Eggs are laid in the form of a mass on the underside of leaves. Typical egg masses have 20–30 light yellow to yellow-red eggs, with the top ridged with fine spines. A series of egg masses, laid at approximately weekly Brown marmorated stink bugs on peach. GARY BERNON, USDA APHIS, BUGWOOD.ORG intervals, may be produced through August. At egg hatch, the first-instar nymphs are tiny, a mixture of black and red, and they remain clustered around the egg mass for a couple of days. After molting again, later-stage nymphs take on a more generally gray to brown color and disperse throughout the plant, although they will sometimes cluster in protected areas of the plant, such as leaf folds. They become full grown about a month after egg hatch, and the adults continue to feed throughout the growing season. In late summer they begin to cease feeding and move to overwintering sites. One generation per year is normally produced in the mid-Atlantic region, although additional generations are possible in warmer climates. 594

B

A. Brown marmorated stink bug on apple. DAVID SHETLAR

B. Brown

marmorated stink bug nymphs. DAVID SHETLAR

C. Brown

A D

marmorated stink bug egg mass.

C

DAVID SHETLAR

E

F

D. Rough stink bug. WHITNEY CRANSHAW

E. Southern green

stink bug.

RUSS OTTENS, UNIVERSITY OF GEORGIA

F. Southern green stink bug nymph. RUSS OTTENS, UNIVERSITY OF GEORGIA

Other Stink Bugs that Feed on Flowers, Fruit, and Seeds Rough stink bugs (Brochymena quadripustulata, B. affinis, B. sulcata, others)1 are dark brown or gray with a slightly scalloped body form. They blend in well with bark and are most commonly encountered on trees. Rough stink bugs are primarily predators of insects but sometimes feed on leaves. They are among the stink bugs with general appearance similar to the brown marmorated stink bug but can be distinguished by lack of banding on the antennae. Southern green stink bug (Nezara viridula)1 is found in the southeastern U.S., where it is considered an important pest of vegetables and field and orchard crops. Legumes and crucifers are particularly favored, but the host range is wide. Feeding on buds and blossoms causes them to wither and die. Feeding punctures in fruit cause deformed growth, and seeds may be shriveled. Adults are about ½ inch long and dull green. The young nymphs are pinkish but turn increasingly green with age. Development is usually completed in 65–70 days, and four generations are typically produced. The adults go dormant with decreasing day length. 595

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

stInK BuGs that Feed on Flowers, FruIt, and seeds

Stink bug damage to pecan. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

Damage to interior of cotton boll due to stink bug feeding wounds. RONALD SMITH, AUBURN UNIVERSITY, BUGWOOD.ORG

Stink bug damage to tomato. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

Green stink bug (Acrosternum hilare)1 is broadly distributed throughout most of the U.S. and southern Canada. It is similar in appearance to southern green stink bug but considered much less damaging. Hosts include most vegetables as well as many fruit trees. One or two generations are produced, depending on temperature and location. Stink bugs of the genus Chlorochroa1 are primarily western in distribution. They are most commonly known to damage small grains but will feed on vegetables and certain flowers. Most are green, but some may be quite dark with purplish or reddish coloration. Common species associated with plant injuries include Say stink bug (C. sayi), Uhler stink bug (C. uhleri), and conchuela (C. ligata). Occasionally these stink bugs will mass on the exterior of buildings, but they do not invade homes during winter. Euschistus1 stink bugs are gray or brown and somewhat more angular in form. A few are minor pests of fruits and buds, including brown stink bug (E. servus), consperse stink bug (E. conspersus), and onespotted stink bug (E. variolarius). Stink bugs of the genus Thyanta1 are generally green but may have colored markings, particularly a rosy border along the scutellum, behind the head. Thyanta custator (redshouldered stink bug) and T. pallidovirens are the most common species in yards and gardens, widely distributed in North America. Like many other stink bugs, they feed on fruit and seeds of a wide variety of plants but rarely cause significant injury. Cosmopepla lintneriana (twicestabbed stink bug) is a generally black-colored stink bug with bold red markings that is widely distributed in North America. They are generalist feeders on seeds of many common garden plants, including thistles, Echinacea, mints, and goldenrod. Five other Cosmopepla species, with more limited distributions, also occur in the U.S. 1

Hemiptera: Pentatomidae

596

A D

E

B

C A. Green stink bug. SUSAN ELLIS, BUGWOOD.ORG

B. Green stink bug nymph. SUSAN ELLIS, BUGWOOD.ORG

C. Conchuela stink bug. WHITNEY CRANSHAW

D. Nymph of the conchuela

stink bug.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Egg mass of Uhler stink

F

G

bug.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

F. Say stink bug. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Brown stink bug. RUSS OTTENS, UNIVERSITY OF GEORGIA

H. Brown stink bug nymph. RUSS OTTENS, UNIVERSITY OF GEORGIA

I. Twicestabbed stink bugs. DAVID SHETLAR

J. Redshouldered stink bug. WHITNEY CRANSHAW

H

J

I

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

BOXELDER BUG (Boisea trivittata)1 hosts Boxelder and caddo maple, primarily. Silver and red maples are other hosts. Damage Nymphs and adults usually feed on sap from seeds, flowers, and leaves but cause little damage to trees. Occasionally they feed on developing fruits, such as apples, and can produce puckered catface injuries to these plants. The major “damage” from these insects is their appearance in nuisance numbers on the windows and porches of homes in cooler months of the year. Their presence is most commonly noted on sunny days in fall and spring. Distribution Throughout North America, east of Nevada. Appearance Adult stages are brownish black, about ½ inch long, with 3 red lines on the head and a bright red abdomen beneath the wings. The nymphs are somewhat more oval in form and predominantly red except where the black wing pads are developing. Life History and Habits Boxelder bugs overwinter in the adult stage in protected sites, often including homes. They emerge in mid-spring and lay groups of rusty red eggs near deposits of dropped seeds of boxelder, other maples, and occasionally ash. The first-generation nymphs feed on these seeds, various low-growing plants, and recently dead insects. They may also be cannibalistic, feeding on other nymphs in the process of molting. They become full grown in early summer. A second generation occurs in late summer. Eggs are laid almost entirely on boxelder, particularly on seeds produced by female trees. The nymphs often develop on these seeds into October if weather permits. After frosts, boxelder bugs move to winter shelter, during which time homes are invaded. Boxelder bugs can move hundreds of yards from boxelder trees.

Related and Similar Species In the western states and British Columbia, western boxelder bug (Boisea rubrolineata)1 is present but not nearly as significant a nuisance pest as boxelder bug. Feeding on developing tree fruits causes pitting and catfacing injuries. Another common black-and-red bug found in western North America and often mistaken for boxelder bug is small milkweed bug (Lygaeus kalmii).2 It develops on seeds of a wide variety of plants, including many weeds, and is not considered a pest. A closely related species, L. angustomariginatus, is common in eastern North America. The larger and more brightly colored large milkweed bug (Oncopeltus fasciatus)2 is a specialist of milkweeds and feeds on the seeds. below: Boxelder bug eggs. right: Small milkweed bugs.

WHITNEY CRANSHAW WHITNEY CRANSHAW

A

B

C

D

E

I

F

G

A. Boxelder bug. DAVID SHETLAR

B. Boxelder bug nymph

feeding on developing cherry fruit. WHITNEY CRANSHAW

C. Boxelder bugs

massing in early fall. WHITNEY CRANSHAW

D. Mixed stages of boxelder bugs on boxelder trunk. WHITNEY CRANSHAW

E. Western boxelder

bug.

DAVID SHETLAR

F. Large milkweed bug. DAVID SHETLAR

G. Large milkweed

bugs massed on milkweed pod. DAVID SHETLAR

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

sPecIes related or sIMIlar to BoXelder BuG Jadera haematoloma,1 known variously as the red-shouldered bug, “goldenrain-tree bug,” and “soapberry bug,” develops on the seeds of goldenrain tree and other soapberries. Noticeable numbers of the insects may be observed massing in the vicinity of host trees in late summer, including walls of buildings, but they do not migrate into buildings for overwintering, unlike boxelder bugs. It is distributed primarily in the southeastern states but is found in other areas in association with its host. In the southeastern states, hibiscus bug (Niesthrea louisianica)1 may be common on hibiscus and rose of Sharon. Eggs are laid in masses on leaves, and the young develop by feeding on buds and seeds. Little damage is produced, but the brightly colored, orange-and-black bugs may become sufficiently abundant to attract attention. Usually one and occasionally two generations are produced annually. More than a dozen species of seed-feeding bugs in the genus Arhyssus1 are present in North America. Many can be commonly found on flowers, although they rarely attract attention, being of moderate size (ca. ⅓ inch), and usually a general brown or greenish coloration. Some are specialists in certain types of plants while others apparently feed on seeds of many plants, including several common weeds found in gardens. None appear to cause significant plant damage. A few species are more important as nuisance invaders of homes in late summer and fall, including A. crassus (“weed bug”) in parts of California and A. lateralis in Colorado, apparently feed on seeds of many plants, especially perennials and annual flowers. A great many other seed bugs are associated with seeds of plants that grow in yards and gardens. Various Nysius2 species, often collectively referred to as “false chinch bugs,” can be extremely common insects in areas of the western U.S. and Prairie Provinces, where they may be seen massing in very large numbers on seed heads. Mustard family plants are favored, but they may also occur on many common weeds, including kochia and pigweeds. Pigweeds, amaranth, and several weeds host various ash-gray leaf bugs (Parapiesma spp.)3 which may mass on seed heads and damage seed production. Seed-feeding bugs are also associated with many shade trees but are rarely observed and cause no noticeable injuries to plants. Sycamore seed head bug (Belonochilus numenius)2 is sometimes abundant enough to attract attention in masses near sycamore trees, and the birch catkin bug (Kleidocerys resedae)2 is a nuisance invader-type species that will enter homes in autumn. 1

Hemiptera: Rhopalidae; 2 Hemiptera: Lygaeidae; 3 Hemiptera: Piesmatidae

False chinch bugs massed on seed pod. WHITNEY CRANSHAW

A B

C

A. Mating pair of red-shouldered bugs. DAVID SHETLAR

B. Mixed stages of

red-shouldered bugs. BOB HAMMON, COLORADO STATE UNIVERSITY

C. An Arhyssus species

of seed feeding bug. WHITNEY CRANSHAW

D. A pair of ash-gray

leaf bugs.

DAVID SHETLAR

E. Birch catkin bug. TOM MURRAY

D

E

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

WESTERN CONIFER-SEED BUG (Leptoglossus occidentalis)1 hosts Seeds within cones of various conifers, particularly pines, spruces, and Douglas-fir. Less commonly, western conifer-seed bugs will feed on seeds and developing fruit of many trees and shrubs. Damage Western conifer-seed bug feeds largely on developing seeds within the cones of pines and other conifers. Injured seeds fail to develop normally, and seed production can be greatly reduced. The cones may also ooze sap from the feeding puncture wounds. In yards and gardens, western conifer-seed bugs will occasionally feed on developing seeds and fruit of many plants, and they can be one of a number of bugs (e.g., various stink bugs, leaffooted bugs, plant bugs, boxelder bugs) that create catfacing injuries to fruit. Western conifer-seed bug is most familiar as an increasingly encountered nuisance invader of homes in fall. It is essentially harmless and does not bite, although its rather bizarre appearance often causes alarm. This insect may also produce a slightly pine-scented odor when disturbed. Distribution Western conifer-seed bug is native to western North America; however, it has seen broad extensions of its range in recent decades. It is now commonly found throughout most of the midwestern and eastern U.S. Furthermore, it has also been accidentally introduced into Europe and is presently spreading through the continent. Appearance Western conifer-seed bug is a member of the leaffooted bug family Coreidae and has the typical feature of this family of long hind legs with a flattened area near the tip. Adults are about ¾ inch long, generally orange-brown, with some black markings on the back. Young nymphs are light orange but increasingly darken in later stages. Life History and Habits Winter is spent in the adult stage, under debris, loose bark, abandoned bird nests, or other protected sites, including areas behind building walls. Adults emerge during warm days in spring and feed on young cones and flowers. Mating occurs in spring, and shortly afterward, females begin to lay eggs. Eggs are laid in small masses, usually end-to-end, on needles or cones. Egg laying continues over several months, and one female may lay a total of 100–200 eggs. Eggs hatch in about 10 days and the nymphs feed on needles and developing seeds of the host plant. The nymphs develop through five instars, typically taking a little more than a month to complete. A second generation is likely produced in warmer areas, but one generation per year is normal in the northern parts of the range. Since egg laying is staggered and multiple generations can occur, all stages may be present on plants through much of the summer. As weather cools and day length shortens, adults move to overwintering sites and prepare to go into winter dormancy. During this time they may be active during warm periods, but reproduction is suspended and activity slows.

Related Species Twelve species of Leptoglossus occur north of Mexico, and several of these are associated with plant injuries. Leaffooted bug (L. phyllopus) is common in the eastern half of the U.S. and is also found in southern California. Its most common host in Florida is thistle, and in Kansas it is common on yucca. It may also occur on tender shoots, buds, and fruits of a wide variety of plants and incidentally damage some fruit and nut crops. L. clypealis is a western species, occasionally damaging to nut crops but usually associated with native plants such as yucca. Leaffooted pine seed bug (L. corculus) is commonly damaging to pine seeds, and L. fulvicornis can be common on magnolia fruit in the southeastern states. In California, L. zonatus is reported to damage fruit of pomegranate, pistachio, almonds, and tomatoes. 602

A

B

C D

A. Western conifer-seed bug.

E

DAVID SHETLAR

B. Eggs of western

conifer-seed bug.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Western conifer-seed

bug nymph.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

D. A leaffooted bug Leptoglossus phyllopus. DAVID CAPPAERT, BUGWOOD.ORG

E. Leaffooted bugs

feeding on fruit.

JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

F

G

F. Leaffooted bug nymphs. JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

G. A western species

of leaffooted bug, Leptoglossus clypealis. WHITNEY CRANSHAW

H. Nymphs of the

leaffooted bug Leptoglossus fulvicornis. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

I. Adult and last-instar nymph of the leaffooted bug Leptoglossus fulvicornis. LACY L. HYCHE, AUBURN UNIVERSITY, BUGWOOD.ORG

J. Catfacing of peach caused

by feeding injury produced by a leaffooted bug. CLEMSON UNIVERSITY–USDA COOPERATIVE EXTENSION SLIDE SERIES, BUGWOOD.ORG

H

I

J

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

scales and MealYBuGs assocIated wIth FruIt InJurIes Euthochtha galeator1 is another common leaffooted bug found feeding on buds, seeds, and terminal growth of various trees and shrubs in the eastern U.S. The feeding of squash bug (Anasa tristis)1 on fruits of squash produces sunken wounds that result in scabby areas on the surface and may provide entry wounds for decay organisms. The largest members of the leaffooted bug family in the U.S. are in the genera Acanthocephala and Mozena.1 None are pests of garden plants, but their large size can attract attention. Acanthocephala declivis is found over a wide area of the southeastern U.S., where it is associated with oak. Acanthocephala femorata, sometimes known as the “Florida leaffooted bug” is also found in the southern states but occurs in Texas and Mexico. It is sometimes damaging to citrus fruit and roses. Acanthocephala terminalis is the most northernranging member of the genus.

Scabby patches on squash fruit result from reaction to squash bug feeding wounds. WHITNEY CRANSHAW

1

Hemiptera: Coreidae

SCALES AND MEALYBUGS ASSOCIATED WITH FRUIT INJURIES A few types of armored scales will colonize the surface of developing fruit. This habit is best known with San Jose scale (Quadraspidiotus perniciosus),1 which can cause serious fruit blemishing to apple, pear, and plum. Surface pitting and a reddish ring often develop around the feeding site. California red scale (Aonidiella aurantii)1 and yellow scale (A. citrina) occur in California, where they can develop on the surface of citrus fruit. Some species of mealybug can damage fruit. Infestations of citrus mealybug (Planococcus citri)2 on stems can cause abortion of flowers and fruit as a result of toxins California red scale infested orange fruit. introduced with the saliva. In high populations they may also colonize fruit. Clusters JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA of developing grape can also be infested by grape mealybug (Pseudococcus STATEWIDE IPM PROGRAM maritimus)2 and obscure mealybug (P. viburni). A great many other insects associated with fruit crops, notably certain aphids, psyllids, soft scales, and mealybugs, can indirectly damage fruit through their excreted honeydew and the sooty molds that subsequently grow on honeydew-contaminated surfaces. 1

Hemiptera: Diaspididae; 2 Hemiptera: Pseudococcidae

604

B C

D A. The leaffooted bug Euthochtha galeator. JOHNNY N. DELL, BUGWOOD.ORG

B. Squash bug feeding

on pumpkin fruit. WHITNEY CRANSHAW

C. The leaffooted bug

Acanthocephala declivis. WHITNEY CRANSHAW

D. The leaffooted bug

Acanthocephala terminalis.

A E

DAVID SHETLAR

F

E. San Jose scale on apple. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

F. Close-up of San Jose scale. DAVID SHETLAR

G. California red scale. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

H. Citrus mealybug infesting orange fruit. JIM KALISCH, UNIVERSITY OF NEBRASKA

G H

I. Grape mealybugs infesting cluster of grapes. HAROLD J. LARSEN, COLORADO STATE UNIVERSITY

J. Sooty mold growing on

honeydew collected on surface of citrus fruit. DON FERRIN, LOUISIANA STATE UNIVERSITY AGRICULTURAL CENTER, BUGWOOD.ORG

I

J

Insects and MItes assocIated wIth Flowers, FruIts, nuts, and seeds

ERIOPHYID MITES THAT DAMAGE FRUITS AND FLOWERS Eriophyid mites are minute mites that can produce a range of plant disorders. Many produce various types of galls on leaves and buds, discussed on page 328. Others, known as rust mites (page 320), feed on the surface of leaves and needles, producing a bronzing of foliage. Injury to developing fruit and flowers is also produced by some eriophyid mites. Gross distortions of the male flowers of green ash are produced by the ash flowergall mite (Aceria fraxiniflora),1 causing the flowers to enlarge and persist on the trees, usually becoming noticeable after leaf fall. Similar distortions of flowers are produced on walnuts by A. neobeevori. Cottonwood catkingall mite (Eriophyes neoessigi)1 induces the catkins of various cottonwoods to grossly enlarge, in some cases to the size of a small cluster of grapes. Bud abortion and distortion of flowers can be produced by the camellia bud mite (Cosetacus camelliae),1 now widely distributed in the southeastern states and California. Blueberry bud mite (Acalitus vaccinii)1 deforms buds and berries of blueberry and huckleberry throughout much of the eastern U.S., particularly in the southeastern states. Redberry mite (A. essigi)1 damages cultivated and wild blackberries, producing irregular ripening in the form of hard red or green drupelets. Redberry mite is most common in the Pacific States, but known to occur in the Midwest. Dryberry mite (Phyllocoptes gracilis)1 develops on leaves, buds and fruit of raspberry, blackberry and loganberry. Injuries to fruit can resemble sunscald. Juniper berries are often heavily infested by juniper berry mite (Trisetacus quadrisetus)2 in western North America, causing seed to abnormally form. Several of the leaf-feeding rust mites also colonize fruit, producing a bronzing and roughening of the fruit skin known as “russeting.” Pear rust mite (Epitrimerus pyri)1 produces bronzing of both pear fruit and foliage. Apple rust mite (Aculus schlechtendali)1 produces similar injury to apple and is occasionally also found on pear. Citrus rust mite (Phyllocoptruta oleivora)1 occurs in all citrus-producing regions. On orange it produces a rust-colored symptom on the surface; symptoms on lemon are more silvery. Pink citrus rust mite (Aculops pelekassi)1 is the more damaging citrus-feeding rust mite in Florida, causing fruit russeting and leaf bronzing. Along the coastal areas of California, citrus bud mite (Eriophyes sheldoni)1 can be damaging, causing distortions of developing leaves and fruit. Acari: Eriophyidae; 2Acari: Phytoptidae

1

below left: Cottonwood catkin gall. WHITNEY CRANSHAW below: Irregular ripening of blackberry due to redberry mite. ART ANTONELLI, WASHINGTON STATE UNIVERSITY

606

A. Old ash flowergalls exposed after leaf drop. WHITNEY CRANSHAW

B. Ash flowergalls. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Damage by blueberry

bud mite.

JERRY A. PAYNE, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG

D. Pearleaf blister mite damage to leaves and fruit.

B

HAROLD J. LARSEN, COLORADO STATE UNIVERSITY

E. Skin russeting

by pear russet mite. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

F. Skin russeting produced by citrus rust mite. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

G. Damage to citrus

bud by citrus bud mite.

A

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

C D

F

G

E

CHAPTER EIGHT

NATURAL ENEMIES OF INSECTS AND POLLINATORS: THE “BENEFICIAL BUGS”

Entomologists often now use the term “services” to describe the beneficial roles that insects and related invertebrates perform in our environment. Activities of these organisms are normally unseen by the average observer, but they contribute to all aspects of a healthy garden ecosystem. Without the services of insect natural enemies, populations of pest species would go largely unchecked. Other insects—along with many mites, millipedes, sowbugs, and earthworms—are macrodecomposers that handle the large amount of dead plant matter, dead animals, and animal waste that is constantly being produced, preventing it from piling up and allowing the nutrients locked within to be released into the nutrient cycling system. Furthermore, a very large percentage of flowering plants, including most of our fruits and vegetables, are pollinated by a host of bees, flies, beetles, butterflies, moths, and other insects. There are several kinds of natural controls that work to regulate populations of all insects. Weather-related events, such as periods of extreme temperatures or heavy rainfall, can sometimes have enormous adverse effects on insects and mites. Many plants have some ability to fight off pests (host plant resistance), producing chemicals toxic to a feeding insect or stimulating physical defenses, such as a pitch flow that can entrap attacking insects. Physical features of some plants, such as hairs or a waxy surface, can also deter and prevent successful insect attack. Perhaps the most widely recognized of the natural controls, however, and most observable to the gardener, are the natural enemies of insects. Three primary groups of natural enemies predominate: predators, parasitoids, and pathogens, examples of which are described in the following section. Although these are constantly active under natural conditions, there are occasions when humans seek to enhance their activities to be more effective in suppressing a particular plant pest. This human intervention with natural enemies is then described as biological control. One way this can be done is to acquire a natural enemy through a commercial supplier; more than four dozen natural enemy species are commercially available. These might be introduced into a crop where they do not already exist, such as introducing a whitefly parasitoid for control of greenhouse whitefly, or to augment numbers of an existing natural enemy, such as when one distributes green lacewing eggs in a garden. The purchase and release of some insects is quite widely known in the gardening community, notably releasing adults of field-collected convergent lady beetles or placement of egg cases of the Chinese mantid in a garden. Although use of these “bugs for hire” is fairly popular, it is a far less efficient and effective biological control strategy than methods that conserve and enhance the existing natural enemies already present in a yard and garden. These involve purposeful efforts to improve the environment in ways that meet needs of the natural enemy species. For example, adult stages of many insect predators (e.g., lady beetles, green lacewings, flower flies, hunting wasps) sustain themselves on nectar and/or pollen. By purposefully planting the types of flowers that are used as nectar and pollen sources, their activities can be optimized. Diversification of plantings can improve the availability of different kinds of prey that can be used to sustain larval stages of insect predators. Some insects, notably certain hunting wasps (and many solitary bees), need nesting sites, which may be in the form of small holes or cavities in wood. Also, it is very important that any other insect control practices, such as use of insecticides, be done only in a manner that minimizes effects on natural enemy species, that is, that fully integrate natural controls with other management methods. 608

A, B. There are a great many natural enemies

of garden pests, including various insects such as (A) mantids, spiders such as a (b) jumping spider, predatory mites, and centipedes. WHITNEY CRANSHAW

A

C. Macrodecomposers such as earthworms

B

help recycle the nutrients present in dead plant and animal matter. WHITNEY CRANSHAW

D, E. Many plants are dependent on pollination by insects such as (d) bees, (e) butterflies, moths,

beetles, and flies. WHITNEY CRANSHAW

F. A few organisms that can provide biological control of other insects are commercially available, such as these field-collected convergent lady beetles. MATT CAMPER, COLORADO STATE UNIVERSITY

G, H. Adult stages of many insect natural enemies

C D

E

F

G H

sustain themselves on nectar or pollen or both, such as (g) flower flies and (h) hunting wasps. WHITNEY CRANSHAW

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES A great many kinds of insects—as well as all spiders and centipedes and many mites—develop as predators of insects or other arthropods. Arthropods that are predators are free-living hunters in their immature stages, actively seeking prey, and they consume many prey in the course of their development. Adult stages of insect predators may have similar habits, particularly those that have simple metamorphosis (e.g., mantids, predatory bugs) as well as spiders and predatory mites. Other kinds of insect predators switch diet in the adult stage to feed largely or exclusively on nectar, pollen, honeydew, and similar materials. The availability of these adult food sources allows them to survive longer and often to lay more eggs.

Lady Beetles (Ladybugs, Ladybird Beetles)1 Lady beetles are the most familiar and widely recognized predators of garden insects. Adults of the great majority have a characteristic round-oval shape, are brightly colored, and often have bold patterning on the wing covers. A pattern of black spots on an orange or reddish background is present on many of the most commonly encountered species, including convergent lady beetle (Hippodamia convergens), twospotted lady beetle (Adalia bipunctata), sevenspotted lady beetle (Coccinella septempunctata), and multicolored Asian lady beetle (Harmonia axyridis); however, other common lady beetles have variations of color and patterning, such as the parenthesis lady beetle (Hippodamia parenthesis), variegated lady beetle (H. variegata), pinkspotted lady beetle (Coleomegilla maculata), eyespotted lady beetle (Anatis mali), and twicestabbed lady beetle (Chilocorus stigmata). Many lady beetles may be uniformly colored, black or gray, and a few are striped. Many lady beetles are generalist predators that feed on many kinds of insects and mites, including aphids, small caterpillars or beetles, and insect eggs. Many of the most commonly observed species feed primarily on aphids, although other prey may be incidentally eaten, but other lady beetles are more specialized predators. For example, the twicestabbed lady beetle feeds only on armored scales, and the spider mite destroyers (Stethorus species) feed on mites. The larvae of all are strictly predators, but adults of most species also supplement their diet with pollen, nectar, and honeydew, and the presence of such foods around the yard or garden may be important in maintenance of these beneficial insects. When prey or alternate sources of nourishment are not available, adult lady beetles readily disperse to search other sites for food. Most lady beetles lay eggs in masses of 5–30 orange-yellow eggs. The eggs are quite distinctive, being round with pointed tips, although they can resemble those produced by some leaf beetles (Chrysomelidae family). Eggs are usually laid near colonies of insects that provide food for their larvae. The immature or larval stages look very different from the adult beetles and are often overlooked or misidentified. Lady beetle larvae are elongated, generally dark colored, and usually marked with orange, yellow, or purple, or combinations of these. Some species may have fleshy spines and a few that specialize on mealybugs and woolly aphids as prey are covered with white wax. Larvae are active hunters that can crawl rapidly over plants, searching for food. This very different appearance of the immature forms can sometimes be confusing to gardeners, who may even mistake them for pest insects—but the larval stage of the lady beetles is, by far, the most important stage in terms of preying on other insects, consuming far more than the adults.

610

A

B

C

D

E

F

A. Convergent lady beetle.

G H

WHITNEY CRANSHAW

B. Twospotted lady beetle. WHITNEY CRANSHAW

C. Sevenspotted lady beetle. WHITNEY CRANSHAW

D. Multicolored Asian

lady beetle.

WHITNEY CRANSHAW

E. Pinkspotted lady beetle. DAVID SHETLAR

F. Parenthesis lady beetle. WHITNEY CRANSHAW

G. Spider mite destroyer. WHITNEY CRANSHAW

H. Twicestabbed lady beetle. DAVID SHETLAR

I

J

I. Lady beetle egg mass. DAVID SHETLAR

J. Lady beetle egg mass

laid on tree trunk.

HAROLD J. LARSEN, COLORADO STATE UNIVERSITY

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PrEdators of iNsEcts aNd mitEs The larval stage of lady beetles is often completed in two or three weeks. They then seek out a place to pupate, which may be on leaves, trunks, sides of buildings or other solid surfaces. The pupa is attached to these objects at the base of the abdomen and during this period will not move, except to twitch sometimes when disturbed. The adult stage will typically emerge a week or two after the pupa is formed, and the pupae often become increasingly darker and more patterned as adult emergence approaches. Most lady beetles survive winter as an adult in sheltered locations, such as under leaves, behind bark flaps, and sometimes behind walls of buildings. Most lady beetles spend winter alone or in small groups, but in some areas of the country the convergent lady beetle migrates to higher elevations during its dormant periods and may aggregate in large numbers. These mass aggregations, particularly those that occur in the Sierra Nevada Mountains, serve as the source of adult lady beetles that are then sold through nursery and garden catalogs. Although the sale and release of these wild-caught convergent lady beetles has long been a common and popular practice, it has little value for a gardener since almost all the beetles immediately disperse from the area. Furthermore, the field-collected beetles are in a semidormant stage (diapause) and will normally not begin to lay eggs for several weeks following their release. Several lady beetles present in yards and gardens are not native to North America, notably the sevenspotted lady beetle and multicolored Asian lady beetle. The latter derives its name from having considerable variation in coloration and spotting. It is now often one of the most common lady beetles encountered in yards, gardens, and crop fields and a voracious predator of aphids. Unfortunately, the multicolored Asian lady beetle, unlike the native species, has a habit of entering buildings in late summer and early fall, sometimes creating serious nuisance problems. They are also capable of producing a mild nip. Several other specialist lady beetles have also been introduced into North America. Lindorus lophanthae, known as the “singular black lady beetle,” is commonly sold as a Convergent lady beetle (top to bottom) pupa, biological control of armored scales. This native of Australia is only about ⅛ inch in recent pupa that has not diameter, and the larvae can actually fit under the shells of scales. Cryptolaemus yet darkened, prepupa. WHITNEY CRANSHAW montrouzieri, known as the mealybug destroyer, is another commonly sold species used to manage citrus mealybug in citrus orchards, greenhouses, and interiorscapes. Perhaps the most famous lady beetle is the Vedalia beetle (Rodolia cardinalis), which was purposefully imported into California to control the cottony cushion scale on citrus trees in 1888. This introduction was spectacularly effective in eliminating cottony cushion scale as a serious pest, and it provided the first clear demonstration, worldwide, of the potential value of biological control for managing insects and mites. About 480 species of lady beetles can be found throughout North America and, with very few exceptions, all develop as predators of other insects and mites; in addition, there are seven North American species in the genus Psyllobora that feed on fungi, particularly powdery mildews. These are all considered beneficial inhabitants of the yard and garden. A notable exception are the “bad apples” of the lady beetle family: the Mexican bean beetle and squash beetle (page 204), which have a plant-feeding habit. 1

Coleoptera: Coccinellidae

612

A

B

C D

E

F G

A. Lady beetle larvae at egg hatch. WHITNEY CRANSHAW

B. Larva of the

convergent lady beetle. WHITNEY CRANSHAW

C. Larva of the

multicolored Asian lady beetle. WHITNEY CRANSHAW

H

I

D. Larva of the sevenspotted lady beetle. WHITNEY CRANSHAW

E. Massed convergent

lady beetles in overwintering site. JIM KALISCH, UNIVERSITY OF NEBRASKA

F. Larva of the mealybug destroyer lady beetle. DAVID CAPPAERT, BUGWOOD.ORG

G. Range of color

and patterning of multicolored Asian lady beetle, a species that enters buildings during the dormant season. DAVID SHETLAR

H. A vedalia beetle

next to a cottony cushion scale.

JACK KELLY CLARK COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

I. A Psylloborus species

of lady beetle that feeds on powdery mildew. WHITNEY CRANSHAW

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Ground Beetles1 Ground beetles are common insects of gardens. Most are broadly oval in form, with prominent forward-projecting jaws. They have hard wing covers that are typically dark, but they may have metallic coloration. Adults can be very active and fast moving, although they usually spend days under cover of leaf litter and other sheltering debris. Larvae are soft-bodied, elongate, and also predators. Larvae are usually active at the soil surface or tunnel in the upper soil. Almost all ground beetles develop as predators and may feed on a wide variety of insects, snails, and slugs. As their name may indicate, most restrict their activity to areas at or around the soil surface and are poor climbers; however, a few species may occur on plants, such as the large, striking Calosoma species, known as “caterpillar hunters,” that attack larvae of gypsy moth and other caterpillars. Bembidion ground beetles can be important predators of insect eggs on leaves. Some of the most common species belong to the genus Harpalus, which contains more than 400 species of beetles that range from iridescent green to shiny black. Poecilus is another large genus with typically green to bluegreen beetles. Bombardier beetles (like Brachinus spp.) are notable for their unique defensive ability, involving production of a noxious spray at near boiling temperature that they shoot from the tip of the abdomen. Somewhat atypical ground beetle forms occur with Scarites spp. These have the head and first section of the thorax (pronotum) joined tightly together and separated from the wings and abdomen by a narrowed constriction. A group of insects now commonly classified with the ground beetles are the tiger beetles. These are extremely active insects and most readily fly. Both adults and larvae are general predators of other insects, although larvae hunt primarily by ambush from soil tubes where they develop. Most tiger beetles are in the genus Cicindela. 1

Coleoptera: Carabidae

above left: Soil burrows of a tiger beetle. WHITNEY CRANSHAW

above: Tiger beetle, Cicindela punctulata. WHITNEY CRANSHAW

left: Larva of the tiger beetle Cicindela punctulata, extracted from burrow. WHITNEY CRANSHAW

A

B A. Harpalus species ground beetle.

C D

JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Harpalus affinis. DAVID SHETLAR

C. Amara apricana. DAVID SHETLAR

D. Calasoma

scrutator.

DAVID SHETLAR

E. A bombardier

beetle.

DAVID SHETLAR

F. Ground beetle larva feeding on cutworm. JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Ground beetle

larva.

DAVID SHETLAR

E

F

G

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Rove Beetles1 Rove beetles have an unusual appearance with a very elongate body and very short wing covers, which do not even extend to cover the abdomen. It is an extremely diverse and abundantly represented family of insects, considered by many the largest family of any animal or plant on earth, with more than 63,000 described species. Many develop as predators of insects and mites, particularly of insects found in soil. Other rove beetles are scavengers of carrion or feed on dung or fungi. Larvae of many rove beetles found in and around yards and gardens specialize in attacking fly maggots and puparia around compost piles and other sites with decomposing plant matter. Aleochara bilineata is Rove beetles feeding on maggot. an introduced species that has spread widely and is an important JIM KALISCH, UNIVERSITY OF NEBRASKA predator of root maggots. Rove beetles in the genus Platydracus are larger and known to attack cutworm and armyworm larvae. When exposed, these beetles have a habit of curling the abdomen upward and over the body, in a somewhat threatening manner. The tiny Oligota oviformis is sometimes called the “spider mite destroyer” as the larvae and adults feed on spider mites that attack fruits and ornamental plants in the garden. The greenhouse rove beetle Dalotia (=Atheta) coriaria is a small black species commonly sold for control of fungus gnat larvae. These are most useful in greenhouses, enclosed environments, and gardens that have suitable hiding places and moisture. 1

Coleoptera: Staphylinidae

A Cantharis species of soldier beetle. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Soldier Beetles1 Soldier beetles are elongate beetles with fairly soft wing covers, lending them the alternate name “leather-winged beetles.” Adults are usually patterned with yellow or orange and black markings. Soldier beetles are most commonly observed on yellow flowers late in the season, feeding on pollen and often in copula. Some (Cantharis and Podabrus species) can be important predators of aphids, mealybugs, and other soft-bodied insects. The rarely noticed larval stages are elongate and covered with a velvet-like integument. They develop in the soil where they feed on other arthropods, but they occasionally invade homes in search of food. Larvae of the common Pennsylvania leatherwing (Chauliognathus pensylvanicus) are reported to develop as predators of root maggots in soil. 1

Coleoptera: Cantharidae

616

B

A

C

D

E

F

G

A. Rove beetle. WHITNEY CRANSHAW

B. Rove beetle. WHITNEY CRANSHAW

C. Rove beetle. DAVID SHETLAR

D, Rove beetle larva. DAVID SHETLAR

E. A Podabrus species

of soldier beetle.

JIM KALISCH, UNIVERSITY O F NEBRASKA

F. Soldier beetle larva. DAVID SHETLAR

G. Pennsylvania leatherwing. DAVID CAPPAERT, BUGWOOD.ORG

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Blister Beetles1 Blister beetles can have many kinds of associations with a garden. The adults are plant feeders, with many common at flowers feeding on pollen (page 566) and a few occasional plant pests that chew leaves of various legumes, clematis, and other garden plants (page 206). The larval stages develop as predators of various insects. Those in the genus Epicauta feed on the eggs of grasshoppers, and their abundance often cycles with the numbers of their prey. The brightly colored Lytta species and large flightless “oil beetles” (Meloe spp.) develop while feeding on the food and larvae of developing bees and wasps that nest in the ground. 1

Blister beetle larva.

Coleoptera: Meloidae

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Fireflies/Lightningbugs1 Despite their common names, fireflies or lightningbugs are neither flies nor bugs, but instead are a type of beetle. Like soldier beetles and blister beetles, fireflies have fairly soft wing covers and are elongate in form. The head is usually hidden below a flap of the first thoracic segment and many species (but not all) have light organs on the tip of the abdomen used to flash mating signals. Larvae of fireflies are usually found in moist sites, where they feed on soft invertebrates such as slugs, snails, and earthworms. They are much more abundant east of the Great Plains than in western states, and species that produce light are particularly uncommon in western North America. Adults of some fireflies may also be predatory, feeding on scale crawlers, aphids, and similar small, soft-bodied insects. 1

Coleoptera: Lampyridae

Soft-winged Flower Beetles1 Soft-winged flower beetles are moderate-sized beetles (1⁄5 to ⅓ inch), usually bluish-black with red or orange markings. They are typically observed on flowers, where they may feed on pollen, but some are also predatory and will feed on insect larvae, aphids, and other small, soft-bodied insects. They can be common in fields but are infrequently found in gardens, and members of the genus Collops are considered important predators of insects in many crops, particularly in the western states. Larvae also develop as predators but live in the soil and are rarely observed. 1

Coleoptera: Melyridae

618

B C

A D

E

A. Blister beetle. WHITNEY CRANSHAW

B. A first-instar larva of a blister beetle

(triungulin).

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. A nocturnal, luminescent firefly,

Photinus pyralis.

JIM KALISCH, UNIVERSITY OF NEBRASKA

D. A day-active, non-luminescent firefly,

F

Ellychnia corrusca.

DAVID CAPPAERT, BUGWOOD.ORG

E. Larva of a firefly. DAVID SHETLAR

F. Larva of a firefly. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

G. Collops beetle feeding on weevil larva. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

G

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Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Clerid Beetles1 Clerid beetles, or checkered beetles, are usually brightly colored insects that are generally elongate in form and somewhat flattened. Most species are important predators, as adults and larvae, of bark beetles and other woodboring beetles. The adult beetles are commonly found inspecting the trunks of dead trees or logs, where they are searching for food or egg-laying sites. The adults also frequently visit flowers. The immature clerid beetles are commonly found in tunnels of bark beetles. 1

Coleoptera: Cleridae

Cybocephalid Beetles1 The cybocephalids are relatives of sap beetles, but they have a predatory habit. Most are specialists of armored scales, but some feed on adelgids, mealybugs, and mites. The adult beetles are small, elongate-oval in shape, and either black or bicolored. The larvae look somewhat like small lady beetle larvae. Cybocephalus nipponicus has been introduced into the eastern U.S. to control the hemlock elongate scale, and in Florida to control the cycad scale. Native species in this genus also feed on armored scales. 1

Coleoptera: Cybocephalidae

Green Lacewings1 Several species of green lacewings commonly frequent yards and gardens, most in the genera Chrysopa or Chrysoperla. Adults are generally pale green insects with clear, highly veined wings they hold over the body when at rest. Some species turn a light brown during cold weather. They are delicate and very attractive insects that feed primarily on nectar, pollen, and honeydew, although adults in the genus Chrysopa also feed on small insects. The females lay a distinctive stalked egg, approximately ½ inch in height. Eggs may be laid in small groups or singly on leaves of plants throughout the yard. Lacewing larvae emerge from the egg in about a week. These larvae, sometimes called “aphid lions,” are voracious predators capable of feeding on a wide range of insects, including small caterpillars and beetles as well as aphids and other insects. They are perhaps best marked by their large sickle-shaped jaws that project from the head. The body is elongate, usually a bit thicker in the middle, and most lacewing larvae are some shade of light brown to nearly white. However, these features are obscured by the larvae of some “trash-carrying” species that pile the carcasses of prey, small bits of lichen, and other debris on their body, an effective camouflage from some predators that also allows them to escape detection by aphid-tending ants. Pupation occurs in a nearly spherical, pale-colored cocoon often attached loosely to leaves or needles. Some Chrysoperla species are produced commercially in insectary facilities. These are sold, often as eggs, for use in biological control of aphids and caterpillars in certain vegetable and greenhouse crops and interiorscapes. 1

Neuroptera: Chrysopidae

620

A

C

D

F B E

G H

A. Checkered beetle feeding on bark beetle. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

I

B. Checkered beetle feeding on emerald ash borer. DAVID CAPPAERT, BUGWOOD.ORG

C. Larva of a checkered beetle. WHITNEY CRANSHAW

D. A cybocephalid feeding

on hemlock scales. DAVID SHETLAR

E. Green lacewing eggs. DAVID CAPPAERT, BUGWOOD.ORG

F. Green lacewing adult. WHITNEY CRANSHAW

G. Green lacewing adult. DAVID SHETLAR

J

K

H. Green lacewing larvae

shortly after egg hatch. WHITNEY CRANSHAW

I. Late-instar larva of a green lacewing. DAVID SHETLAR

J. A “trash-carrying” larva

of a green lacewing.

SUSAN ELLIS, BUGWOOD.ORG

K. Cocoon surrounding

green lacewing pupa. WHITNEY CRANSHAW

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Brown Lacewings1 The brown lacewings are related to the green lacewings with generally similar habits, being predators of insects as both adults and larvae. Many are more specialized predators, feeding primarily on woolly aphids, mealybugs, scales, and mites, and they are usually associated with dense vegetation, including trees and shrubs. Adult brown lacewings are generally smaller than green lacewings, possess light brown wings, and are predators. Larvae are also predators, with a body generally similar to green lacewings but with mouthparts that are a bit less curved and a narrower body form. The eggs of brown lacewings are laid singly on foliage and do not have a stalk. 1

Neuroptera: Hemerobiidae

Dustywings1 Dustywings are very small insects (ca. ⅛ inch) that develop as predators of mites, but they may also feed on aphids, scale insects, and other small arthropods. The body of the adult insect is covered with fine powdery white wax; larvae are plump with short, projecting mandibles. Although easily overlooked, dustywings may be abundant on the trees and shrubs they frequent, especially conifers. 1

Neuroptera: Coniopterygidae

Dustywing larva. DAVID SHETLAR

Antlions1 The larvae of antlions are predators that establish cone-shaped pits in loose soil to trap insects that wander into the pit traps. Sometimes known as “doodlebugs,” the larvae have a generally oval body with prominently projecting elongate jaws (mandibles). They are ambush hunters that lie in wait, buried at the base of the pit, for passing prey. The adults are rarely noticed since they fly at night. The adults drop eggs onto dry soil, and upon hatching, the larvae scoot backwards in a spiral while flipping out fine soil or sand. This eventually forms a pit with steeply sloping sides. Any insect that drops into the pit is quickly grabbed by the jaws and pulled down into the soil where the body fluids are sucked out. Antlions are likely not major predators in landscapes, but interesting curiosities. 1

Neuroptera: Myrmelionidae

622

A

B

C D

E A. Brown lacewing.

WHITNEY CRANSHAW

B. Brown lacewing larva.

F. Antlion larva.

DAVID SHETLAR

DAVID SHETLAR

C. Brown lacewing larva feeding

G. Antlion larva feeding on cricket.

F on aphid.

DAVID CAPPAERT, BUGWOOD.ORG

D. Dustywing. DAVID SHETLAR

G

H

E. Antlion adult.

DAVID SHETLAR

JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Pits produced by antlion larvae. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Syrphid Flies (Flower Flies, Hover Flies)1 Syrphid flies are common, brightly colored flies most often seen at flowers, where they feed on nectar. Adults are typically marked with yellow or orange and black in a manner that can closely mimic certain bees or wasps; however, syrphid flies are incapable of biting or stinging and are harmless to humans. It is the larval stage of the syrphid fly that is an insect predator. Variously colored, the tapered maggots crawl over plants, and a single maggot can tear through dozens of aphids in a day. Syrphid fly larvae are particularly important in controlling aphid infestations early and late in the season, when many other predators are not active, and their body form also allows them to enter tightly curled leaves where aphids hide. Despite being common and abundant, the larvae are infrequently noticed as they are slow moving and often blend well with the plants. Indirect evidence of their prior activity is sometimes present on plants in the form of a tarry smear of excrement they leave behind after feeding on aphid prey. Although most syrphid flies seen in gardens develop as predators of insects, others have different habits. A few species of syrphid flies, known as bulb flies (page 502), develop by feeding on and tunneling plant tissues. Also common may be drone flies (Eristalis species), excellent mimics of honey bees. In their larval form—known as a rattailed maggot because of the very long breathing tube that extends from the end of the abdomen— drone flies develop in very moist soil or polluted water. 1

Diptera: Syrphidae

Predatory Midges1 Although most insects of the gall midge family Cecidomyiidae feed on plants and many produce galls or other plant distortions, a few are predators of other insects. The larvae are tiny maggots (ca. 1⁄10 inch), often orange or yellowish and found on leaves among colonies of their prey. The most common species encountered in gardens is Aphidoletes aphidimyza, a predator of aphids, and Feltiella acarisuga, a predator of spider mites. Both of these are also commercially reared and sold for control of greenhouse pests. 1

Diptera: Cecidomyiidae

624

A

B

C

D

E

A. Syrphid fly at flower. DAVID SHETLAR

B. Syrphid fly,

Helophilus species. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Syrphid fly, Toxomerus

species.

JONATHAN YOUSCHOCK

D. Syrphid fly laying egg

in aphid colony. DAVID SHETLAR

E. Syrphid fly egg. DAVID SHETLAR

F

F. Syrphid fly larva.

G

DAVID SHETLAR

G. Drone fly (top) and

honey bee (bottom). WHITNEY CRANSHAW

H. Syrphid fly larva. JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Larva of a drone fly, a rattailed

maggot.

JIM KALISCH, UNIVERSITY OF NEBRASKA

J. Spider mite predator midge,

Feltiella acarisuga. WHITNEY CRANSHAW

K. Aphid predator midge,

H

Aphidoletes aphidimyza.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

K

I

J

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Longlegged and Dance Flies The long-legged flies1 are moderately small flies noted for their metallic coloration. Species of Condylostylus are common across North America, with all species being metallic green, blue, or copper. Less noticed are species of Gymnopternus and Xanthochorus, which are yellow or brown with darker markings. Adult stages of both flies have prominent eyes and long legs. Adults feed on small insects such as gnats and midges. Larvae are also predaceous and some (Medetera species) live under bark and feed on bark beetle larvae. Dance flies2 are closely related to longlegged flies but lack the metallic coloration, and most are brown, gray, or black. Dance flies are most commonly observed perched on plant leaves, where they are looking for potential prey to fly by. When approached, these flies often run back and forth on leaf surfaces, quickly moving from one leaf to another. The longtailed dance fly, Rhamphomyia longicauda, is a woodland species that is easy to spot because of its large red eyes and feather-shaped bristles that line the legs. It can occasionally be found in shaded garden locations. 1

Diptera: Dolichopodidae; 2 Diptera: Empididae

Robber Flies1 Along with dragonflies, the robber flies are often the top predators of the airways over a field or garden. Robber flies vary considerably in size, but many are fairly large and almost all have a characteristically elongated abdomen. They have large eyes, used to scan the area where they perch, and a sharp beaklike mouthpart, hidden within a “mustache” of hairs. The adults are active fliers that will dart after any other insect that flies by, which they grasp with their front legs and rapidly paralyze with a bite. They are generalist predators and will attempt to attack almost any insect of sufficient size to attract their interest. The larvae live in moist soil or decaying logs, where they also prey on other soft-bodied insects. Members in the subfamily Asilinae are often called giant robber flies, and species of Machimus and Proctacanthus can be found in most landscapes. Adults can range from 1 to 2 inches in length. On the other extreme, members of the subfamily Stenopogoninae are usually ½ inch or less in length, and most have yellow and black markings that mimic local wasps. The thinnest of the robber flies are species in the subfamily Leptogastrinae that can actually mimic crane flies. Species of Leptogaster are often seen perched on the top of a plant holding their abdomen straight out from the plant. Species in the subfamily Laphriinae are medium to large flies, and most have hairy bodies that mimic bees. Species of Laphria can look so much like bumble bees that most people simply walk by them. 1

Diptera: Asilidae

626

A

B

C

D

E

F

G

A. Longlegged fly feeding on leafhopper. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Longlegged fly feeding on small fly. DAVID SHETLAR

C. Dance fly. DAVID SHETLAR

D. Dance fly, Rhamphomyia longicauda. DAVID SHETLAR

E. Robber fly feeding on cabbage butterfly. WHITNEY CRANSHAW

F. Robber fly feeding on honey bee. WHITNEY CRANSHAW

G. Robber fly adult emerging from pupal case. WHITNEY CRANSHAW

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Bee Flies1 Bee flies are typically moderate-sized flies with a rounded body often covered with hairs, giving them a superficial resemblance to a bee. The wings often have brown or black markings, and many have elongated mouthparts used to suck nectar from flowers, their main food. The larvae develop as predators or external parasites of other insects. Many bee flies develop on host larvae of ground-nesting bees, but others develop on grasshopper eggs and the larvae and pupae of beetles, moths, flies, and wasps. They range widely in size, with the largest, Xenox spp., being parasites of carpenter bee larvae. 1

Diptera: Bombyliidae

Predatory Thrips1 Adults of the predatory thrips1 are usually dark colored and often conspicuously marked with black-and-white banding, lending them the alternative name “bandedwinged thrips.” Most feed primarily on smaller prey, notably spider mites and plant feeding thrips, Predatory thrips, Franklinothrips but they may take other prey and supplement their diet with pollen. Most occur in the genus vespiformis. Aeolothrips, which has 31 North American species, but other predatory thrips that may be WHITNEY CRANSHAW locally common include Franklinothrips vespiformis,1 with a body form that mimics ants, and Leptothrips mali (black hunter thrips),2 the most important predatory thrips in eastern orchards. A species sold for biological control is the sixspotted thrips (Scolothrips sexmaculatus),3 used to control spider mites. 1

Thysanoptera: Aeolothripidae; 2 Thysanoptera: Phlaeothripidae; 3 Thysanoptera: Thripidae

Predatory Stink Bugs1 Although stink bugs include many species that feed on plants (pages 300 and 594–596), some are predators. All stink bugs are characterized by their distinctive shieldlike body and ability to produce an unpleasant odor when disturbed. Those that feed on insects are capable of subduing large prey, such as caterpillars or beetle larvae, which they impale with piercing-sucking mouthparts. Among the predatory stink bugs commonly found in gardens are the twospotted stink bug (Perillus bioculatus) and related Perillus species, which specialize in beetle larvae and the spined soldier bug (Podisus maculiventris) and related Podisus spp., which feed primarily on caterpillars. A particularly colorful species found in the southeastern states is the Florida predatory stink bug (Euthyrhynchus floridanus).  Immature stages of most predatory stink bugs, which lack fully developed wings, are generally rounded in body form and may have colorful patterning. Most stink bugs feed on plants and are discussed in other sections. Those that are predatory can be distinguished from the plant feeding stink bugs by viewing the attachment of the mouthparts at the front of the head. The mouthparts of predatory species are attached only at the tip, allowing them to project forward when stalking prey. Mouthparts of plant-feeding stink bugs are attached more extensively to the head and can only be directed downward. 1

Hemiptera: Pentatomidae

628

A

B

A. Bee fly, Systoechus species. WHITNEY CRANSHAW

B. Bee fly, Villa species. WHITNEY CRANSHAW

C. Sixspotted thrips.

C D E

F

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

D. Predatory thrips, Aeolothrips species. WHITNEY CRANSHAW

E. Spined soldier

bug nymph feeding on caterpillar. RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

F. Spined soldier bug. DAVID SHETLAR

G. Spined soldier

bug eggs.

DAVID SHETLAR

G

H. Florida predatory bug. JOHNNY N. DELL, BUGWOOD.ORG

H. Twospotted stink bug

feeding on Colorado potato beetle larva.

JOHN CAPINERA, UNIVERSITY OF FLORIDA

H

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Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Assassin Bugs1 Assassin bugs are moderately large insects that can also feed on fairly large prey, such as insect larvae. Most assassin bugs are elongate in form, have a pronounced “snout” on the front that is the base for the stylet mouthparts, and are spiny. Despite their prodigious ability to dispatch most garden pests, they rarely become very abundant, since they in turn succumb to many natural enemies of their own, including fellow assassin bugs. Common assassin bugs associated with gardens include the spined assassin bug (Sinea diadema) and related Sinea spp., the bee hunters (Apiomerus spp.), and several elongate assassin bugs in the genus Zelus. Of even more dramatically slender form are the thread-legged bugs (Emesaya species), which have grasping front legs and can be mistaken for very thin mantids. The thread-legged bugs often feed on spiders and are able to move among spider webs. One of the largest assassin bugs is the wheel bug (Arilus cristatus), which can reach nearly 2 inches in length. They are an overall dark gray color and the pronotum behind the head has a series of distinctive, upright spines that look like the spokes of a above: Zelus luridus nymph wheel. This is a generalist predator that will feed on anything it feeding on hunting wasp. can capture. The eggs of this species are often found as a mass of WHITNEY CRANSHAW barrel-shaped eggs glued together in a flat mass with a dark below: Ambush bug feeding on honey bee. DAVID SHETLAR resinlike material. The nymph has a red, bulbous abdomen. Late in the season, ambush bugs (Phymata species) are commonly found on flowers. These are rather heavy-bodied assassin bugs with thick forelegs they use to capture flies, bees, and other insects that visit flowers. Their patterning and coloration blend well with the flowers on which they hide. All assassin bugs of sufficient size can bite humans if handled. The bite is often quite painful but of short duration and not a medical threat. 1

Hemiptera: Reduviidae

Damsel Bugs1 Damsel bugs are considerably smaller than assassin bugs (ca. ¼ inch) and usually dark yellow to pale brown or mottled gray. Similar to the assassin bugs, the forelegs are slightly thickened to assist in holding prey. Damsel bugs develop as general predators of insect larvae, small soft-bodied insects, and insect eggs. They are most common in grassy fields. 1

Hemiptera: Nabidae

630

A B

C D

A. Mating pair of the spined assassin bug. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Wheel bug. DAVID LEATHERMAN

C. Zelus luridus. WHITNEY CRANSHAW

D. Egg mass of the

assassin bug Zelus luridus and nymph. WHITNEY CRANSHAW

E. Threadlegged

E

bug.

F

DAVID SHETLAR

G

F. Ambush bug

eggs and newly hatched nymph. WHITNEY CRANSHAW

G. Damsel bug. WHITNEY CRANSHAW

H. Damsel bug

nymph.

BRADLEY HIGBEE, ARAMOUNT FARMING, BUGWOOD.ORG

H

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Predatory Plant Bugs1 The plant bug family includes several important species that can be seriously damaging to plants, such as the tarnished plant bug (page 592), fourlined plant bug, and honeylocust plant bug (page 296); however, many plant bugs are omnivorous and frequently feed on insects as well as plants. A few, notably in the genus Deraeocoris, are primarily predaceous and on some plants may be among the most important biological controls of spider mites, gall midges, and other pests of shade trees. 1

Hemiptera: Miridae

Big-eyed Bugs1 Big-eyed bugs are common predators in gardens, lawns, and field crops. Adults of most are gray, black, or tan in color and about ⅛ inch long; the wingless nymphs have a lighter-colored body. Similar in general appearance to many small seed or plant bugs, the big-eyed bugs are distinguished by having very large eyes along the sides of the head. They are active insects, and both nymphs and adults may be seen rapidly running in search of small insects, mites, or insect eggs. Almost all big-eyed bugs are in the genus Geocoris, with G. pallens and G. punctipes two of the common gray-colored representatives and G. uliginosus a common generally black species. 1

Big-eyed bug feeding on leafhopper.

Hemiptera: Geocoridae

RUSS OTTENS, UNIVERSITY OF GEORGIA, BUGWOOD.ORG

Minute Pirate Bugs1 The smallest of the predatory “true” bugs commonly found in yards and gardens (typically about 1⁄16 inch), minute pirate bugs feed on smaller arthropods such as spider mites, thrips, aphids, and insect eggs. The adults in the genus Orius are distinctive with black-and-white markings; Xylocoris spp. tend to be more uniformly colored dark gray or brown. Immature forms of minute pirate bugs are generally red or straw-colored and may superficially resemble a highly active aphid. Minute pirate bugs are most often seen in and around flowers, where they feed on thrips or, in the absence of prey, pollen and nectar. 1

Hemiptera: Anthocoridae

632

A

B

C D

E

F

A. Predatory plant bug Deraeocoris brevis. BRADLEY HIGBEE, PARAMOUNT FARMING, BUGWOOD.ORG

B. Nymph of the predatory plant bug Deraeocoris brevis. BRADLEY HIGBEE, PARAMOUNT FARMING, BUGWOOD.ORG

C. Big-eyed bug nymph feeding on chinch bug. DAVID SHETLAR

D. Minute pirate bug, Orius species. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

E. Nymph of a minute pirate bug, Orius species. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

F. Minute pirate bug, Anthocoris species. BRADLEY HIGBEE, PARAMOUNT FARMING, BUGWOOD.ORG

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Mantids1 Mantids are familiar insects to gardeners. Large and statuesque, all develop as predators of other insects, which they capture with their distinct grasping forelegs. Mantids develop from eggs that are laid in masses (an ootheca) covered with a protective layer of dried foam, giving them somewhat the appearance of a packing peanut. Immature forms resemble the adults but lack wings. The most common mantid in much of the northern U.S. is the introduced European mantid (Mantis religiosa), also known as the “praying mantid.” Both brown and green forms occur, the variation in large part related to the general color of the background vegetation where they develop, with brown forms predominating from drier sites. A bull’s-eye marking on the inside of the foreleg is a characteristic that can be used to distinguish this species. Of generally similar size are several native mantids in the genus Stagmomantis. These can also be variable in color, and in females the wings do not completely cover the end of the abdomen. Carolina mantid (S. carolina) occurs over a broad area east of Rockies extending into Florida. California mantid (S. above: European mantid making warning display. californica) and S. limbata occur in the southwestern states, and WHITNEY CRANSHAW the larger Florida mantid (S. floridensis) is native to Florida. below: European mantid nymph recently hatched. Perhaps the most familiar mantid to many gardeners is the WHITNEY CRANSHAW Chinese mantid (Tenodera aridifolia sinensis), which has been widely distributed through sales of egg masses by garden centers and nursery catalogs. The Chinese mantid is a very large species that is generally brown with green-and-yellow striping along the sides of the wings. More recently, another non-native species related to the Chinese mantid, known as the “narrowwinged mantid” (Tenodera angustipennis), has become established in areas of the Mid-Atlantic States. Most gardeners welcome the presence of mantids, and they are fascinating to watch; however, their ability to effectively control pests is usually far overstated. Being large and indiscriminate predators, they are too large to feed on small insects like mites, scales, and aphids. Often they hunt near flowers where they will capture bees, wasps, and other desirable species. Because of this, purchasing and distributing mantid egg cases in gardens is not recommended as a useful biological control of pests, although the practice can provide other pleasures to a gardener by increasing the very presence of mantids. (Note: It is a common myth in some areas of the U.S. that mantids are protected by law. This is without foundation, although they are the State Insect of Connecticut and South Carolina.) 1

Mantodea: Mantidae

634

A

B c

D E F

G A. European mantid mating pair. WHITNEY CRANSHAW

B. Egg cases produced by European mantid. WHITNEY CRANSHAW

C. Carolina mantid male. DAVID SHETLAR

D. Carolina mantid female. DAVID SHETLAR

E. Nymph of a Carolina mantid. DAVID SHETLAR

F. Chinese mantid. DAVID SHETLAR

G. Egg case of a Chinese mantid. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Earwigs1 Although the European earwig (page 52)1 is often considered a plant pest as well as a common nuisance, it is an omnivore that feeds on a wide variety of materials, including many insects. Other earwigs are primarily predaceous, however, including ringlegged earwig (Euborellia annulipes)2 and the spine-tailed earwigs (Doru species).3 1

Dermaptera: Forficulidae; 2 Dermaptera: Anisolabididae; 3 Dermaptera: Labiduridae

Dragonflies1 and Damselflies2 Dragonflies and damselflies are among the most widely recognized of the insect predators, and adults often move into yards and gardens. The adults are day-flying aerial hunters, capturing flying insects on the wing. Small flies make up much of their diet, including the occasional mosquito, but they may also catch larger prey, such as butterflies, large flies, and bees. Often they are most commonly observed to feed at dusk, when mating swarms of midges and gnats provide rich hunting. Immature dragonfly. Unlike the other natural enemies of insects found in yards, DAVID SHETLAR the immature stages of dragonflies and damselflies develop in water, with permanent ponds that have vegetation being particularly good breeding sites. These are top-level predators of these aquatic sites, either lying in wait as ambush hunters or slowly stalking prey. They feed mostly on a mixture of insects and crustaceans, sometimes taking tadpoles and small fish, which they grab with unique mouthparts, an extensible “lower jaw” (labium). 1

Odonata (suborder Anisoptera); 2 Odonata (suborder Zygoptera)

Crab Spiders1 Crab spiders are usually distinguished by the front two pairs of legs being particularly elongated. Most have a fairly bulbous abdomen and all hunt primarily by ambush, waiting on leaves and flowers for prey to approach. The “flower crab spiders” hunt at flowers, capturing flower visitors such as flies, bees, wasps, and the occasional moth or butterfly. They are variously patterned in yellows or white to blend in well with their background. Misumena vatia and Misumenoides formosipes are the two most common flower crab spiders; these are quite similar but the latter can usually be distinguished by the presence of dark markings. There are also 18 North American Mecaphasa spp., which are hairier than the other flower crab spiders. Less commonly observed are the “bark crab spiders,” which have a flatter abdomen and are marked with grays or browns to blend in well with bark, where they typically hunt. The most common species of bark crab spiders occur in the genera Xystichus and Bassaniana. 1

Araneae: Thomisidae

636

A

B

C D

F

E

G

H

A. European earwig. DAVID SHETLAR

B. Ringlegged earwig. DAVID SHETLAR

C. A Doru species of earwig. DAVID SHETLAR

D. Adult of the calico pennant, a skimmer type of dragonfly. DAVID SHETLAR

E. Mating pair of bluet damselflies. DAVID SHETLAR

F. Misumena vatia crab spider at blossom. WHITNEY CRANSHAW

G. Bark crab spider, Xystichus species. WHITNEY CRANSHAW

H. Crab spider, Misumenoides formosipes. DAVID CAPPAERT, BUGWOOD.ORG

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Jumping Spiders1 The jumping spiders are some of the most active hunters, and as their name indicates, they are capable of short (usually less than 1 inch) jumps. Most are brightly colored, and they have large eyes that allow them to track prey well. Among those with the brightest patterning are Phidippus species; the bold jumper (P. audax) is one particularly common in yards and gardens. Other common jumping spiders include various Salticus spp., such as the zebra jumper (S. scenicus), and the more muted-colored Platycryptus spp. 1

Araneae: Salticidae

Wolf Spiders1 Wolf spiders are active hunters that search the ground for prey, which they run down and subdue. Some species will dig ground burrow, lined with silk, and forage the general vicinity of the burrow, often at night. Others may be active both day and night and range more widely while hunting. Most wolf spiders are gray, brown, or nearly black, and some have lighter chevron or striping patterns that can be useful in identifications. Females are longer and more heavy-bodied than males, although legs of the latter are often proportionately longer. A distinctive habit of the females is that they carry their egg sac attached to the spinnerets at the end of the body. (Nursery web spiders also carry their egg sac, but with their jaws.) When the eggs hatch, the mother will tear open the sac and then carry the spiderlings on her back, where they remain for days, until the next molt. Size of wolf spiders ranges widely. Some of the smaller species are in the genera Pirata and Paradosa, which typically have a body length of ¼ to ½ inch. Among the commonly noticed wolf spiders in eastern North America that is somewhat larger is Rabidosa rabida (rabid garden spider), and some very large wolf spiders occur in the genera Tigrosa and Hogna. Hogna carolinensis (Carolina wolf spider) is generally considered the largest wolf spider in North America, with the body of the females sometimes reaching almost 1½ inches, causing it to be mistaken sometimes for a tarantula—or a small mouse. None of the wolf spiders are dangerous to humans, and they will readily attempt to flee if disturbed. 1

Araneae: Lycosidae

Nursery Web Spiders1 These spiders are often confused with wolf spiders. Most remain motionless while hiding among leaves or on tree bark. Their name comes from their habit of webbing together some plant leaves in which an egg case is deposited. The female spider often guards this “nursery” until the newly hatched spiderlings are able to start looking for their own food. Two large species often cause alarm in gardens. The forest nursery web spider, Dolomedes tenebrosus, often has a 3- to 4-inch leg span. The six-spotted fishing spider, D. triton, can reach 3 inches in leg span and occasionally visits backyard water features. 1

Araneae: Pisauridae

638

A. Bold jumper feeding on fly. WHITNEY CRANSHAW

B. Platycryptus species of

jumping spider.

JIM KALISCH, UNIVERSITY OF NEBRASKA

A

C. Zebra jumper.

B

WHITNEY CRANSHAW

D. Wolf spider.

C D

DAVID SHETLAR

E. Wolf spider carrying egg sac. WHITNEY CRANSHAW

F. Wolf spider female

carrying spiderlings. DAVID SHETLAR

G. Carolina wolf spider

near burrow.

JIM KALISCH, UNIVERSITY OF NEBRASKA

H. Nurseryweb spider. JIM KALISCH, UNIVERSITY OF NEBRASKA

I. Nurseryweb spider

carrying egg sac. DAVID SHETLAR

E

F

G H

I

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Dysderid Spiders1 The dysderid spider, Dysdera crocata, is a European species now widely distributed in North America and found in sites that harbor its primary prey, sowbugs and pillbugs. These “wood louse hunters” or “roly-poly hunters” possess very large jaws which, combined with their reddish coloration, often attract attention; they are harmless. Dysdera crocata will often enter homes through openings near ground level, and it may establish in damp basements for awhile if its sowbug prey is also present. 1

Araneae: Dysderidae

Barn orbweaver. TOM MURRAY

Orbweavers1

The orbweaver spiders are well recognized as the masters of web spinning, with many producing beautifully patterned concentric webs in late summer and early fall. The largest of these are the “garden spiders” (Argiope spp.) that can build large, very strong webs among shrubs and tall grasses that are capable of holding grasshoppers and other large prey. The garden spiders typically mark the center of the web with bands of reflective silk, often in a zigzag pattern, known as a stabilimentum. In most of eastern North America, the black-and-yellow garden spider (A. aurantia) predominates. In the drier areas of the west the banded garden spider (A. trifasciata) is most common, while in the southeast one finds the Florida garden spider (A. florida). All of these have a 1-year life cycle and mature in late summer and early fall. In some of the most southern areas of Florida, Texas, and California, a spring-maturing species, the silver garden spider (A. argentata), is present. In the southeast the golden silk spider (Nephila clavipes) attracts attention with the large webs it produces, often more than 3 feet in diameter, in open areas among trees and large shrubs. The furrow spider (Larinioides cornuta) is a very common, but smaller orbweaver found in urban gardens. It often prefers to build nests under the eaves of buildings and around night lights. It usually weaves a new nest every night and hides in nearby crevices during the day. Large orb webs are also produced by many Araneus species. Close to 50 species occur in North America, and several occur around gardens or outbuildings. Most are chunky-bodied, and some have humps on the abdomen. The best known of these is the barn orbweaver (A. cavaticus), a common spider east of the Great Plains that is the model of E. B. White’s children’s story Charlotte’s Web. (The featured spider in the book is named Charlotte A. Cavatica.) The large humps on the abdomen and some dark spotting of the plains orbweaver (A. gemmoides), a common species in the western states and provinces, often lead to it being referred to as the “catfaced spider.” A species of very similar appearance found along the West Coast is A. gemma.

640

A

B

A. Dysdera crocata, a predator of sowbugs and pillbugs. WHITNEY CRANSHAW

B. Typical orb web. WHITNEY CRANSHAW

C. Black-and-yellow

garden spider. DAVID CAPPAERT, BUGWOOD.ORG

D. Banded garden spider female and male (upper right). WHITNEY CRANSHAW

E. Golden silk

C

spider.

E

DAVID CAPPAERT, BUGWOOD.ORG

D F

F. Plains orbweaver, also known as the “cat-face spider.” WHITNEY CRANSHAW

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES Many also have distinctive patterning on the abdomen, such as marbled orbweaver (A. marmoreus), shamrock orbweaver (A. trifolium), and lattice orbweaver (A. thaddeus). The cross orbweaver (A. diadematus) is a European species introduced into both the northeastern and northwestern U.S. and is steadily extending its range. The eight Neoscona species also produce concentrically patterned webs. These somewhat resemble Araneus spiders, but they all have a smoothly oval abdomen and tend a bit smaller. Common species include the arabesque orbweaver (N. arabesca), western spotted orbweaver (N. oaxacensis), and arboreal orbweaver (N. crucifera). The sharply angular projections present on the body of Micrathena species often attract attention when they are observed. The most common species occur east of the High Plains, including the spined micrathena (M.  gracilus), white micrathena (M. mitrata), and arrowhead micrathena (M. sagittata). Micrathena funebris is present in southern Arizona and southern California. Another orbweaver marked with very prominent projections extending from a broad abdomen is Gasteracantha cranciformis (spinybacked orbweaver), found in the southeastern states. 1

Araneae: Araneaidae

Longjawed and Orchard Orbweavers1 These orbweaving spiders usually orient the orb horizontally or at a slight angle to the ground. Many longjawed spiders seem to prefer aquatic habitats, so their webs will be found near lakes, ponds, streams, and garden water features. They have very slender bodies with longs legs, but their enlarged jaws (fangs) are what catch most attention. The orchard spider, Leucauge venusta, is a very common species that makes its orb web below a mass of tangled webbing. Where prey is abundant, large numbers of longjawed spiders may build masses of intertwining webs among landscape and garden plants. 1

Araneae: Tetragnathidae

below left: Spinyback orbweaver. DAVID CAPPAERT, BUGWOOD.ORG

below: Orchard spider. DAVID SHETLAR

A

B

C D E

A. Marbled orbweaver. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Shamrock spider. DAVID CAPPAERT, BUGWOOD.ORG

C. Arabesque orbweaver. DAVID CAPPAERT, BUGWOOD.ORG

D. Spined micracantha. DAVID CAPPAERT, BUGWOOD.ORG

E. Longjawed spider. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Cobweb Weaver Spiders1 The webs produced by cobweb weaver spiders appear as disorganized tangles of webs, typically located in a sheltered areas such as under a roof, along a fence, in a corner of a greenhouse, or within a plant. The American house spider, Parasteatodea tepidariorum, is the most common species found in and around buildings in much of North America. Other common cobweb weavers are in the genus Steatoda, including the triangulate cobweb spider (S. triangulosa), S. borealis, and S. grossa. The latter two are sometimes referred to as “false black widows” because of similar body form and dark coloration of widow spiders. While the venom of most cobweb weavers is harmless to humans, this family also contains the “widow spiders” in the genus Latrodectus, which do possess a neurotoxic venom that can produce illness in humans. Five species can be found within the U.S. with the most common including the northern black widow (L. variolus), black widow (also called southern black widow) (L. mactans), and the western black widow (L. hesperus). The adult females of these species are generally black in color, but immature stages may have white or yellow markings on the upper surface. The males are often brightly colored with mottled white and yellow markings. In the Gulf States, there is an introduced species, often called the brown widow (L. geometricus). This species can range from dark to light brown and often has light markings on the abdomen, and the hourglass is a light orange color. All widow spiders can be recognized by having some red to redorange marking, often in a vaguely hourglass pattern, on the underside of the abdomen. Widow spiders do not usually like disturbance or brightly lit areas American house spider. and are infrequent in gardens, preferring more protected sites DAVID SHETLAR such as wood piles, dark corners of outbuildings, and basement window wells. In some situations they construct webs under or near landscape lights from which they emerge at night to capture insects attracted to the lights, a habit shared by many other spiders. Widow spiders can be abundant at times, but because of their secretive habits they are rarely contacted by humans and bites are very infrequent. 1

Araneae: Theridiidae

Lynx Spiders1 Lynx spiders hide among vegetation and ambush passing insects. They have very spiny legs and the tip of the abdomen comes to a point. A common species that attracts attention in the southeast is green lynx spider (Peucetia viridans), which is fairly large and has bright green coloration. Oxypodes scalaris (western lynx) and Oxypodes salticus (striped lynx) are two lynx spiders that occur most broadly across North America. 1

Araneae: Oxyopidae

644

A

B

C D

A. A “false black widow,” Steatoda species. WHITNEY CRANSHAW

B. Black widow female

tending egg sac.

JIM KALISCH, UNIVERSITY OF NEBRASKA

C. Male western widow. WHITNEY CRANSHAW

D. Green lynx spider

tending eggs. DAVID SHETLAR

E. Green lynx spider. DAVID SHETLAR

F. An Oxypodes species

of lynx spider. DAVID SHETLAR

E

F

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Funnel Weavers1 The funnel weaver spiders make distinct webs that include a horizontal flat sheet of web with a funnel-shaped tube at one end. Their webs are commonly found in lawns, among tall grass, in dense shrubbery, and in corners of buildings, wood piles, and other debris. Small threads extend above the sheet of webbing that can trip passing insects and cause them to fall onto the main web, where they are rapidly subdued by the spider waiting nearby in the funnel retreat. Funnel weaver spiders are most commonly observed in late summer and early fall, as they mature, and the webs are particularly conspicuous when covered with dew. These usually involve various “grass spider” species in the genera Hololena and Agelenopsis, which are also common nuisance invaders of homes in late season. Most often found indoors are males, many of which possess grossly enlarged pedipalps used for sperm transfer. Funnel weaver spiders in the genera Tegenaria and Eratigena may also be found both outdoors and indoors, and the barn funnel weaver (T. domestica) is among the most common spiders found within buildings in North America. Often attracting more attention because of their large size are Eratigena atrica and E. agrestis (“hobo spider”). The funnel weaver spiders are very commonly mistaken for wolf spiders or brown/recluse spiders. Funnel weaver spiders are harmless to humans. 1

Araneae: Agelenidae

Prowling Spiders1 Five species of prowling spiders can be found across North America, but those most commonly encountered are in the genus Cheiracanthium. The agrarian sac spider (C. inclusum) is a native species that usually has a brown body and a yellow to light green abdomen; the A funnel weaver, Hololena holo. yellow-legged sac spider (C. mildei) is a WHITNEY CRANSHAW foreign introduction that has spread across most of North America and is usually lighter in color. Prowling spiders are active hunters that feed at night. For a daytime retreat they usually construct a two-sided sac of silk between two leaves, under stones or loose bark, or where two walls meet. The yellow sac spider is a common home invader, where it can remain active year-round. Adult spiders can bite humans if handled or accidentally confined against the skin; bites that do occur should be promptly treated to prevent bacterial infection. 1

Araneae: Eutichuridae

646

B C

A D

E

F

A. Agelenopsis species funnel weaver, female. WHITNEY CRANSHAW

B. Funnel weaver web in juniper shrub. WHITNEY CRANSHAW

C. Funnel weaver in funnel retreat of web. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Agelenopsis species funnel weaver, male. WHITNEY CRANSHAW

E. Sac spider female. WHITNEY CRANSHAW

F. Sac spider male. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Cellar Spiders1 As their name implies, these spiders often reside in dark, undisturbed locations like cellars, unused basements, and storage sheds. They have very long legs and small bodies, are often confused with daddy longlegs, but these true spiders hang out in tangled webs of silk. An unusual habit of the females is to carry their egg sac in their jaws until the eggs hatch. Cellar spiders feed primarily on other spiders. Despite the common rumors in some regions (especially the Pacific Northwest), cellar spiders are harmless with fangs too small to pierce skin and an absence of venom with hazards to humans. 1

Araneae: Pholcidae

Brown or Recluse Spiders1 These are generally small to medium spiders that are light brown in color, have long legs, and appear to be hairless though their bodies are covered with dense, short hairs. The brown recluse (Loxosceles reclusa) has a native range of Kansas and Missouri down to Mexico, but it has been spread through movement of infested furniture and household goods to many other locations. This species is not well adapted to extremely cold or wet habitats. An imported species, the Mediterranean recluse (L. rufescens) has been introduced into the U.S. and is now quite broadly distributed, although it is almost always found in dark areas of large buildings and occurs only rarely outdoors. An adult brown spider usually has a leg-span the size of a quarter. Outdoors, brown recluse spiders make thin, sticky, sheetlike tangle webs, usually under the bark of dead trees, spaces under stones, or between pieces of firewood. Inside buildings, they prefer to make webs along the floor of an undisturbed area. The uniformly colored brown abdomen and absence of any banding on the legs is one way to distinguish these spiders from some for which they are commonly mistaken, such as funnel weavers (Agelenidae family). Adult spiders are capable of piercing human skin, and their venom may cause a local lesion. More extensive tissue damage develops from the effects of the venom in a very small percentage of cases. When this occurs, damage can be extensive because of slow-healing ulcerations that may result in serious scarring and, in very rare instance, have more systemic effects that can be life threatening. As with wounds by other insects and spiders that break the skin, these areas are also susceptible to secondary bacterial infections, so brown recluse bites (and bites of any spider or insect that breaks the skin) should be immediately cleaned and disinfected. 1

Araneae: Sicariidae

Daddy Longlegs/Harvestmen1 Daddy longlegs are distant relatives of spiders and are classed in their own order, Opiliones. More than 200 species occur in North America, including several common species of European origin. Leiobunum species and Phalangium opilio are usually the daddy longlegs most commonly encountered in gardens. Like other arachnids, the daddy longlegs have 4 pairs of legs, but the cephalothorax and abdomen are broadly joined (spiders have a “waist” between the cephalothorax and abdomen). However, the legs are usually extremely long, proportionately longer and more conspicuous than with any other animal. Males, although somewhat smaller-bodied 648

A C

B D

E A. Longbodied cellar spider Pholcus phalangoides carrying eggs. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Brown recluse spider female. DAVID SHETLAR

C. Brown recluse spiders caught on sticky trap. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Phalangium opilio feeding on ant. DAVID SHETLAR

E. Leiobunum species of daddy long legs. WHITNEY CRANSHAW

than females, have particularly long legs. The body is generally globular and lacks distinct body regions, although the abdomen is clearly segmented. Daddy longlegs have two small eyes mounted on tubercules of the head. Their jaws (chelicerae) are designed to tear food apart so it can be mixed with digestive fluids. Unlike spiders they do not possess poison glands, although their purported toxicity is a very widespread (worldwide)—and baseless— urban legend. Daddy longlegs also have no glands to produce silk. Daddy longlegs are generalists in their feeding habits. They may consume small, soft-bodied insects, slugs, and mites and are generally considered beneficial in their effects within a garden. They also scavenge dead insects, spiders, and earthworms. Some may also feed on plant juices, but do not produce significant plant injuries. Most have a 1-year life cycle, with adults maturing late in the season, a habit leading to the other common name “harvestmen.” However, the life cycle of others, including the ubiquitous Phalanigum opilio, may not be as synchronized, so both reproductinve adults and immature stages may be present through much of the growing season. Occasionally large groups of daddy longlegs will mass together in protected areas (on tree trunks, sides of buildings, etc.), a behavior that seems to help provide collective protection from predators. 1

Opiliones: Phalangiidae, Sclorsomatidae, Laniatores, and others

649

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PREDATORS OF INSECTS AND MITES

Predatory Mites1 Many types of mites are predators of plant-feeding spider mites. Typically, predatory mites are pear-shaped and have shinier bodies than spider mites. They are also considerably more active and can usually be detected by being considerably faster-moving than their prey. Most predatory mites are generalist predators and may feed on eriophyid mites, thrips, and eggs of insects. Pollen is also important in the diet of some predatory mites. Predatory mites can often provide good control of spider mites but tend to require higher humidity than spider mites. They are often very susceptible to insecticides, which they can pick up by contacting residues on plant surfaces, taking water from plants, or eating contaminated pollen. In most landscapes and gardens, predatory mites can be conserved by treating only plants with pest populations that need quick knockdown (no general cover sprays) or using insecticides that have minimal impact on predatory mites. Phytoseiidae is the largest family of predatory mites with representatives worldwide. The family includes several species reared and sold for biological control of mites and thrips. Typhlodromus pyri is often found on fruit and ornamental trees and survives well in northern climates. Females overwinter in crevices on trunks and branches. On warm spring days, these adults emerge to begin their search for eggs and spider mites, but they can survive by feeding on pollen, fungi, and plant fluids. Normally, there are three to four generations each summer. Amblyseius fallacius is another common species that survives better in more moderate zones. This species as well as other Amblyseius are commonly sold for spider mite and thrips control in greenhouses, small fruit crops, vegetables, and ornamental plants. (Each species of Amblyseius may have different temperature and humidity tolerances, so check with commercial suppliers to determine the species best suited for your needs.) Phytoselius persimilis is one of the most commonly sold species, but it is a tropical species best suited for high humidity and moderate temperature locations such as greenhouses. The western predatory mite, Galendromus (=Typhlodromus) occidentalis, is a native of the western U.S. but it has been spread widely through commerce. It is capable of surviving a wide range of temperatures, can survive most winters, and often will have 8–10 generations in a season. Perhaps the most active mites one might observe on a plant are whirligig mites (Anystidae family). Compared to the phytoseiid mites and spider mites, these are fairly large and often reddish or orange. They can run extremely rapidly in erratic, spiraling patterns. The whirligig mites are generalist predators that usually feed on spider mites or thrips. Bdellid mites (Bdellidae family) are often called snout mites because they have elongated mouthparts that project forward. They are relatively common in soils, in leaf litter, and on plants, where they prey on a variety of other mites and small insects. Camerobiid mites (Camerobiidae family) are usually round in body shape with long legs often held straight out from the body. These are swift-moving mites that are often red or orange in color. Both mites are relatively common in landscapes but not usually reared for sale. A rather unusual group of mites are the velvet mites. These live in or on the soil, and young stages of many are parasites of insects. Young stages of some in this family (Trombiculidae) are parasites of other animals and known as chiggers. Adults are general predators that feed primarily on insect eggs. Their reddish color, often bright red, attracts attention, although velvet mites are never very abundant around a garden. A closely related family of mites, Erythraeidae, contains a subfamily Balaustiinae of large red mites commonly known as “concrete mites.” Balaustium mites have lost their parasitic habits and feed primarily on pollen. They can cover sidewalks, fence posts, and sides of buildings in late spring. They will stain light-colored clothing if crushed, so they can become a nuisance issue. Sometimes they are mistaken for a type of chigger, but balaustium mites are not known to bite humans. 1

Acari: Phytoseiidae, Anystidae, Bdellidae, Camerobiidae and others

650

A B

C D E

F

A. Predatory mite Amblyseius fallacius feeding on spider mite. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

B. Western predatory mite Galendromus occidentalis

feeding on spider mite.

JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

G

C. Whirligig mite, Anystis agilis. HAROLD J. LARSEN, COLORADO STATE UNIVERSITY

D. Whirligig mite. DAVID SHETLAR

E. Bdellid mite. TOM MURRAY

F. Velvet mite. DAVID SHETLAR

G. Balaustium mite. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

PREDATORS OF INSECTS AND MITES

Centipedes All centipedes develop as predators of other arthropods. They are rarely abundant enough to have much effect on insect populations but feed on a wide variety of potential pests that spend part of their lives in or on the soil surface. The most common centipedes found in yards and gardens are the stone centipedes,1 usually about 1 inch long, red-brown in color, and possessing 15 pairs of legs. The largest centipedes are “bark centipedes” of the genus Scolopendra2 which possess 21–23 pairs of legs. Some Scolopendra species that occur in the southern U.S. can be 6 inches in length, and almost all are large enough to produce a very painful bite if handled carelessly. When digging or moving stones and landscape timbers, one often finds soil centipedes.3 These centipedes are very slim, generally yellowish in color and have more than 29 pairs of legs. These are blind and their fangs are too small to pierce human skin. The house centipede (Scutigera coleoptrata)4 is a centipede of rather bizarre appearance with extremely long legs, 15 pair on the adults. It is one of the few centipedes adapted to living and reproducing within buildings, where it feeds on spiders, cockroaches, and other indoor insects. However, it is more common (although less commonly seen) outdoors. Outside, these centipedes forage at night and may be noticed around lights that attract other insects. This species will readily self-amputate legs that are grabbed or stuck, but it can immediately alter its walk to compensate for the loss of an appendage and still be capable of rapid escape. 1

Chilopoda: Lithobiomorpha; 2 Chilopoda: Scolopendromorpha; 3 Chilopoda: Geophilomorpha; 4 Chilopoda: Scutigeromorpha

Predatory Snails A few snails are primarily predatory, feeding on soft-bodied invertebrates (slugs, snails, earthworms). The best known is decollate snail (Rumina decollata)1, a Mediterranean species that has been introduced into North America and feeds on the brown garden snail. Euglandina rosae2, known as rosy wolfsnail or rosy predator snail, has been introduced into some areas to control the giant African snail; in Hawaii it is considered to be an invasive species as it has led to the extermination of many native tree snails. 1

Gastropoda: Subulinidae; 2 Gastropoda: Spiraxidae

652

A B

C D

E

F

A. Stone centipede. DAVID SHETLAR

B. Ground centipede. DAVID SHETLAR

C. Centipede tending eggs. DAVID SHETLAR

D. House centipede. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. A large scolopendrid centipede,

Scolopendra polymorpha. WHITNEY CRANSHAW

F. Decollate snail. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA IPM PROGRAM

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

HUNTING WASPS AND ANTS Many wasps and ants are predators of other arthropods. In these insects the adult is the predatory stage, often collecting insect prey to feed their developing young. Ants and the various paper-nesting wasps are social insects. These produce a colony and different individuals may have specialized tasks, with usually a single queen the sole reproducing form. Other wasps are solitary and the female does all tasks involved in prey capture, nest construction and rearing of young.

Predatory Ants1 A wide variety of habits exist among the hundreds of species of ants found in North America. Some are considered pests because they occur in nuisance numbers in homes, nest in wood, or damage plants. Many are important predators of insect pests, particularly in sites such as turfgrass; several are largely predaceous, or eat insects as part of their diet. fire ants (Solenopsis species) (page 518), found in the southern U.S., are largely predatory and may devastate insect populations that occur in the vicinity of nests. Ghost ant (Tapinoma melanocephalum) has been found to feed on spider mites and many types of insects and has been considered as a useful biological control species in greenhouses. Many of the other common ants found in and around yards and gardens, such as field ants (Formica species), carpenter ants (Camponotus species), and pavement ants (Tetramorium caespitum), feed on both living and dead insects as well as on sweet materials such as honeydew. 1

Hymenoptera: Formicidae

Paper Wasps1 Paper wasps annually make open-celled paper nests that are not covered with a papery envelope. They are usually observed hanging from eaves and the ceilings of outbuildings, but they may also nest in aboveground hollows and along the branches of trees and shrubs. The great majority of those found in North America are in the genus Polistes. In addition to native species, a recently introduced species, now widely established in North America, is the European paper wasp, Polistes dominula. East of the Rocky Mountains, P. annularis is a common redbrown species with a black abdomen that has a single yellow band. This species can make nests that contain 1,000 or more individuals by the end of the summer. P. exclamans, P. fuscatus (northern paper wasp), and P. dorsalis are common species that are usually more brightly colored with red, brown, and yellow markings. In areas of western North America, the yellowlegged paper wasp (Mischocyttarus flavitarsis) may be common. In the southern states, Mischocyttarus mexicanus commonly makes small nests in rolled plant leaves or under the protection of palm leaves. Both these species are somewhat smaller than Polistes wasps and have a distinctively narrow first segment of the abdomen. All the paper wasps rear their young on chewed-up insects. They are commonly seen searching plants for caterpillars, beetle larvae, and other suitable prey, which are then chewed and fed to the grublike larvae within the nest. Paper wasps are very valuable in the biological control of many pest insects in yards and gardens. Paper wasps can sting, and some species will aggressively defend the nest; however, unlike yellowjackets, they do not scavenge at foods. 1

Hymenoptera: Vespidae

654

A

C D F

G

B

E A. Field ants preying on caterpillar. DAVID SHETLAR

B. Red imported

fire ants preying on mole cricket. DAVID SHETLAR

C. Ghost ants. DAVID SHETLAR

D. Carpenter ant feeding on small fly. WHITNEY CRANSHAW

E. Polistes paper wasp

feeding on cutworm.

H

I

DAVID SHETLAR

F. Nest of Polistes

dorsalis.

DAVID SHETLAR

G. Northern paper wasp

chewing on fence to collect wood fibers. DAVID SHETLAR

H. European paper

wasp feeding on cabbagworm. WHITNEY CRANSHAW

I. Nest of the European

J

paper wasp.

JIM KALISCH, UNIVERSITY OF NEBRASKA

J. Yellowlegged paper

wasp at nest.

WHITNEY CRANSHAW

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

huNtiNg WasPs aNd aNts

Hornets and Yellowjackets1 The baldfaced hornet (Dolichovespula maculata) and aerial yellowjacket (D. maculata) create large aerial nests covered with a papery shell, produced from chewing on weathered wood or cardboard. These nests are produced annually, started by a single fertilized female (queen) in late spring and then abandoned at the end of the season. Both these insects rear their young strictly on a diet of living insects, particularly caterpillars. Although they sting if the nest is disturbed, the activities of these insects are largely beneficial to gardeners because of their importance as biological control agents. Of far more mixed effects are the activities of yellowjackets (Vespula species) (page 586). Some species are primarily predators, such as the prairie yellowjacket (V. atripilosa), which feeds largely on flies, but the majority of North American yellowjackets have much broader food choices, and most are scavengers that frequently visit outdoor dining areas and trash cans. These types of yellowjackets, which include the German yellowjacket (V. germanica), western yellowjacket (V. pensylvanica), and eastern yellowjacket (V. maculifrons), may feed on some live insects, but more often will consume dead insects and earthworms and scavenge carrion—and feed on meaty foods laid out by humans. They also forage on sweet materials, particularly late in the season, and can be serious nuisance pests during outdoor dining. As yellowjackets are the predominant stinging insect in much of North America, often forage as scavengers rather than as predators, and are not significant pollinators, yellowjackets are usually considered undesirable around the garden. Yellowjackets make paper nests that include multiple layers of cells and are covered with a paper envelope, in the manner of the Dolichovespula species; however, the nests are always hidden, often belowground. Normally all the hornets and yellowjackets abandon their nests upon the arrival of cold winter temperatures; on rare occasions, nests of the southern yellowjacket, V. squamosa, can persist more than one season in warmer areas of the southern U.S. Only newly emerged, mated females can survive freezing temperatures, and these build new nests the following spring. These wasps do not reoccupy old nests, a habit that allows them to avoid persistent pathogens and parasites. Once a hard freeze has occurred, old nests can be removed and potential nesting cavities sealed to prevent future colonization of these areas. The European hornet (Vespa crabro germana) (page 588) is an introduced species often twice the size of the baldfaced hornets and three times the size of yellowjackets. This is a relatively nonaggressive species that feeds primarily on captured insects, but the workers are known to chew the bark off tree and shrub branches. They will often return to these plant wounds to lick up exuding sap. It prefers to nest in hollow logs but will build nests in building attics and other voids. 1

Hymenoptera: Vespidae

Potter Wasps1 The potter wasps are related to the yellowjackets and paper wasps but do not produce colonies but instead construct mud nests for rearing young. Those in the genus Eumenes produce nest cells in the form of clay pots they provision with paralyzed caterpillars and beetle larvae. A single wasp larva develops within each of the nest cells. The potter wasps are nonaggressive and rarely sting. 1

Hymenoptera: Vespidae (Eumeninae)

656

C

A

B

E

F

D A. Nest of a baldfaced hornet. DAVID SHETLAR

B. Baldfaced

hornet.

DAVID SHETLAR

C. Prairie

yellowjacket, a predatory species that often feeds on flies. WHITNEY CRANSHAW

D. Yellowjacket nest

entrance on ground. DAVID SHETLAR

E. Western

yellowjacket feeding on cabbageworm. WHITNEY CRANSHAW

F. Western

yellowjacket scavenging on meat. WHITNEY CRANSHAW

G. Large nest of

eastern yellowjacket established among hay bales. TERRY S. PRICE, GEORGIA FORESTRY COMMISSION, BUGWOOD.ORG

H. European hornets. JIM BAKER, NORTH CAROLINA STATE UNIVERSITY, BUGWOOD.ORG

G H I

J

I. Potter wasp larva extracted from nest cell. WHITNEY CRANSHAW

J. Potter wasp

bringing caterpillar prey to nest. JON YUSCHOCK, BUGWOOD.ORG

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

huNtiNg WasPs aNd aNts

Hunting Wasps The hunting wasps are solitary wasps and do not produce a colony like those of the social wasps (paper wasps, yellowjackets, hornets). Instead the females construct an entire nest and do all the foraging needed to feed their young, working alone. Nearly a thousand species of these wasps occur in North America, but only a few are commonly noticed. Depending on species, some hunting wasps make nests in soil in the form of a burrow connected to underground chambers. Others excavate tunnels in the pith of plants or utilize holes made by wood-boring insects that have emerged from tree trunks or logs. A few create nest cells out of mud. Each type of hunting wasp specializes in a different kind of host insect. The largest of the hunting wasps are the cicada killers (Sphecius spp.)2 that specialize in the large dog-day cicadas (page 408). Cicada killers dig large underground nests that may penetrate well below a foot and result in conspicuous mounds. Many other hunting wasps nest in the soil, such as Ammophila spp.,1 which specialize in hairless caterpillars such as hornworms and cutworms, Podalonia spp.,1 which target cutworms and other caterpillars in the family Noctuidae, Bembix spp., which specialize in flies, and Cerceris spp.,2 Bembix pruinosa returning to ground nest with horse fly prey. which collect weevils and wood-boring beetles. HOWARD ENSIGN EVANS Various orthopterans are the prey of some of the common hunting wasps. Katydids and crickets are prey used by the Sphex species,1 which are large wasps that include the great golden digger wasp (S. ichneumoneus) and S. pensylvanicus. Grasshoppers are the prey of most Prionyx spp.,1 field crickets (Gryllus spp.) of the steel-blue cricket hunter (Chlorion aerarium),1 and tree crickets (Oecanthus spp.) of the grass-carrying wasps of the genus Isodontia.1 Most of these make nests in the soil, but the last use existing cavities aboveground such as those left by wood borers. The grass-carrying wasps use grass to separate the rearing chambers, and it is not uncommon for them to use the crevices present in the sash tracks of windows, lending them the name “window wasps.” Several small hunting wasps that prey on insects such as aphids, psyllids, and leafhoppers use small cavities in plants for nest sites. Pemphredon spp.2 that hunt aphids excavate cavities from the pith of plants such as rose and caneberries. Passaloecus spp.2 often use preexisting cavities, including predrilled blocks used to attract cavity-nesting bees. Two kinds of hunting wasps, known as “mud daubers” fully form nest cells using mud. The black-andyellow mud dauber (Sceliphron caementarium)1 is found throughout North America and makes a series of cylindrical cells under eaves and in other sites protected from rainfall. Considerably longer mud nest cells are produced by the organpipe mud dauber (Trypoxylon politum),2 which occurs in eastern North America, extending to Texas. Both these wasps use spiders as prey, often packing each cell with a dozen or more paralyzed spiders that are quickly consumed by their larvae. Despite their often fearsome appearance, the hunting wasps rarely sting and do not possess venom that causes pain on par with the social wasps (e.g., paper wasps, yellowjackets). 1

Hymenoptera: Sphecidae; 2 Hymenoptera: Crabronidae

658

A

B

C D

E

F

G

A. Cicada killer. DAVID SHETLAR

B. Cicada killer returning to nest with prey.

H

I

DAVID SHETLAR

C. Great golden digger wasp. DAVID SHETLAR

D. An Ammophila species hunting wasp with

caterpillar prey.

DAVID CUPPAERT, BUGWOOD.ORG

E. Grass carrier wasp with tree cricket prey. JOHNNY N. DELL, BUGWOOD.ORG

F. Debris excavated from nests of grass carrying wasps. JIM KALISCH, UNIVERSITY OF NEBRASKA

J

G. Pemphredon wasp resting on leaf. WHITNEY CRANSHAW

H. Black-and-yellow mud dauber constructing nest. HOWARD ENSIGN EVANS.

I. Organpipe mud dauber returning to nest. DAVID SHETLAR

J. Nest cell of black-and-yellow mud dauber opened

to expose spider prey.

KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

huNtiNg WasPs aNd aNts, aNd iNsEct Parasitoids

Spider Wasps1 The spider wasps are also hunting wasps of solitary habit. All specialize in spiders, choosing hosts that are larger than the wasp. The spiders are incapacitated by a sting, then dragged to a tunnel in the soil, which the wasp either finds (i.e., the burrow of the spider) or constructs. The host spider is then cached in the nest and an egg laid on it. Upon egg hatch, the spider wasp larva rapidly consumes the immobilized spider. Adult spider wasps are fairly common at flowers feeding on nectar and pollen. Spider wasps are capable of producing a painful sting, but they are not aggressive species and sting only if handled. 1

Hymenoptera: Pompilidae

INSECT PARASITOIDS Many wasps and some flies develop as parasitoids. With these insects the adult female seeks insects that are appropriate hosts to support her young then lays an egg in or on the insect. As the parasitoid larva develops, it feeds initially on nonvital tissue, and the insect host may show no external evidence of the parasite; however, as the parasitoid larva matures it ultimately does kill the insect on which it develops. Most parasitoid larvae develop inside their host (endoparasitoids). A few, notably in the wasp family Eulophidae, may pass through stages that feed from the outside of the host (ectoparasitoids). However, larvae of many parasitoids emerge from the host when feeding is completed and pupate on the outside. Adult stages of insect parasitoids usually feed on nectar, pollen, and honeydew; a few feed on blood of host insects which they acquire by puncturing with their ovipositor.

Tiphiid and Scoliid Wasps These wasps are mostly parasites of white grub larvae. Adult wasps can be fairly large and may superficially resemble yellowjackets or other hunting wasps. Myzinum1 and Tiphia1 are the two most common genera in North America. Scolia dubia2 is more than an inch long and generally black with orange-and--yellow markings on the abdomen. This hairy wasp will persistently hover over turf or garden soil infested with green June beetle (page 468) larvae. Both tiphiid and scoliid wasps dig into the soil, paralyze their prey in the soil, and attach an egg. The wasp larvae remain on the outside of the grub body while the head is buried inside the body. 1

Hymenoptera: Tiphiidae; 2 Hymenoptera: Scoliidae

Pelecinid Wasps The pelecinid wasps have only one North American species, Pelecinus polyturator,1 but it is a large black wasp of unusual appearance. The abdomen of the female is extremely elongated, extending an inch and a half, which allows laying eggs in soil. Larvae are parasites of white grubs (scarabs) in soil. 1

Hymenoptera: Pelecinidae

660

A. Spider wasp with spider prey. DAVID CAPPAERT, BUGWOOD.ORG

A

B. Spider wasp dragging spider prey.

B

WHITNEY CRANSHAW

C D

C. A Myzinum

species of tiphiid wasp. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. A Tiphia species of tiphiid wasp. DAVID SHETLAR

E. Larva of a Tiphia

wasp developing on white grub host. DAVID SHETLAR

F. Scoliid wasp

Campsomeris pilipes digging in soil in search of host. WHITNEY CRANSHAW

E

G. A scoliid wasp. DAVID SHETLAR

H. Pelecinid wasp. DAVID SHETLAR

F

G

H

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

iNsEct Parasitoids

Ichneumonid Wasps1 These wasps are medium to fairly large, slender wasps. Antennae are quite long, and the females usually possess a long and conspicuous ovipositor. Ichneumonid wasps are most commonly encountered as parasites of caterpillars. Beetles, sawflies, and other wasps are other hosts. Common genera include Hyposoter, Diadegma, Ophion, and Exochus. The family Ichneumonidae is one of the largest of any insect group, with 3,300 described species in North America. The largest ichneumon wasps are those in the genus Megarhyssa, which are parasites of horntail larvae, a type of wood-boring sawfly. These giant ichneumon wasps may be 3 inches long, including the very long tail-like ovipositor used to penetrate wood. 1

Hymenoptera: Ichneumonidae

Braconid Wasps1 Braconids are very similar to ichneumonids but usually much smaller. This large and important family of wasps has more than 1,900 North American species. Bracon, Chelonus, Leiophron, Macrocentrus and Opius are common genera that generally attack caterpillars. The white or yellowish pupae of Cotesia species, spun on or adjacent to their caterpillar host, are among the most commonly observed stages of any parasitic wasp. Braconids are a very diverse group, with some taxonomists elevating the 29 or more subfamilies to family level. There are subfamilies that specialize in parasitizing almost all the other orders of insects. The aphid parasitoids subfamily (Aphidiinae) are among the most ubiquitous of the smaller braconid wasps, found almost invariably among aphid colonies. As the wasp larva develops within an aphid, the host typically swells, grows lighter in color, and becomes affixed to the leaf. Aphids killed in this manner are often referred to as “aphid mummies.” A circular hole cut in the aphid by the emerging wasp is also characteristic. Among the common genera of aphid wasps are Trioxys, Diaeretiella, Lysiphlebus, and Aphidius. 1

Hymenoptera: Braconidae

right: The giant ichneumon wasp Megarhyssa macrurus, a parasitoid of pigeon tremex larvae. DAVID SHETLAR

below: Adult braconid wasps emerged from woollybear host. JIM KALISCH, UNIVERSITY OF NEBRASKA

B D A E

C A. Ichneumonid wasp, Itoplectis

conquisitor, ovipositing into caterpillar hosts. GERALD J. LENHARD, LOUISIANA STATE UNIVERSITY, BUGWOOD.ORG

B. Ichneumonid wasp ovipositing into fall webworm caterpillars. DAVID SHETLAR

C. Megarhyssa atrata ovipositing

into trunk for horntail host. DAVID SHETLAR

F

G

D. A braconid wasp, Aleiodes

indiscretus, oviposiiting into gypsy moth larva. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE

E. Cocoons of Cotesia glomeratus,

a braconid wasp parasitoid of imported cabbageworm. WHITNEY CRANSHAW

F. Braconid wasp larvae exiting host caterpillar.

H

I

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Cocoons of Cotesia

congregata on back of tobacco hornworm host. DAVID SHETLAR

H. Cotesia congregata adult, with

cocoons of pupae on caterpillar host. DAVID SHETLAR

I. Pupal cocoon of Dinocampus

coccinellae, a parasitoid of lady beetles. DAVID SHETLAR

J. Aphid parasitoid ovipositing. DAVID SHETLAR

J

K

K. Potato aphid “mummies”

showing evidence of parasitism by a braconid wasp. JIM KALISCH, UNIVERSITY OF NEBRASKA

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

iNsEct Parasitoids

Chalcid Wasps1 Known as chalcid wasps, this superfamily (Chalcidoidea) contains more than a dozen families that are generally tiny parasitic wasps. Many are small enough to parasitize insect eggs, but insect nymphs, larvae, or pupae can also be attacked. Many species of chalcids have been introduced as biological control agents of introduced scale, caterpillar, beetle, and fly pests. The pteromalid wasps (Pteromalidae family) include species that are very important parasites of sawflies. Another group are those that develop on larvae and pupae of various filth-breeding flies, some of which are sold commercially as “fly predators” or “fly parasites” to control nuisance flies around livestock operations. Pteromalus, Perilampus, Spalangia, and Nasonia are among the genera of pteromalid wasps most important for biological control of pest species. Encyrtid wasps (Encyrtidae family) are very small wasps that develop internally in eggs, larvae, or pupae of certain insects. The genera Anagyrus, Leptomastix, and Metaphycus include species that serve as important natural enemies of some of the most common mealybugs and soft scales. An unusual species is Copidosoma truncatellum, which A pteromalid wasp lays its eggs in the eggs of cutworms, loopers, and other caterpillars. The ovipositing into a fly pupa. USDA ARS PHOTO UNIT, USDA AGRICULTURAL species is polyembryonic, and numerous larvae—sometimes more than RESEARCH SERVICE, BUGWOOD.ORG 1,000—develop from the few eggs originally laid. The larvae of this wasp develop throughout the larval life of the caterpillar host, killing it as it prepares to pupate. Aphelinid wasps (Aphelinindae family) include many important species that attack insects in the order Hemiptera. Several Encarsia species are very important as parasites of whiteflies and cause the host nymph to turn black when parasitized. Aphelinus is a genus that includes important parasites of aphids, which also characteristically turn dark black when parasitized. Coccophagus and Aphytis include many of the parasites most important in control of scale insects. Most true chalcid wasps (Chalcididae family) are internal parasites of caterpillars, although some develop in fly larvae. They are distinguished by having very enlarged femurs on the hind legs, and are some of the larger wasps in the subfamily, occasionally reaching ⅜ inch in length. Brachymeria is the most common and widespread genus among the chalcid wasps in North America. The eulophid wasps (Eulophidae family) are very small (typically ca. 1⁄25 inch) and many develop as external parasites of their hosts. Some of the most conspicuous are species of Euplectrus that develop on the body of several kinds of caterpillars. Others are parasites of scales, psyllids, and flies—including many of the leafmining flies. Some eulophids are egg parasites of beetles. The smallest parasitic wasps—and smallest insects known—are those that develop as internal parasites of insect eggs. The trichogramma wasps (Trichogrammatidae family) are well known as parasites of caterpillar eggs, and several species (T. pretiosum, T. platneri, T. brassicae, T. minutum) are widely available for sale as biological control agents. Even more minute are the fairyflies (Mymaridae family), which include the genus Anagrus, a group that develops in the eggs of leafhoppers and can be important biological controls. 1

Hymenoptera: superfamily Chalcidoidea

664

A

B

C D

E A. Cabbage looper larva packed with pupae of a Copidosoma floridanum, an encyrtid wasp. DAVID SHETLAR

B. Encarsia formosa, an aphelinid parasitoid

of greenhouse whitefly.

DAVID CAPPAERT, BUGWOOD.ORG

C. Greenhouse whiteflies parasitized by

F Encarsia formosa (dark insects are parasitized). DAVID CAPPAERT, BUGWOOD.ORG

D. A parasitoid of scale insects, Coccophagus species. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

E. Phasnogophora sulcata, a chalcid

parasitoid of flatheaded borers. DAVID CAPPAERT, BUGWOOD.ORG

F. Tetrastichus planipennisi, a eulophid wasp introduced to control emerald ash borer. DAVID CAPPAERT, BUGWOOD.ORG

G. Larvae of an ectoparasitic eulophid wasp,

Euplectrus species, on back of caterpillar host. DAVID SHETLAR

H. Trichogramma wasp ovipositing in egg of a corn earworm. JACK KELLY CLARK, COURTESY OF UNIVERSITY OF CALIFORNIA STATEWIDE IPM PROGRAM

G H

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

iNsEct Parasitoids

Sarcophagid Flies1 Most sarcophagid flies feed on fresh carrion and are known as “flesh flies.” Others develop as parasites of insects, including grasshoppers, caterpillars, and beetles, and are sometimes important natural enemies of certain pest insects. For example Sarcophaga aldrichi is one of the most common natural enemies of tent caterpillars. It is sometimes called the “friendly fly” as it will frequently land on people, but it does not bite and is harmless to humans. Grasshoppers are often heavily attacked by sarcophagid flies in the genus Blaesoxipha. Sarcophagid flies are generally a little larger than a house fly and often have black bodies with gray thoracic stripes. Many have prominent red-orange eyes, and the egg-laying structures on the tip of the abdomen may also be red-orange, hence other common names of these insects are “red-eyed” or “red-tailed flies.” 1

Diptera: Sarcophagidae

Tachinid Flies1 The tachinid flies are a large and very important family of parasitic flies with about 1,300 North American species. All develop as internal parasites of other insects, including many caterpillars, beetles, true bugs, earwigs, and grasshoppers that occur as garden pests. Typical species somewhat resemble house flies but tend to have more stout, bristly hairs on the abdomen. Females usually glue an egg to the body of a host, often near the head, and the maggot larva burrows into the host’s body cavity. However, some tachinid flies insert larvae directly into the host insect, whereas others lay tiny eggs on foliage that hatch when ingested. 1

Diptera: Tachinidae

Tachinid fly laying eggs on walnut caterpillar. JIM KALISCH, UNIVERSITY OF NEBRASKA

666

Tachinid fly larvae emerged from pupa of a cecropia moth. JIM KALISCH, UNIVERSITY OF NEBRASKA

A. Sarcophaga aldrichii, a parasitoid of tent caterpillars. DAVID SHETLAR

B. A Blaesoxipha

A

species of sarcophagid fly, parasitoid of grasshoppers.

B

WHITNEY CRANSHAW

C D

C. Tachinid fly

ovipositing on yellownecked caterpillar. DAVID SHETLAR

D. Squash bugs

with attached eggs of a Trichopoda species of tachinid fly. WHITNEY CRANSHAW

E. Adult of a

Trichopoda species of tachinid fly. JIM KALISCH, UNIVERSITY OF NEBRASKA

E

F. Eggs of the tachinid fly Istocheta aldrichi laid on Japanese beetle.

F

JIM KALISCH, UNIVERSITY OF NEBRASKA

G. Cabbage looper

showing evidence of parasitism by developing tachinid flies (dark spots are breathing tubes of parasitoid larvae). WHITNEY CRANSHAW

H. Pupa of a tachinid

fly parasitoid of European earwig. WHITNEY CRANSHAW

G H

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

INSECT PATHOGENS Although infrequently observed, insects and mites often suffer from infection by pathogens, many of which produce lethal diseases. Certain kinds of fungi, bacteria, protozoa, and viruses can all kill insects, and many are important in their management. Viruses that produce disease in insects are most evident among the caterpillars and sawflies. One particularly gruesome group of insect viruses (nuclear polyhedrosis viruses/NPV) cause wilt disease. Caterpillars and sawflies infected by these viruses are killed rapidly, their virus-filled bodies hanging limply by their prolegs. At the slightest touch, the insects rupture, spilling the virus particles onto leaves below them to infect other insects. Wilt diseases are important biological controls of several caterpillars, including Alfalfa webworms killed by Bacillus thuringiensis. cabbage looper, gypsy moth, and Douglas-fir tussock moth. JOHN CAPINERA, UNIVERSITY OF FLORIDA Other types of viruses, known as granulosis viruses, act considerably more slowly. These other viruses may produce only modest external symptoms such as a chalky color of the infected insect or a general listlessness. A few of these have been commercially developed, including viruses that affect codling moth (Cyd-X®, Madex®) and corn earworm (Gemstar®). Several types of bacteria may infect insects and typically enter through the digestive system. Larvae of Japanese beetle are susceptible to Paenibacillus popilliae, producing milky disease that causes infected grubs to turn creamy white, grow poorly and often die. Related species infect other species of white grubs. An extremely infectious and potentially devastating disease of larval honey bees is American foulbrood, produced by Paenibacillus larvae. Various Serratia species also cause infections in many insects. Bacteria may also produce various toxins that can be lethal to insects. Bacillus thuringiensis (Bt) is the best known of these, capable of producing protein crystals that can destroy cells of the digestive system of susceptible species. A great many strains of this bacterium have been discovered, each of which produces compounds that affect insects differently. Several strains have been commercialized and are variously used to control certain caterpillars (kurstaki, aizawi strains), leaf beetle larvae (tenebrionis strain), larvae of mosquitoes, fungus gnats, and related flies (israelensis strain), and white grubs (galleriae strain). Fungi produce some of the more spectacular diseases of insects. A wide variety of insects succumb to fungus disease around the yard and garden. Fungus-killed insects and mites become stiff and, when conditions are right, covered with a white, light green, or pink “fuzz”—the spores of the fungus. Perhaps the fungal disease of insects most commonly encountered in a garden is Entomophthora muscae that infects various root maggot flies. Infected flies die stuck to the tops of plants and at other high points around the garden. This fungus can also infect house and blow flies, which may be seen stuck onto windows surrounded by a halo of spores. Grasshoppers infected with strains of E. grylli may be seen attached to upper stems of plants, where they die, stiffly clinging to the plant. Entomophaga maimaiga is an introduced fungus that produces devastating outbreaks among gypsy moth when spring moisture conditions are optimal for its spread and infection. 668

A

B

C D E

F

A. Gypsy moth larva killed by a nuclear polyhedrosis virus wilt disease. JOHN GHENT, JOHN GHENT, BUGWOOD.ORG

B. Sawfly larvae killed by a

nuclear polyhedrosis virus. STEVEN KATOVICH, BUGWOOD.ORG

C. Masked chafer grub showing

evidence of infection with a milky disease bacterium (on right). DAVID SHETLAR

D. Japanese beetle grub (on left)

showing evidence of infection with a Serratia species of bacterium producing amber disease. DAVID SHETLAR

E. Seedcorn maggot flies killed

by the fungus Entomophthora muscae. WHITNEY CRANSHAW

F. Gypsy moth larva killed by the

fungus Entomophaga maimaiga. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

iNsEct PathogENs Beauveria bassiana is a very common fungal pathogen of many insects and also currently marketed for insect control in yards, gardens, and greenhouses. It produces white muscardine disease, which can cover infected insects with snow-white spores. Another common fungal pathogen of many insects is Metarhizium anisopliae, producing green muscardine disease, referring to the olive-green spores produced by this fungus. Several other fungi infect insects, some of which are also commercially developed, including Isaria fumosorosea and Lecanacillium lecanii. Microsporidia, a type of fungi, tend to cause debilitating infections among insects. Effects are often subtle, such as reduced feeding, activity, or reproduction. Immature stages are usually much more susceptible to infections and survival can be reduced. Spruce budworms and grasshoppers are among the groups of insects that are common hosts of microsporidia parasites. Several Nosema species of microsporidia are also important parasites of honey bees and bumble bees. Nosema locustae can infect developing grasshoppers and is commercially developed for grasshopper control. Many kinds of nematodes develop as parasites of insects. One diverse group are the mermithid nematodes that develop as internal parasites. They may develop slowly in their host, causing debilitating disease that is ultimately lethal. Mermithid nematodes are common in many beetles, mosquito larvae, and some grasshoppers. The largest of the mermithid nematodes one might encounter in a garden is Mermis nigrescens, a parasite of grasshoppers that can be more than 3 inches long. Other nematodes are better described as entomopathogenic nematodes because of their involvement with bacteria. These nematodes always carry insect-killing bacteria with which they have mutual interdependence. The nematodes actively penetrate the body of some insect host, either through natural openings (mouth, spiracles, anus) or by cutting through the exoskeleton. They release the bacteria upon penetration and the bacteria then grow rapidly in the blood (hemolymph) of the insect, killing it within hours to a few days. The nematodes develop on the resulting soup of bacteria and degraded insect tissue. Two genera of entomopathogenic nematodes have been developed as biological controls for insect pests. Various Steinernema species (all contain Xenorhabdus bacteria species) are used to manage insects, including certain caterpillars, fungus gnats, and mole crickets. Infected insects turn tan or gray in color. Heterorhabditis species (all contain Photorhabdus bacteria species) tend to be more effective for control of larvae of white grubs and root weevils in soil. Infected insects turn a red-brown color. Heterorhabditus nematodes are also capable of direct penetration through the host exoskeleton. Another group of large wormlike parasites that affect insects are the horsehair worms. These are placed in a separate phylum from the nematodes (Nematomorpha) and are thicker and darker than Mermis nigrescens, the common nematode parasite of grasshoppers. Horsehair worms have a wider host range and can affect many insects—various crickets and beetles perhaps most commonly. Several species in the genus Gordius may come to the attention of gardeners, particularly near water sources. Eggs of horsehair worms are laid in water, where they hatch. The larvae attach to plants growing in the water and infect insects that ingest them while eating the plants. Subsequently, infections may move to predators that feed on the originally infected insect, such as a ground beetle or mantid that consumes an infected cricket. After the horsehair worm has completed development within the insect host, infected insects ultimately move to water where the mature parasites emerge, then lay eggs. Their occurrence in animal watering troughs is the basis for the common name horsehair worm, as they have a general appearance of an animated horse’s hair.

670

A. Green June beetle grubs infected with Metarhizium anisopliae. DAVID SHETLAR

B. Billbug adult killed by the fungus Beauveria bassiana. DAVID SHETLAR

C. Pea aphid killed by a fungus. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. Mermis nigrescens, the grasshopper

nematode.

JOHN CAPINERA, UNIVERSITY OF FLORIDA

E. A horsehair worm. WHITNEY CRANSHAW

F. Masked chafer grub killed by a

A B

C

D

E

F

Heterorhabditis species of nematode. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

BEES More than 4,000 species of bees are native to North America, and a great many of these may visit garden plantings. All rear their young on pollen and nectar, and many have evolved close relationships with the plants that provide these foods, and the bees providing essential pollination services in return. Most familiar are the bees that form colonies: the honey bee and the bumble bees. These are also truly social insects, which have overlapping generations, provide cooperative care of the young, and divide labor between distinct castes (fertile female queen, sterile female workers, male drones); however, the overwhelming majority of bees are solitary, with all provisioning and care of the young handled by the mother. Bees do possess a stinger, a special modification of the ovipositor—used to lay eggs in other insects—that is linked to venom glands. (Some ants and wasps also have a stinger, and the great majority of insect stings are produced by these insects, including fire ants, yellowjackets, and paper wasps). Bees will sting in defense, usually defense of the colony, and the sting of the social bees can be painful. Solitary bees sting only if handled or accidentally crushed against the skin, and their sting is much less painful. Male bees do not possess a stinger and thus cannot sting, although they may engage in aggressive bluffing behaviors to defend territory.

Honey Bee The honey bee (Apis mellifera)1 is an insect native to parts of Eurasia and Africa that was introduced into North America early, during European colonization in the 1620s. It is an excellent pollinator of many crops and is particularly important for pollinating tree fruits; pollen they return to the hive is carried in special pollen baskets (scopae) on the hind legs. Honey bees also produce large amounts of honey for use as an energy source, and the excess is collected by beekeepers. Honey bees construct nest cells of wax, produced as flakes from special glands on the abdomen, and beeswax is also an important commercial product. Unlike other bees that occur in North America, honey bees maintain perennial colonies. They survive over the winter with an intact colony numbering in the thousands, with the bees clustering together for warmth, feeding on the stored honey and pollen collected the previous season. Although egg laying is suspended for most of the winter months, the queen resumes egg laying in late winter, increasing the population to take full advantage of the nectar flow that comes with spring flowers. At no point can an individual honey bee survive long on its own, and a honey bee colony can be considered a superorganism that functions as a collective unit of all members. Although the fertilized female queen produces eggs, new colonies form when the colony divides through a swarming event. During swarming the majority of the worker bees and the old queen leave the colony and seek to establish a colony in a new location. The workers that remain behind rear a new queen that, after mating, will resume egg laying. Honey bees are nonaggressive when foraging and rarely sting unless their hive is disturbed or they are accidentally trapped or handled. (The great majority of “bee stings” result from the activity of very different insects, usually yellowjacket wasps.) The stinger of worker honey bees is barbed and is pulled out of the bee’s body in the act of stinging, resulting in the bee’s death. 1

Hymenoptera: Apidae

672

A

B A. Honey bee collecting pollen.

C D

SUSAN ELLIS, BUGWOOD.ORG

B. A honey bee strain

of dark coloration. DAVID SHETLAR

C. Honey bee queen

being tended by workers in a colony. JESSICA LOUQUE, SMITHERS VISCIENT, BUGWOOD.ORG

D. Honey bee eggs and young larvae at base of nest cells. JESSICA LOUQUE, SMITHERS VISCIENT, BUGWOOD.ORG

E. Frame from a

honey bee hive showing capped cells containing pupae. WHITNEY CRANSHAW

F. Honey bee swarm. WHITNEY CRANSHAW

E

F

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

BEEs

Bumble Bees Bumble bees (Bombus spp.)1 are large, fuzzy bees brightly colored black with yellow and/or orange. Like honey bees, they are social insects that produce a colony, usually in an abandoned rodent or bird nest where there is insulating material they use to surround the nest. Bumble bee colonies are abandoned at the end of the year, however, and only new, large, fertilized queens survive the winter. The queen establishes a new colony in spring, conducting all chores of foraging, hive construction, and rearing. The first workers produced are usually quite small, but they assist the queen as the colony develops. As the colony grows, worker size tends to increase and some reproductive forms (queens, males) are produced toward the end of the season. Bumble bees are native insects, with close to 50 species in North America. Many are important pollinators, and they have a unique method of acquiring pollen from some plants, known as buzz pollination, which shakes pollen from some kinds of flowers. The collected pollen is then packed into pollen baskets on the hind legs, in a manner similar to honey bees and others in the family Apidae. Bumble bees are used extensively to pollinate greenhousegrown tomatoes, and many native plants are dependent on buzz pollination for seed set. Bumble bees sting readily in defense of their hive but are nonaggressive while foraging. The sting is painful, but the stinger is not left behind. The species of bumble bees one might find in a garden vary with location. Along the Pacific Coast Bombus vosnesenskii (Vosnesensky bumble bee) is common, and in the Pacific Northwest, early in the season, one frequently sees B. melanopygus (blacktail bumble bee). In Texas, B. pensylvanicus (American bumble bee) is one of the more common species in gardens, while in the Rocky Mountain west, B. huntii (Hunt bumble bee) is often observed. Common species in the Mid-Atlantic/New England area include B. impatiens (common eastern bumble bee) and B. bimaculatus (twospotted bumble bee). 1

Hymenoptera: Apidae (Apinae)

Large Carpenter Bees Large carpenter bees (Xylocopa spp.)1 somewhat resemble bumble bees, both in size and in general shape. They can usually be distinguished from bumble bees by having a less hairy abdomen, which often has a metallic blue or green sheen. Large carpenter bees also differ by being a solitary species, although it is common for several nests to be built in close proximity or two females using the same opening. As the name may imply, large carpenter bees typically create nests in wood, which they can tunnel deeply. Dead limbs, logs, and stems of large plants serve as nest sites in natural areas; however, unfinished structural wood, usually coniferous softwoods such as pines, cedar, and juniper, is commonly used by the eastern carpenter bee (Xylocopa virginica). Tunneling can be extensive, typically extending 1–1½ feet, going primarily with the grain. The tunnel is then used to create a series of nest cells, each provisioned with nectar and pollen, separated by partitions of chewed wood. Both males and females pack themselves into old burrows to overwinter. Woodpeckers will often peck out these bees from infested wood during the winter. Females are not aggressive and very rarely have been known to sting; however, the males often make threatening types of flights to defend territory, and these actions often cause alarm. This is purely a bluffing behavior, as the males cannot sting nor will they bite. In addition to this behavior, males of many species, including the eastern carpenter bee, can be identified by a patch of yellow or white hair on the front of the head. 1

Hymenoptera: Apidae (Xylocopinae)

674

A D

B

C

E

F

G

A. Bumble bee (left) and honey bee (right). WHITNEY CRANSHAW

B. Nest of Bombus vagans. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

C. Bumble bee collecting

pollen.

DAVID SHETLAR

fraternus.

JOHNNY N. DELL, BUGWOOD.ORG

E. Bumble bee, Bombus

vosnesenskii.

WHITNEY CRANSHAW

F. Carpenter bee at nest entrance. JIM KALISCH, UNIVERSITY OF NEBRASKA

I

queen (left) and workers of Bombus huntii. WHITNEY CRANSHAW

H. Carpenter bee leaving nest. DAVID SHETLAR

I. Carpenter bee at flower.

D. Bumble bee, Bombus

H

G. Range of size between

J

SUSAN ELLIS, BUGWOOD.ORG

J. Male carpenter bee

showing white facial marking. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

BEEs

Cavity-nesting Bees Several kinds of solitary bees nest in cavities, either ones that naturally exist (e.g., old wood borer holes, hollow canes or tubing, areas of loose bark, crevices in stones) or ones they excavate from decaying wood or the pith of plants. Perhaps best known of these are the leafcutter bees (Megachile spp.),1 a large group of bees represented by some 140 North American species. Many have developed specialized associations with specific plants, usually in either the pea or aster families; a European species, M. rotundata (alfalfa leafcutter bee) is widely used in the pollination of alfalfa grown for seed. Leafcutter bees and other bees in the family Megachilidae (mason bees, carder bees) carry pollen on the underside of the abdomen. Once a suitable cavity has been located or constructed, the mother bee will then cut a series of leaf fragments that are used to construct a nest cell. It is then provisioned with enough pollen and nectar to support a single larva, then capped with a few more circular leaf fragments. The process is then repeated, and a series of cells may be produced within a cavity. The larvae consume the food and rapidly develop but then remain in a dormant condition, usually surviving through winter as full-grown larvae and then pupating the following spring. Leafcutter bees produce one generation per year. Another species-rich group of cavity nesting bees are mason bees (Osmia spp.),1 with 150 North American species, most in the western regions. Most mason bees have some sort of metallic coloration (green, blue, purple) and lack bands or other conspicuous markings. Nest cells they produce are usually separated with plugs of mud, although some species use chewed plant matter in nest construction. One species, the blue orchard mason bee (O. lignaria), is commercially distributed and can be useful for helping to pollinate early flowering plants, such as orchard crops. Hoplitis1 species are also sometimes known as mason bees, and these may resemble Osmia, although most (but not all) lack metallic coloration and are often black. They may also use similar nest sites but divide cells with a wider variety of materials, including soil and tiny pebbles, chewed wood, and leaves. Almost all Hoplitis spp. occur in western North America. The small carpenter bees (Ceratina spp.)2 are pith-nesting bees, creating tunnels in the pith of plants exposed by breakage or pruning cuts. Rose, caneberries, butterfly bush, sumac, and other pithy plants are commonly used for establishing nest sites. A series of nest cells are created, separated by chewed pith. After nests are completed the female typically remains at the nest entrance and dies there, further sealing the entrance. The bees mature in later summer but do not emerge until the following year. Most small carpenter bees are about ⅓ inch long and shiny black, blue, or green. They may superficially resemble several other small bees, particularly some of the sweat bees; however, they can be distinguished by a cylindrical abdomen that terminates in a tiny point. A wide variety of cavities are used by the carder bees (Anthidium spp.),1 which can nest in soil, among rocks, or in plant stems. Plant hairs are used for lining nests by these bees, and they are thus often found near hairy leaved plants such as mullein (Verbascum) and lamb’s-ear (Stachys). Most native species occur in the southwest, but a European species, A. manicatum (wool carder bee), is spreading widely through the continent. Males of the wool carder bee will aggressively defend territory, and they can kill other bees by puncturing them with spines they have on the underside of the abdomen. 1

Hymenoptera: Megachilidae; 2 Hymenoptera: Apidae (Xylocopinae)

676

A

B

C

E

D

F

G H

J

I

A. Leafcutter bee visiting daisy flower. JIM KALISCH, UNIVERSITY OF NEBRASKA

B. Leafcutter bee with pollen carried on underside of abdomen. DAVID SHETLAR

C. Leafcutter bee removing cut leaf fragment. DAVID SHETLAR

D. Leafcutter bee pollinating sweet pea. WHITNEY CRANSHAW

E. Blue orchard mason bee, Osmia lignaria. SCOTT BAUER, USDA AGRICULTURAL RESEARCH SERVICE

F. Mason bee nesting in drilled wood block. WHITNEY CRANSHAW

G. Small carpenter bee. TOM MURRAY

H. Small carpenter bees reared within raspberry cane. BOB HAMMON, COLORADO STATE UNIVERSITY

I. Wool carder bee at flower. WHITNEY CRANSHAW

J. Wool carder bee male. JIM KALISCH, UNIVERSITY OF NEBRASKA

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

BEEs

Soil-nesting Bees The great majority of solitary bees nest in soil. Typically a central tunnel will be dug, and along the sides or at the end of the tunnel a series of chambers will be constructed. Each will be provisioned with sufficient pollen and nectar to support one bee, which will complete its development in the chamber. Characteristics such as soil type, slope, drainage, exposure to sun, and vegetation cover are important in determining the suitability of a specific site for the various ground-nesting bees. Almost all create individual nests, although a few species will sometimes share the main tunnel and nest entrance; however, very favorable sites may support large numbers of bees all nesting in close vicinity. The cavity-nesting species, like all solitary bees, are not aggressive and will sting only if handled. Furthermore, the sting of almost all solitary bees is much milder than that of the social, colony-producing honey bee and bumble bees. Several genera (Melissodes, Eucera, Svastra)l of ground-nesting bees are known as “long-horned bees” because of the particularly long antennae of the males. They are densely hairy, and larger species have a robust body form that may approach that of a bumble bee. The majority create vertical burrows in flat ground, which they line with a waxlike material. Those that nest in cut banks make a horizontal burrow. Aster family plants, particularly sunflowers, are most commonly used, and these bees carry the pollen in pollen baskets. Digger bees (Anthophora spp., Habropoda spp.)1 are also quite hairy bees, with most species found in western states. They nest in flat or gently sloping areas of soil. Most prefer lighter soils (loam, sandy loam) and they sometimes will nest in sandboxes and sandy play areas. Anthophora females have very hairy hind legs and often have bands on the abdomen. Habropoda are usually gray, but heavy-bodied in a manner resembling bumble bees, and some similarly will buzz pollinate flowers they visit. The squash bees (Peponapis spp.)1 are specialists of cucurbit flowers. Males spend the night in flowers, and most flower visits occur in early morning, shortly after blooms open. They will typically nest in areas where there is patchy vegetation, sometimes in the very near vicinity of the cucurbit plants they visit. Plasterer bees (Colletes spp.)2 are moderate-sized bees (⅓–½ inch), hairy-bodied with bands of hairs on the abdomen. They line their soil burrows with a cellophane-like material they secrete from special glands, and the young are provisioned with a largely liquid mass, in contrast to the semisolid pollen/nectar mixtures provided by most other solitary bees.

678

A C B

D

E

F A. Soil mounds produced by ground nesting bees. WHITNEY CRANSHAW

B. A Melissoides species of longhorned bee. JIM KALISCH, UNIVERSITY OF NEBRASKA

C. A Svastra species of longhorned bee. JIM KALISCH, UNIVERSITY OF NEBRASKA

D. An Anthophora species of digger bee. KEN GRAY COLLECTION, OREGON STATE UNIVERSITY

E. Squash bees in squash blossom. WHITNEY CRANSHAW

F. A plasterer bee at nest entrance. DAVID SHETLAR

Natur al ENEmiEs of iNsEcts aNd PolliNators: thE “BENEficial Bugs”

BEEs Mining bees (Andrena spp.)3 comprise one of the largest single groups of solitary bees that occur in North America, with more than 400 species. They are small to moderate in size (⅓–⅔ inch), typically dark colored (black, blue, green), with bands on the abdomen. The hind legs of females are very hairy and used to collect pollen, including the upper segments. Mining bees will usually be seen nesting in sandier soils, often under the cover of a plant. The “sweat bees” (Halictidae) are also a species-rich bee family, with more than 500 North American species. Some are very brightly colored metallic green, notably those in the genera Agapostemon and Augochlorella, but most have more muted coloration, such as gray-and-white banding. Sweat bees visit a wide variety of crops, particularly those with relatively small flowers. Pollen is carried on the hind legs. Almost all are ground-nesting species. One group important in the pollination of plants in parts of the western U.S. are the alkali bees (Nomia spp.),4 and these prefer saline soils for nesting. One species, N. melanderi, is actively promoted by many alfalfa seed growers as a particularly effective pollinator of the crop, and growers will sometimes create sites that are suitable for nesting. The name “sweat bee” refers to the habit of some, specifically in the genera Lasioglossum and Halictus, to be attracted to human sweat. This habit sometimes results in stings when they are swatted, but the sting is very mild. Most sweat bees, including the bright, metallically colored green sweat bees (Agapostemon spp.),4 are actually not attracted to sweat. 1

Hymenoptera: Apidae (Apinae); 2 Hymenoptera: Colletidae; 3 Hymenoptera: Andrenidae;

4

Hymenoptera: Halictidae

Halictus sweat bee at nest entrance. DAVID SHETLAR

680

Andrenid bee leaving nest.

Sweat bee pupae exposed from soil cells. DAVID SHETLAR

WHITNEY CRANSHAW

A

B C

D E

A. An andrenid bee. SUSAN ELLIS, BUGWOOD.ORG

B. Andrenid bee at nest entrance. DAVID SHETLAR

C. An Agapostemon species of sweat bee. WHITNEY CRANSHAW

D. Sweat bee. JIM KALISCH, UNIVERSITY OF NEBRASKA

E. A Lasioglossum species of sweat bee. DAVID SHETLAR

GLOSSARY abdomen Posterior of the three main body divisions in an insect; posterior of the two main body divisions in a mite, spider, or other arachnid. adelgid Family of “woolly” aphids (Adelgidae) that develop on conifers. aestivation Temporary dormancy induced by warm and/or dry conditions. alate With wings. Forms of aphids with wings in the adult stage are known as alatae. alternate host Plant required to complete the life cycle of an insect or fungus, in addition to the host plant that is primarily damaged. The habit of using an alternate host is common among certain groups of aphids and the rust fungi. annual Plant or fungal fruiting body that persists in an active, living state for only one season. apterous Without wings. Forms of aphids without wings in the adult stage are known as apterae. asexual Any type of reproduction not involving a union in which fertilization and meiosis occur. ballooning A means that allows some spiders, mites and insects to become airborne through release of silk threads to catch wind currents. biennial Plant that takes two seasons to complete its life cycle. Growth during the first year is vegetative, and flowering structures are produced the second year. brambles Rose family plants of the genus Rubus that produce small fruit on prickly canes, including raspberries and blackberries. The term is often used interchangeably with caneberries. brassicas Cultivated plants in the genus Brassica, which includes broccoli, cabbage, cauliflower, Brussels sprout, mustard, collard, canola, and other plants. broadleaf Plant having broad leaves rather than needlelike or scalelike leaves. Most cultivated garden plants are broadleaf except grasses and conifers. bud break Time at which dormant buds begin expanding and opening. callus Mass of thin-walled undifferentiated cells that often develops on plants as the result of wounding. calyx Outer whorl of sepals that group together in a flower. On apple, the calyx end is at the tip of the fruit, opposite the stem end. cambium Layer of cells between the bark and wood that divides into phloem outward and xylem (wood) inward. If destroyed or exposed, the plant dies.

caneberries Rose family plants of the genus Rubus that produce small fruit on prickly canes, including raspberries and blackberries. The term is often used interchangeably with brambles. caterpillar Larva of a butterfly, moth, or sawfly. catfacing Dimpling of fruit produced by injury during early development. It may result from feeding by various insects with sucking mouthparts, from egglaying wounds, or from surface chewing of young fruit. chelicerae The first pair of appendages of an arachnid used as the mouthparts. Different forms of chelicerae occur among the various arachnids, including ones that are hollow and terminate in a fang, often used to inject toxin, scissorlike to capture and cut prey, or fashioned to tear food. chenopods Plants in the goosefoot, pigweed, or beet family of plants, Chenopodiaceae. Common chenopods include beet, spinach, lambsquarter, pigweed, and amaranth. chlorosis Yellowing of normally green tissue caused by chlorophyll destruction or failure of chlorophyll formation. Tissues that show chlorosis are described as being chlorotic. chrysalis (pl. chrysalides) Pupal stage of a butterfly. It is not covered with silk and often contains spines and patterned colors. Altenatively known as a chrysalid (pl. chrysalids). cocoon Silken case in which the pupal stage of many insects is formed and metamorphosis to adult stage occurs. cole crops Cultivated vegetables in the mustard/cabbage family, Brassicaceae. This includes broccoli, cabbage, Brussels sprout, cauliflower, radish, turnip, and other plants. These are also sometimes known as crucifers. complete metamorphosis Pattern of metamorphosis exhibited by many insects (e.g., beetles, moths and butterflies, sawflies, flies) that involves eggs, followed by immature larvae, a transition pupal stage, and finally adults. Adult and immature stages of insects that exhibit complete metamorphosis often have very different habits and appearances from each other. Also called holometabolous metamorphosis. composites Plants in the sunflower family, Compositae (also known as the aster family and formerly called Asteraceae). 682

GLOSSARY conifer General term for cone-bearing plants; it includes pine, cypress, juniper, spruce, arborvitae, and yew. cornicle Tubular structure (paired) on the posterior of aphids through which alarm pheromones are released. crawler First stage after egg hatch of a scale or mealybug; it is the most dispersive form of the insect. crochets Hooks found on the tip of the prolegs of moth and butterfly larvae. crucifers Cultivated plants in the mustard family, Brassicaceae, formerly Cruciferae. This includes broccoli, cabbage, Brussels sprout, cauliflower, radish, turnip, and other plants. Also called brassicas and cole crops. cucurbits Plants in the squash or gourd family, Cucurbitaceae. Cultivated plants include squash, pumpkin, cucumber, melon, and gourds. cuppressaceous conifers Plants in the cypress family, Cuppressaceae, which includes cypress, juniper, baldcypress, arbovitae, and other conifers with flattened or scalelike needles. cyst A stage encapsulated in a protective membrane. Cysts may be produced to allow an organism to survive during periods of adverse environmental conditions. deciduous Referring to a plant that annually sheds its leaves. defoliation Loss of leaves, as occurs in natural shedding or from the feeding activities of insects and other plant feeders. deutogyne Overwintering form of an adult female eriophyid mite. deutonymph Third and final immature stage of a mite or tick. diapause Period of dormancy many insects undergo to avoid adverse conditions (e.g., winter cold). Diapause is more involved than simple dormancy or hibernation and can be terminated only by certain stimuli such as day length or a prescribed length of exposure to cold. dieback Decline and dying of the upper or terminal growth of a plant. disease Any malfunctioning of host cells and tissues that results from continuous irritation by a pathogenic agent or environmental factor and leads to development of symptoms. disease cycle Chain of events involved in disease development, including the stages of development of the pathogen and the effect of the disease on the host. domatia Areas of dense plant hairs at the junction of leaf veins. A speculated function of these sites is to provide protection to predatory mites.

dorsal Referring to the back or upper side. ectoparasitoid An insect that develops within another insect and ultimately kills its host. endoparasitoid An insect that develops on the outside of another insect and ultimately kills its host. epidermis Outermost layer of cells of leaves, young stems, roots, flowers, fruits, and seeds. In insects the epidermis is the single outermost layer of cells that secretes the protective cuticle. erineum (pl. erinea) A felty patch on a leaf surface, caused by a change in plant growth, or gall, where plant hairs are produced in great abundance. Many eriophyid mites cause such changes in leaf growth. eriophyids Mites in the superfamily Eriophyoidea, which have two pairs of legs and a generally elongate body form, are minute in size, and usually feed on plants. exoskeleton Skeletal structure formed on the external surface of an animal, as occurs with insects, mites, and other arthropods. exuviae Discarded exoskeleton of an arthropod after a molting event. eyespots Prominent markings resembling eyes on the wings or body of certain insects. family Taxonomic subgroup of organisms within an order. For example, lady beetles and sap beetles are two families found in the order Coleoptera, the beetles. Each family, in turn, is subdivided into genera. The scientific names of animal families end in the suffix -idae. fascicle A bundle of leaves or needles growing closely together. For example, needles of pines grow in fascicles of 2–5 needles, with a sheath at the base. fingergalls Abnormal growth forms in the shape of fingers, such as are produced by eriophyid mites on certain plants (e.g., wild plum, cherry). flagging Yellowing or wilting of foliage on a single branch. forewings Pair of wings closest to the head of an insect. frass Solid insect excrement, typically consisting of a mixture of chewed plant fragments. fundatrix Female aphid emerging from the overwintered egg that initiates colonies in spring. gall Abnormal growth of plant tissues, caused by the stimulus of an animal, microorganism, or wound. genus (pl. genera) A group of species that have very similar characters and are presumed to have the same, recent common ancestry; the taxonomic rank below family and above species. 683

GLOSSARY girdling Removal of tissue all around a stem or branch so that movement of water and nutrients is interrupted. gradual metamorphosis See simple metamorphosis. gregarious Living and feeding in groups. grub Immature form of many beetles. hemimetablous Referring to a type of simple metamorphosis found among some aquatic orders of insects (dragonflies, stoneflies, mayflies) in which the winged adult is quite different in form from the aquatic nymph. herbaceous Referring to plants that lack woody tissues and annually die back. hibernaculum (pl. hibernacula) Tiny cocoon spun by first- or second-instar caterpillars as overwintering shelter. hibernation Winter dormancy. honeydew Sugary, liquid excrement produced by certain aphids, scales, and other insects that feed in the phloem of plants. host Plant on which an insect or pathogen feeds; animal on which a parasite or parasitoid develops. hypopus (pl. hypopi) Nonfeeding stage produced by some mites during development, often in response to adverse environmental factors. in copula Act of being physically coupled during mating. injury Damage to a plant by an animal, physical, or chemical agent. inoculum Fungal spores, mycelium, bacterial cells, or viral particles that can initiate infections. instar Stage of an insect between periods when the skin is shed. internode Region between two adjacent nodes on a stem. invertebrate An animal that lacks a backbone. Insects, other arthropods, slugs and snails, and earthworms are examples of invertebrates IPM—integrated pest management Term applied to a philosophy of managing pests that incorporates proper identification of problems and assessment of potential injury before taking management actions. Management typically involves several approaches (e.g., biological, cultural, chemical) used in a complementary, integrated manner. Consideration is also given to environmental and social impacts of pest management activities. June drop Natural shedding of fruit that occurs after fruit set. The term is usually applied to tree fruits, particularly apples.

larva (pl. larvae) Immature form, between egg and pupa, of an insect with complete metamorphosis, i.e., caterpillar, maggot, or grub. Also the first immature stage of a mite or tick, which is six-legged. lateral Referring to the side. Used to describe location of markings on an insect. leafminer Insect that develops by feeding on internal leaf tissues which it chews as it mines the leaf. An insect that tunnels needles in a similar manner is called a needleminer. lenticel Small pore (natural opening) on a stem, tuber, root, or fruit through which carbon dioxide and other gases pass. lerp Wax-covered sugary excrement produced by some insects that suck sap, notably psyllids. lesion Localized, often sunken, area of diseased or disordered tissue; a wound. macrodecomposer A large organism, easily visible, that consumes wastes or dead and decaying organisms. By consuming large particles of this material macrodecomposers may function to accelerate further decomposition by microbial decomposers, such as fungi and bacteria. Earthworms, millipedes and many insects are examples of macrodecomposers. maggot Immature form of many true flies (Diptera). mandible Portion of the insect mouthpart that is usually prominent and highly hardened. In insects that chew, it is the primary structure used to cut and grind. In insects with sucking mouthparts, it penetrates tissues. Mandibles are paired in insects except in thrips, which have only one. marsupium Structure found in some animals in which immature stages continue development after birth. maxilla Portion of the insect mouthpart located immediately below the mandible. In insects that chew, it is used to manipulate food. The paired maxillae (plural) form the feeding tube for most insects that suck fluids. meconium Waste material excreted by an adult insect following emergence from the pupal stage. mesophyll Parenchyma cell tissues in a leaf or other part of the plant underneath the epidermis. Photosynthesis occurs in the mesophyll. metamorphosis Changes in form that take place during stages of animal development. mine To form a burrow or excavate a tunnel. Used to describe the activities of insects that live or feed in a leaf or needle. molt Shedding of the exoskeleton by an insect in the process of development.

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GLOSSARY mosaic Symptom of certain viral diseases of plants, characterized by patches of normal color intermingled with patches that are light green or yellowish. mucus Viscous secretion used to protect tissues, primarily from drying. mustard family The plant family Brassicaceae. Other names include cabbage family or crucifers mutualistic Benefiting both species that are in some association. necrotic Dead and discolored. needle sheath Protective structure at the base of needles. neem A term used to describe materials (azadirachtin, oils) extracted from seeds of the neem tree (Azadirachta indica) that have insecticidal uses. nematode Generally microscopic, wormlike animals that live saprophytically in water or soil or as parasites of plants and animals. nidus A small nest of plant material created by some insects (e.g., leafrolling weevils) within which the larvae develop nightshade family The plant family Solanaceae. node Enlarged joint on a stem which is usually solid; site from which a leafy bud and branch arise. notching Angular, often nearly rectangular, cuts along a leaf edge, characteristic of insects such as root weevils. nymph Immature stage of an insect with simple metamorphosis (e.g., aphids, bugs, grasshoppers). omnivore Animal that feeds on a wide variety of materials, including animal products and plants. order Taxonomic subgroup of organisms found within a class. For example, beetles are an order of insects, the Coleoptera. osmeterium (pl. osmeteria) Fleshy Y-shaped gland extended by swallowtail larvae in response to disturbance. overwinter To spend the winter. oviparae Egg-producing form of an aphid, which appears at the end of the growing season. oviposit (v.), oviposition (n.) Act or process of laying an egg by an insect. ovipositor Egg-laying structure of a female insect. ovisac Large waxy sac into which eggs are laid by mealybugs, some soft scales, and related insects. parasite Organism that lives at the expense of another. parasitoid Organism that develops internally, rarely externally, on a host and ultimately kills it. parenchyma Thin-walled plant cells, capable of division, which make up much of a plant’s tissues, exclusive of those involved primarily in structural support or

nutrient transport. Photosynthesis and storage are functions of parenchyma cells. parthenogenesis Reproduction in which an unfertilized egg develops into an individual. pathogen Entity that can incite disease. paurometabolous Referring to insects that undergo simple, or gradual, metamorphosis, where the adult and immature stages have similar habits and transition in form is gradual, with the adults usually winged. perennial Plant or fungal fruiting body that persists in an active, living state for more than one growing season. petiole Leaf stem or stalk that attaches to a twig. pheromone Chemical used to communicate between members of the same species. For example, many female moths produce sex pheromones to attract mates. phloem Food-conducting tissue located in the bark of woody plants consisting of sieve tubes, companion cells, phloem parenchyma, and fibers. photoperiod Relative amount of time during the day that is light (or dark). phylum (pl. phyla) One of the highest ranks in the system of classification of living organisms. Arthropoda, which includes insects, arachnids, millipedes, and other animals, is an example of a phylum, which is subdivided into classes. Ranked above phylum is kingdom.. phytoplasma A specialized group of bacteria that lack a cell wall and develop in the phloem tissues of plants. pitch Resinous material exuded by conifers, either naturally or in response to a wound. Populus Genus of plants that includes poplar, cottonwood, and aspen. predator Animal that moves and hunts smaller animals. prepupa Period during the last larval stage, prior to pupation, when insects undergo changes in behavior and sometimes form. prey Animal that is hunted and killed for food. primocane Biennial cane of a caneberry, or bramble, in the first year of growth, before flowering occurs. proleg Fleshy leglike extensions of the abdomen found on the larval stages of sawflies and on caterpillars, the larvae of moths and butterflies. pronotum Upper surface of the first segment of the thorax, located immediately behind the head. prothorax First segment of the thorax. protogyne Form of a female eriophyid mite that occurs during the growing season (vs. overwintering form).

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GLOSSARY protonymph Second immature stage of a mite or tick. Prunus Genus of plants known as stone fruits; it includes peach, plum, cherry, almond, and related plants. pupa Transitional stage, between larva and adult, of insects with complete metamorphosis. pyrethroids A group of synthetically manufactured insecticides chemically derived from the pyrethrins found in the pyrethrum daisy. Permethrin, bifenthrin, cyfluthrin, resmethrin, and esfenvalerate are common types of pyrethroid insecticides. pyrethrum Insecticide derived from dried and ground flowers of the daisy Tanacetum cinaeriafolium, which contain active insecticidal compounds known as pyrethrins. receptacle Enlarged tip of a flower on which the flower parts are borne. On raspberries and related plants, the receptacle is the elongated base where the berry fruits are attached. resin Sticky compound produced by plants, especially conifers. resistance Ability of an organism to exclude or overcome, completely or in some degree, the effect of a pathogen, insect, or other damaging factor. rosaceous plants Plants in the rose family, Rosaceae, including many commonly grown trees and shrubs such as rose, stone fruits, apple and pear, mountainash, cotoneaster, pyracantha, brambles, amelanchier, and hawthorn. russeting Bronzy and somewhat thickened surface of a fruit or leaf induced by certain mites and other causes. saprophyte Organism that feeds on dead organic matter, commonly causing its decay. sap wells Holes produced in plants by sapsuckers and other birds to produce a flow of sap on which they feed. These holes are sometimes mistaken for the activity of wood-boring insects. sapwood Young, physiologically active zone of wood; outermost growth layers of xylem in woody plants that conduct water. scorch Damage to leaf margins resembling a burn, resulting from infection or unfavorable environmental conditions. Feeding injuries produced by certain sucking insects may cause scorch symptoms. scutellum Plate on the back of the middle segment of the thorax, often of triangular form. It is quite large and distinctive in insects such cicadas, stink bugs, and some beetles. secondary agent Any infection or infestation agent that results from a primary stress agent.

serpentine Winding, twisting pattern, typically used to describe the shape of certain leaf mines. sexual Produced as a result of a union in which fertilization and meiosis occur. shepherd’s crook Type of injury in which newly produced plant shoots wilt and curl. shoot strike Terminal dieback of a plant caused by tunneling of some insect larvae. shotholes Small holes in leaves. These are most characteristics of flea beetles and some other insects that chew pits in the interior of leaves. simple metamorphosis Pattern of metamorphosis exhibited by many insects (e.g., true bugs, aphids, grasshoppers, earwigs) that involves eggs, followed by immature nymphs, and finally adults. Adult and immature stages usually feed in the same manner and are primarily differentiated by the adult features of sexual maturity and (usually) wings. Also called gradual metamorphosis. Insects with this life cycle are also referred to as being paurometabolous. skeletonize Feeding pattern of certain leaf-feeding insects that avoid feeding on larger veins of the leaf, producing a lacy “skeleton” of the leaf. solanaceous Referring to a member of the nightshade family of plants, Solanaceae. This family includes many cultivated plants, among them petunia, potato, tomato, pepper, nightshade, and nicotiana. solitary Living alone, not in groups. sooty mold Dark, typically black fungus growing on insect honeydew. sp. Species in the singular; spp. refers to two or more species. spiderling Newly hatched spider. spinnerets External structures used to spin silk. These occur at the tip of the abdomen in spiders and near the mouth in caterpillars. spinosad Insecticide derived from exudates of the soil microorganism Saccharopolyspora spinosa. The active compounds are known as spinosyns. spiracle Opening in the body through which arthropods breathe. spore Reproductive unit of fungi, consisting of one or more cells. It is analogous to the seed of green plants. spumaline A sticky coating produced by some insects, such as tent caterpillars, to cover and protect the egg mass. stabilimentum Thick band of silk, often laid in a zigzag pattern, produced in the center of webs by some orbweaving spiders.

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GLOSSARY tent Protective shelter constructed of silk, spun by certain caterpillars. terminal growth Typically refers to new growth or buds at the end of a branch or twig. test Waxy covering (exuviae) produced by a scale insect. thorax Middle area of an insect body, where the legs and wings are attached. It is subdivided into three body segments: the prothorax, mesothorax, and metathorax. toxin Poisonous secretion produced by a living organism. tubercles Rounded protuberances found on many insects, particularly caterpillars. uropod The last pair of appendages on the abdomen of a crustacean. vector Living organism (i.e., insect, bird, higher animal, etc.) able to carry and transmit a pathogen. ventral Referring to the underside of the body. virus Submicroscopic obligate parasite consisting of nucleic acid and protein. windowpaning Chewing of leaves such that all the tissues are removed except one layer of the epidermis, producing a translucent “window.” wingspan Measurement between tips of the extended forewings of an insect. witches’-broom Broomlike growth or massed proliferation caused by the dense clustering of branches of woody plants. “woolly” aphids Aphids that produce large amounts of wax in the form of strands that cover the body. They are most commonly found in the subfamily Pemphiginae. The closely related pine and spruce aphids (Adelgidae) are often also considered “woolly” aphids. xylem The complex supporting and water- and mineralconducting tissue of vascular plants that makes up the sapwood and heartwood.

stippling Small, white flecking injuries on foliage produced by certain insects (some leafhoppers, lacebugs) and spider mites, resulting from removal of plant sap. stone fruits Plants that produce a fleshy fruit with a pit and that are found in the genus Prunus. They include cherry, apricot, peach, and plum. stylet When applied to insects, a reference to mouthparts designed to penetrate and suck fluids. In Hemiptera and Homoptera, the stylet bundle consists of paired mandibles and maxillae that are extremely elongate and fine. subfamily Subgrouping of organisms that occur in a single family but share features different from another subgrouping in the same family. The scientific names of animal subfamilies end in the suffix -inae. superfamily Grouping of several families of an organism within an order that share features different from another grouping of families in the same order. The scientific names of animal superfamilies end in the suffix -oidea. susceptible Lacking the inherent ability to resist disease or pesticides. symbiont Organism living together with another, larger, dissimilar organism. symptom External and internal reactions or alterations of a plant as a result of a infestation by insects, pathogens, other outside agents, or environmental conditions. systemic Spreading internally throughout the plant body; said of a pathogen or chemical. systemic insecticide An insecticide is capable of moving internally through a plant. Systemic insecticides may be sprayed on leaves, applied to soil, or injected; they move from the point of application. Acephate and imidacloprid are examples of systemic insecticides.

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INDEX 24-spot lady beetle 204 Abbot’s bagworm 116 aberrant wood borer 444 Abgrallaspis ithacae 272 acacia psyllid 280 Acalitus fagerinea 333 Acalitus neoessigi 606 Acalitus vaccinii 320, 333, 606 Acalymma trivittatum 174, 484, 564 Acalymma vittatum 174, 484, 564 Acanalonia bivitatta 400 Acanthocephala declivis 604 Acanthocephala femorata 604 Acanthocephala terminalis 604 Acantholyda erythrocephala 152 Acaraspis erinacei 234 Acarus siro 536 Aceria aceris 333 Aceria aloinis 333 Aceria baccharices 332 Aceria caryae 332 Aceria caulis 333 Aceria elongatus 333 Aceria erineus 332 Aceria fraxiniflora 606 Aceria malherbae 332 Aceria modestus 333 Aceria negundi 332 Aceria neobeevori 606 Aceria parapopuli 333 Aceria parulmi 332 Acericesis ocellaris 238 Achatodes zeae 344 achemon sphinx 70 Achyra rantalis 126 Acizzia uncatoides 280 Acleris semipurpurana 128 Acmaeodera spp. 568 Acossus centerensis 428 Acossus populi 428 acrea moth 92 Acrobasis demotella 344 Acrobasis indigenella 120 Acrobasis juglandis 118 Acrobasis nuxvorella 552 Acrobasis tricolorata 552 Acrobasis vaccinii 552 acrobat ants 524 Acrolophus spp. 496 acorn weevils 574 Acronicta americana 88

Acronicta leporina 88 Acronicta lepusculina 88 Acropteroxys gracilis 362 Acrosternum hilare 596 Actias luna 80 Aculops cannibicola 320 Aculops fuchsiae 332 Aculops gleditsiae 320 Aculops lycopersici 320 Aculops massalongoi 320 Aculops pelekassi 606 Aculops tetanothrix 332 Aculops toxicophagus 332 Aculus fockeui 320 Aculus ligustri 320 Aculus schlectendali 320, 606 Acyrthosiphon lactucae 256 Acyrthosiphon pisum 256 Adalia bipunctata 610 Adelges abietus 422 Adelges cooleyi 422 Adelges piceae 370 Adelges tsugae 370 adelgids 370, 422 Admes spider mite 314 Aeolothrips spp. 628 aerial yellowjacket 588, 656 African fig fly 582 agave weevil 448 Agelenopsis spp. 646 Agrilus angelicus 348 Agrilus anxius 432 Agrilus arcuatus 348 Agrilus bilineatus 436 Agrilus coaxalis 436 Agrilus corylicola 348 Agrilus cuprescens 348 Agrilus cyanescens 348 Agrilus difficilis 436 Agrilus granulatus granulatus 436 Agrilus granulatus liragus 436 Agrilus granulatus populi 436 Agrilus planipennis 434 Agrilus politus 436 Agrilus prionurus 436 Agrilus quercicola 436 Agrilus ruficollis 348 Agrilus sinuatus 436 Agrilus torquatus 348 Agrioconota bivittata 181 Agriphila ruricolella 124 Agriphila vulgivagella 124 Agrius cingulata 72

Agromyza aristata 224 Agromyza parvicornis 222 Agrotis ipsilon 492 Agrotis subterraneana 98 ailanthus webworm 144 Alabama jumper 540 Albuna fraxini 490 Albuna pyramidalis 490 alder beadgall mite 332 alder borer 442 alder flea beetle 190 alder flea weevil 200 alder spittlebug 398 Alebra albostriella 286 Aleochara bilineata 616 Aleurocanthus woglumi 246 Aleurodicus dugesii 246 Aleurodicus rugioperculatus 246 Aleurothrixus floccosus 246 Aleyrodes proletella 246 Aleyrodes spiraeoides 246 alfalfa caterpillar 56 alfalfa leafcutter bee 168, 676 alfalfa looper 102 alfalfa webworm 126 alfalfa weevil 200 alkali bees 680 Allacinctus nigritibialis 160 Allacinctus viennensis 160 Allantus cinctus 160, 346 Allokermes galliformis 394 Allonemobius fasciatus 46 Allonemobius socius 46 aloe mite 333 Alsophila pometaria 104 Altica chalybea 190 Altica foliacea 190 Altica ignata 190 Altica torquata 190 Alypia octomaculata 100 Amauromyza parvicornis 222 Amauronematus azalae 158 Amblyptilia pica 556 Amblyseius fallicius 650 ambrosia beetles 460–463 ambush bugs 630 American cockroach 54 American dagger moth 88 American foulbrood 668 American hornet moth 488 American house spider 644 American lotus borer 136 American plum moth 430

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American serpentine leafminer 214 Ametastegia pallipes 160 Amorpha juglandis 70 Ampeloglypter ater 352 Ampeloglypter sesostris 352 Amphibolips confluenta 234 Amphibolips nubilipennis 234 Amphibolips quercusspongifica 234 Amphicerus bicaudatus 353 amphipods 532 Amphipyra pyramidoides 560 Amyelois transitella 554 Amythas diffringens 540 Amythas hawayanus 540 Amythas higendorfi 540 Amythas hupeiensis 540 Anagrapha falcifera 102 Anaphothrips spp. 306 Anarsia lineatella 344, 554 Anasa armigera 292 Anasa tristis 292, 604 Anasa wilt of cucurbits 293 Anastrepha ludens 578 Anatis mali 610 Ancylis comptana fragariae 134 Ancylis platanana 134 Andricus lasius 234 Andricus palustris 234 andromeda lace bug 302 Anephalus parallelus 354 Anephalus villosus 354 angulate lace bug 302 Anisandrus dispar 462 anise swallowtail 60 Anisomorpha buprestoides 50 Anisomorpha ferruginea 50 Anisota senatoria 82 Anisota stigma 82 Anodiella aurantii 392, 604 Anodiella citri 604 Anomis erosa 100 Anoplophora glabripennis 444 Antheraea polyphemus 80 Anthicus spp. 566 Anthidium manicatum 676 Anthonomus consors 570 Anthonomus eugenii 572 Anthonomus quadrigibbus 570 Anthonomus signatus 570 Anticarsia gemmatalis 100 antlike flower beetles 566 ant-like gallfly 234

INDEX antlions 622 Antonia graminis 264 Antonia pretiosa 264 Antron douglasii 234 ants 518–525, 654 Anurogryllus arboreus 514 Apamea devastator 496 aphelinid wasps 664 aphid parasitoids 662 aphid predator midge 624 Aphidoletes aphidimyza 624 aphids 248–259, 322–323, 526–529 Aphis armoraciae 256 Aphis caenothi 256 Aphis citricola 252 Aphis craccivora 257 Aphis fabae 252 Aphis gossypii 252, 254–255 Aphis hederae 256 Aphis helianthi 252 Aphis middletoni 256 Aphis nasturtii 252 Aphis nerii 256 Aphis pomi 256 Aphis sedi 256 Aphrophora cribrata 398 Aphrophora parallella 398 Aphrophora permutata 398 Aphrophora saratogensis 398 Apiomerus spp. 630 Apis mellifera 672 Aporrectodea chlorotica 538 Aporrectodea rosea 538 Aporrectodea trapezoides 538 Aporrectodea tuberculata 538 Aporrectodea turgida 538 apple and thorn skeletonizer 110 apple aphid 256 apple bark borer 426 apple blotch leafminer 230 apple bucculatrix 112 apple curculio 570 apple flea beetle 190 apple flea weevil 200, 218 apple grain aphid 253 apple leafgall midge 236 apple leafhopper 284 apple maggot 576 apple mealybug 372 apple pandemis 134 apple rust mite 320, 606 apple sucker psyllid 278 apple twig borer 352 appleleaf blister mite 332 appleleaf trumpet leafminer 229 Apterona helix 116 arabesque orbweaver 642

Araneus cavaticus 640 Araneus diadematus 642 Araneus gemma 640 Araneus gemmoides 640 Araneus marmoreus 642 Araneus thaddeus 642 Araneus trifolium 642 arboreal orbweaver 642 arborvitae leafminers 232 arborvitae sawfly 156 arborvitae spider mite 314 arborvitae weevil 474 Archips argyrospila 128 Archips cerasivorana 144 Archips fervida 128, 144 Archips goyerana 130 Archips negundana 128 Archips rosana 128 Archips semiferana 128 Arcitalitrus sylvaticus 532 Ardis brunniventris 346 Arge pectoralis 164 Argentine ant 522 Argiope argentata 640 Argiope aurantia 640 Argiope florida 640 Argiope trifasciata 640 argus tortoise beetle 181 Argyotaenia citrana 132, 554 Argyotaenia pinatubana 132 Argyotaenia velutinana 132, 554 Argyresthia cupressella 232, 336 Arhyssus crassus 600 Arhyssus lateralis 600 arid-land subterranean termite 516 Arilus cristatus 630 Arion ater 210 Arion circumscriptus 210 Arion fasciatus 210 Arion rufus 210 Armadillium vulgare 530 armored scales 270–275 army cutworm 494 armyworm 98 armyworms 94–101, 494 arrowhead orbweaver 642 artichoke plume moth 556 Ascia monuste 56 ash and privet borer 446 ash bark beetles 460 ash bulletgall midge 236 ash flowergall mite 606 ash midribgall midge ash whitefly 244 ashgray blister beetle 206 ash-gray leaf bugs 600

ash-lilac borer 344, 424 Asian chestnut gall wasp 416 Asian citrus psyllid 280 Asian cockroach 54 Asian cycad scale 272 Asian giant hornet 588 Asian longhorned beetle 444 Asian tramp snail 212 Asian woolly hackberry aphid 257, 258 Asiatic garden beetle 470, 560 Asiatic oak weevil 198 asparagus aphid 256 asparagus beetle 172 asparagus leafminer 224 aspen carpenterorm 428 aspen leafminer 216 Aspidiotus cryptomeriae 272 Aspidiotus nerii 272 assassin bugs 630 aster leafhopper 288 aster yellows 288 Asterocampa celtis 66 Asterocampa clyton 66 Asterolecanium arabidis 394 Asterolecanium bambusae 394 Asterolecanium minus 394 Asterolecanium pustulans 394 Asterolecanium puteanum 394 Asterolecanium quercicola 394 Asterolecanium variolosum 394 Athrips rancidella 144 Atomocerca decepta 164 Atrusca trimaculosa 234 Atta texana 168 Atteva punctella 144 Aulacaspis yasumatsui 274 Aulacorthum circumflexum 257 Aulacorthum solani 256 Australian cockroach 54 Australian sod fly 506 Autographa californica 102 Autographa precationis 102 Automeris io 82 azalea bark scale 376 azalea caterpillar 74 azalea lace bug 302 azalea leafminer 228 azalea sawflies 158 azalea stem borer 354 azalea whitefly 244 baccharis gall fly 238 baccharis gall mite 332 Bacillus thuringiensis 668 bacterial diseases of insects 668 bacterial leaf scorch 290 Bactericera antennata 280

689

Bactericera cockerelli 276 bagrada bug 300 Bagrada hilaris 300 bagworm 114–115 bagworms 114–117 balaustium mites 650 baldcypress leafroller 130 baldcypress rust mite 320 baldcypress webworm 130 baldfaced hornet 588, 656 Baliosus nervosus 220 balsam needlegall midge 238 balsam twig aphid 368 balsam woolly adelgid 370 bamboo scale 394 banded ash borer 444 banded ash clearwing 426 banded cucumber beetle 176 banded elm bark beetle 454 banded garden spider 640 banded greenhouse thrips 306 banded sunflower moth 554 banded tussock moth 88 banded woollybear 92 bandedwinged whitefly 244 Banks grass mite 314 barberry looper 106 barberry webworm 144 bark beetles 350, 452–463 bark crab spiders 636 barn funnel weaver 646 barn orbweaver 640 barnacle scale 384 Barypeithes pellucidus 198 basswood lace bug 302 basswood leafminer 220 Batrocera dorsalis 578 Batyle ignicollis 568 Batyle suturalis 568 Bdellia somnulentella 228 bdellid mites 650 bean aphid 252 bean leaf beetle 178 bean seed maggot 500 bean thrips 306 Beauveria bassiana 670 bee assassins 630 bee flies 628 beech bark disease 376 beech blight aphid 252, 368 beech scale 376 bees 672–681 beet armyworm 96 beet curly top disease 288 beet leafhopper 288 beet leafminer 222 beet webworm 126 Bemisia tabaci 242–244

INDEX Bermudagrass mite 333 Bermudagrass scale 392 bertha armyworm 98 Bibio spp. 506 big poplar sphinx 72 big-eyed bugs 632 billbugs 478 bindweed mite 332 Bipalium kewense 540 birch catkin bug 600 birch lace bug 302 birch leafminer 226 birch sawfly 164 birch skeletonizer 112 bird cherry-oat aphid 253 black arion 210 black blister beetle 206, 566 black carpenter ant 522 black cherry aphid 252 black cherry fruit fly 576 black citrus aphid 257 black cutworm 492 black field slug 210 black hunter thrips 628 black imported fire ant 520 black margined aphid 256 black pecan aphid 256 black pineleaf scale 268 black polished spruce aphid 256 black scale 384 black soldier fly 510 black stem borer 460 black swallowtail 58 black turpentine beetle 458 black twig borer 462 black vine weevil 196, 472 black walnut curculio 574 black walnut petiolegall mite 333 black widow 644 black-and-yellow garden spider 640 black-and-yellow mud dauber 658 blackheaded ash sawfly 160 blackheaded fireworm 132, 554 blackheaded sawfly 156 blackhorned juniper borer 446 blackhorned pine borer 446 blackhorned tree cricket 48 Blaesodiplosis crataegifolia 238 Blaniulus guttulatus 532 Blastopsylla occidentalis 280 Blatella asahinai 54 Blatta orientalis 54 Blattella germanica 54 blazingstar borer moth 360 Blepharida rhois 192

Blepharidopterus chlorionis 296 Blissus insularis 298 Blissus leucopterus hirtus 298 Blissus leucopterus leucopterus 298 Blissus occiduus 298 blister beetles 206–207, 566, 618 blister coneworm 552 blue orchard mason bee 676 blueberry bud mite 320, 333, 606 blueberry casebearer 182 blueberry gall midge 584 blueberry leafroller 134 blueberry maggot 578 bluegrass billbug 478 bluegrass webworm 124 blue-green citrus weevils 474 blue-green leafhopper 290 bluegum psyllid 280 Boisduval scale 274 Boisea rubrolineata 598 Boisea trivittata 598 bold jumper 638 bollworm 548 bombardier beetles 614 Bondar’s nesting whitefly 246 bougainvillea looper 108 Bourltiella hortensis 534 bowlegged fir aphid 256 boxelder bug 598 boxelder erineum mite 332 boxelder leafminer 228 boxelder leafroller 128 boxelder psyllid 278 boxelder twig borer 342 boxwood leafminer 224 boxwood psyllid 278 boxwood spider mite 314 Brachycaudatus cardui 252 Brachycaudatus helichrysi 252 Brachycorynella asparagi 256 Brachyiulus spp. 532 Brachystola magna 44 braconid wasps 662 Bradybaena similaris 212 Bradysia spp. 508 brassica whitefly 246 Brevicoryne brassicae 254–256 Brevipalpus obovatus 319 Brevipalpus incidii 319 Brevipalpus phoenicis 319 bristly rose sawfly 160 broad mite 318 broadnecked root borer 498 broadwinged katydid 48, 410 Brochymena affinis 595 Brochymena quadripustulata 595

Brochymena sulcata 595 bronze birch borer 432 bronze cane borer 348 bronze poplar borer 436 bronzed cutworm 494 Brooksetta althaeae 296 brown citrus aphid 257 brown garden snail 212 brown lacewings 622 brown marmorated stink bug 594 brown mite 314, 316 brown recluse spider 648 brown soft scale 266, 384 brown spiders 648 brown stink bug 596 brown wheat mite 316 brown widow 644 brownbanded arion 210 brownbanded cockroach 54 brownheaded ash sawfly 160 Bruce spanworm 108 brushfooted butterflies 62 Bryobia praetiosa 316 Bryobia rubrioculus 314, 316 Bucculatrix ainsliella 110 Bucculatrix albertiella 110 Bucculatrix canadensisella 112 Bucculatrix pomifoliella 112 Bucculatrix thurnberiella 112 buckthorn aphid 252 buffalo treehopper 402 buffalograss mealybug 264 buffalograss mite 333 bulb mites 536 bull pine sawfly 156 bumble bee clearwing moths 72 bumble bees 674 bumble flower beetle 470, 560 bumelia borer 498 burrowing sod webworms 496 Bursaphelenchus xylophilus 446 bush katydids 48 butternut woollyworm 162 Byturus bakeri 564 Byturus rubi 564 Byturus unicolor 564 cabbage aphid 254–256 cabbage looper 102 cabbage maggot 500 cabbage webworm 126 cabbage white butterfly 56 Cacoeimorpha pronubana 136 Cacopsylla buxi 278 Cacopsylla negundinis 278 Cacopsylla pyricola 278 Cacopsylla tobirae 278

690

Cacopsylla triozimima 278 Cactoblastis cactorum 430 cactus longhorn 446 cactus scale 274 Caenugina crassiuscula 104 Caenurgina erechta 104 Calameuta clavata 360 Calastega aceriella 112 calico scale 380 California mantid 634 California oakworm 76 California orangedog 60 California pear sawfly 160 California prionus 498 California red scale 392, 604 Caliothrips fasciatus 306 Caliroa cerasi 166 Caliroa fasciata 166 Caliroa lobata 166 Caliroa petiolata 166 Caliroa quercuscoccineae 166 Callaphis betulaecolens 256 Callaphis juglandis 256 Calligrapha californica coreopsivora 188 Calligrapha philadelphica 188 Calligrapha scalaris 188 Callipterinella callipterus 256 Callirhopalus bifasciatus 198 Callirhytis cornigera 414 Callirhytis fructuosa 588 Callirhytis gemmaria 414 Callirhytis operator 588 Callirhytis quercusgemmaria 414 Callirhytis quercuspunctata 414 Callirhytis seminator 414 Callopistria floridensis 100 Callosomia angulifera 80 Callosomia promethean 80 Calopha graminis 252 Calopha ulmicola 252 Calophya rubra 328 Caloptilia azaleella 228 Caloptilia negundella 228 Caloptilia syringella 228 Calpodes ethlius 138 cambium miners 356 camel crickets 48 camellia bud mite 606 camellia scale 274 Cameraria caryaefoliella 228 Cameraria spp. 228 camerobiid mites 650 Camnula pellucida 44 Camponotus floridanus 522 Camponotus herculeanus 522

INDEX Camponotus novaboracensis 522 Camponotus pennsylvanicus 522 campylomma bug 592 Campylomma verbasci 592 Canada thistle gall fly 418 candy-striped leafhopper 290 cankerworms 104–107 cannabis aphid 257 Capitophorous eleagni 252 caragana blister beetle 206 carder bees 676 Carmenta anthracipennis 360 Carmenta corni 490 carnation tortrix 136 Carneocephala fulgida 290 Carolina grasshopper 44 Carolina mantid 634 Carolina sphinx 68 Carolina wolf spider 638 carpenter ants 522–525, 654 carpenter bees 364, 674–676 carpenterworm 428 Carpophilus lugubris 562 carrot beetle 470 carrot root aphid 252 carrot rust fly 504 carrot weevil 476 Carulaspis juniperi 272 Caryomyia spp. 238 casebearers 118 case-bearing leaf beetles 182–183 Cassida rubiginosa 182 catalpa midge 238 catalpa sphinx 70 caterpillar hunters 614 catfaced spider 640 Catocala spp. 100 Caulocampus acericaulis 346 ceanothus stem gall moth 420 Cecidomyia piniinopis 342 Cecidomyia resinicola 342 Cecidophyopsis psilaspis 333 Cecidophyopsis ribis 333 Ceciophyes betulae 333 cecropia moth 78 cedar bark beetles 340 celery leaftier 126 celery looper 102 cellar spiders 648 centipedes 27, 652 Cephalcia spp. 152 Cephus cinctus 360 Cephus pygmaeus 360 Ceratagallia abrupta 288 Ceratagallia singuinolenta 290

Ceratina spp. 364, 676 Ceratitis capitata 578 Ceratoma trifucata 178 Ceratomia amyntor 70 Ceratomia catalpae 70 Ceratomia undulosa 70 cereal leaf beetle 172 Ceroplastes ceriferus 268, 384 Ceroplastes cirripediformis 384 Ceroplastes floridensis 268, 384 Ceroplastes rubens 384 Ceroplastes sinensis 384 Ceruaphis eriophori 252 Ceruaphis viburnicola 252 Ceuthophilus spp. 48 Chaetocnema confinis 194 Chaetocnema denticulata 194 Chaetocnema pulicaria 194 Chaetocnema repens 194 Chaetopsis massyla 584 Chaetosiphon fragaefolii 257 Chaitophorus nudus 366 Chaitophorus populicola 256, 366 Chaitophorus populifolii 256 Chaitophorus viminalis 256 chalcid wasps 664 Chalcodermus aeneus 572 Charidotella sexpunctata 180 Chauliognathus basalis 566 Chauliognathus marginatus 566 Chauliognathus pensylvanica 566, 616 Chauliognathus scutellaris 566 checkered beetles 620 checkered melon beetle 176, 564 checkered white butterfly 56 cheese mite 536 Cheiracanthium inclusum 646 Cheiracanthium mildei 646 Chelinidea vittiger 292 Chelymorpha cassidea 181 Chelymorpha cribraria 181 cherry bark tortrix 132 cherry curculio 570 cherry fruit fly 576 cherry fruit sawfly 558 cherry fruitworm 344, 544 cherry lace bug 302 cherry maggot 576 cherry slug 166 chiggers 650 chilli thrips 308 Chilochorus stigmata 610 chimney crayfish 530 China mark moth 120 chinch bugs 298 Chinese mantid 634

Chinese red scale 384 Chionaspis americana 390 Chionaspis furfura 390 Chionaspis pinifoliae 270 Chionaspsis heterophyllae 270 Chlorochroa ligata 596 Chlorochroa sayi 596 Chlorochroa uhleri 596 Chlosyne gorgone 66 chocolate arion 210 chokecherry fruitgall midge 584 chokecherry sawfly 160 Choreutis pariana 110 Choristoneura conflictana 130 Choristoneura rosaceana 130, 554 Chromaphis juglandicola 256 chrysanthemum aphid 256 chrysanthemum gall midge 238 chrysanthemum lace bug 302 chrysanthemum leafminer 214 chrysanthemum rust mite 321 Chrysobothris femorata 438 Chrysobothris mali 438 Chrysochus auratus 178 Chrysomela knabi 188 Chrysomela scripta 186 Chrysomphalus aonidum 272 Chrysopa spp. 620 Chrysoperla spp. 620 Chrysoteuchia topiaria 496 cicada killers 658 cicadas 406–409 cigar casebearer 118 Cimbex americana 164 Cinara coloradensis 256 Cinara curvipes 256 Cinara fornacula 256 Cinara laricis 256 Cinara sabiniae 256 Cinara spp. 366 Cinara strobi 256 Circulifer tenellus 288 Citheronia regalis 78 citricola scale 266 citronella ants 522 citrophilus mealybug 262 citrus blackfly 246 citrus bud mite 333 citrus flatid planthopper 400 citrus greening disease 280 citrus leafminer 216 citrus mealybug 260, 604 citrus peelminer 556 citrus red mite 314 citrus rust mite 321, 606 citrus whitefly 246 Cladius difformis 160

691

Clastoptera achatina 398 Clastoptera delicata 398 Clastoptera doeringae 398 Clastoptera obtusa 398 Clastoptera proteus 398 clavate tortoise beetle 182 clay-colored weevil 196, 472 clearwing borers 344, 424–427 clearwing sphinx 72 clearwinged grasshopper 44 clematis blister beetle 206 clerid beetles 620 click beetles 480 Clinodiplosis rhododendri 238 Clostera inclusa 150 clouded sulfur 56 clover leaf weevil 200 clover leafhopper 290 clover looper 104 clover mite 316 cluster flies 540 Cnephasia longa 136 cobweb weaver spiders 644 Coccinella septempunctata 610 Coccotorus scutellaris 570 Coccus herperidum 266, 384 Coccus pseudomagnoliarum 266 Coccus viridis 266 cochineal 264 Cochylis hospes 554 cockroaches 54–55 cocktail ants 524 coconut mealybug 262 codling moth 542 Coleomegilla maculata 610 Coleophora laricella 118 Coleophora laticornella 118 Coleophora malivorella 118 Coleophora serratella 118 Coleophora ulmifoliella 118 Coleotechnites apicitripunctella 130 Coleotechnites picealla 232 Coleotechnites ponderosae 232 Colias eurytheme 56 Colias philodice 56 Colladonus montanus 288 Collops spp. 566, 618 Colomerus vitis 333 Colopha ulmicola 322 Coloradia pandora 82 Colorado potato beetle 170 Colorado soldier beetle 566 columbine borer 358 columbine leafminer 216 columbine sawfly 160 common (northern) walkingstick 50

INDEX common birch aphid 256 common buckeye 66 common chinch bug 298 common crane fly 506 common falsepit scale 394 common flower scarab 560 common pine shoot beetle 340 common short-tailed cricket 514 common willow agrilus 436 Comstock mealybug 262 conchuela 596 concrete mites 650 coneflower borer 358 coneworms 552 Conoderus spp. 480 Conophthorus ponderosae 574 Conotrachelus aratus 350 Conotrachelus hicoriae 574 Conotrachelus nenuphar 568 Conotrachelus retentus 572 Conotrachelus schoofi 350 consperse stink bug 596 Contarinia canadensis 238 Contarinia catalpae 238 Contarinia citrina 420 Contarinia coloradensis 238 Contarinia juniperina 342 Contarinia nasturtii 364 Contarinia pseudotsugae 238 Contarinia quinquenotata 584 Contarinia schulzi 584 Contarinia verrucicola 238 Contarinia virginianae 584 Continaria negundinis 236, 238 convergent lady beetle 610 convict caterpillar 490 Cooley spruce gall adelgid 422 Coptodisca arbutiella 229 Coptodisca splendoriferella 229 Coptotermes formosanus 516 Coptotriche malifoliella 229 coreopsis beetle 188 corn blotch leafminer 222 corn earworm 548 corn flea beetle 194 corn leaf aphid 257 corn root aphid 522, 526 corn root webworm 124 cornsilk flies 584 Cornu aspersum 212 Coryphista meadii 106 Corythuca angulata 302 Corythuca arcuata 302 Corythuca celtidis 302 Corythuca ciliata 302 Corythuca cydoniae 302 Corythuca distincta 302 Corythuca juglandis 302

Corythuca marmorata 302 Corythuca pallipes 302 Corythuca pruni 302 Corythuca ulmi 302 Cosetacus camelliae 606 Cosmopepla lintneriana 596 Cossula magnifica 428 Cotinus mutabilis 468,560 Cotinus nitidis 468, 560 cotoneaster webworm 144 cotton square borer 556 cotton/melon aphid 252, 254–255 cottonwood borer 498 cottonwood catkingall mite 606 cottonwood clearwing borer 426 cottonwood crown borer 488 cottonwood dagger moth 88 cottonwood leaf beetle 186 cottonwood leafcurl mite 332 cottonwood twig borer 342 cottony ash psyllid 280, 328 cottony camellia scale 266, 382 cottony cushion scale 386 cottony maple leaf scale 266 cottony maple scale 382, 382 cottony taxus scale 266, 382 cowpea aphid 257 cowpea curculio 572 Crambus leachellus 124 Crambus praefectellus 124 Crambus sperryellus 124 cranberry fruitworm 552 cranberry girdler 496 cranberry leafroller 134 cranberry rootworm 178 crane flies 504–507 crapemyrtle aphid 257 crapemyrtle scale 376 Craponius inaequalis 572 crayfish 530 Crematogaster spp. 524 crescent-marked lily aphid 257 cribate root weevil 196 crickets 46–48, 514 Criddle’s bark beetle 456 Crioceris asparagi 172 Crioceris duodecimpunctata 172, 564 Croesus litatarsus 160 cross orbweaver 642 Crossidius spp. 568 cross-striped cabbageworm 126 croton scale 268 crucifer flea beetle 192 Cryptococcus fagisuga 376 Cryptolaemus montrouzieri 612 cryptomeria scale 272

Cryptomyzus ribis 252 Cryptoneossa triangula 280 Cryptorhyncus latapthe 448 Ctenarytaina eucalptyi 280 Ctenicerca spp. 480 Cuban brown snail 212 Cuban laurel thrips 308 cucurbit yellow vine disease 292 Curculio caryae 574 Curculio caryatrypes 574 Curculio obtusus 574 Curculio occidentis 574 Curculio sayi 574 curled rose sawfly 160, 346 currant aphid 252 currant borer 344 currant bud mite 333 currant fruit fly 578 currant sawfly 158 currant spanworm 108 cutworms 94–97, 492–497, 548–551 cybocephalid beetles 620 Cybocephalus nipponicus 620 cycad aucalaspis scale 274 cyclamen mite 318 Cyclocephala borealis 464 Cyclocephala hirta 466 Cyclocephala longula 466 Cyclocephala lurida 466 Cyclocephala pasadenae 466 Cydia caryanae 542 Cydia latiferreana 544 Cydia nigrescens 544 Cydia pomonella 542 Cylas formicarius 476 Cylindrocopturus adspersus 362 Cylindroiulus spp. 532 cypress bark mealybug 372 cypress flower gall midge 584 cypress tipminer 232, 336 cypress twiggall midge 238, 418 Cyrtepistomus castaneus 198 Dactylopius coccus 264 Dactylopius confusus 264 Dactylopius opuntiae 264 daddy longlegs 648 dagger moths 88 Dahlica lichenella 116 Dahlica triquetrella 116 Daktulosphaira vitifoliae 324, 528 Dalotia coriaria 616 damsel bugs 630 damselflies 26, 636 Danaus gilippus 64 Danaus plexippus 64

692

dance flies 626 Darapsa myron 70 darksided cutworm 494 Dasineura communis 236 Dasineura gledischiae 236 Dasineura mali 236 Dasineura oxycoccana 584 Dasineura pellex 236 Dasineura piceae 342 Dasineura pyri 236 Dasineura rhobdophaga 356, 582 Datana integerrina 74 Datana major 74 Datana ministra 74 daylily leafminer 216 daylily thrips 304 decollate snail 212, 652 decorated strawberry root weevil 196 dectes stem borer 362 Dectes texana 362 Delia antiqua 500 Delia florigela 500 Delia panipalpis 500 Delia platura 500 Delia radicum 500 Deloyala guttata 181 Deltocephala hospes 290 Dendroctonus frontalis 456 Dendroctonus ponderosae 458 Dendroctonus rufipennis 458 Dendroctonus tenebrans 458 Dendroctonus valens 458 Dendrodrilus rubidus 540 Dendrothrips ornatus 306 deodar weevil 338 Deraeocoris spp. 630 Deroceras laeve 208 Deroceras reticulatum 208 Desmia funeralis 136 Desmocerus palliatus 498 destructive prune worm 552 devastating grasshopper 42 devil crayfish 531 Diabrotica balteata 176, 484 Diabrotica barberi 176, 482 Diabrotica undecimpunctata 174, 484, 564 Diabrotica virgifera virgifera 176, 482, 564 Diabrotica virgifera zeae 482 Dialeurodes chittendeni 244 Dialeurodes citri 246 diamondback moth 110 Diaphania hyalinata 550 Diaphania nitidalis 550 Diapheromera femorata 50

INDEX Diapheromera velii 50 Diaphorina citri 280 Diaprepes abbreviatus 474 diaprepes root weevil 474 Diaspidiotus gigas 392 Diaspidiotus liquidambaris 272 Diaspis boisduvalii 274 Diaspis echinocacti 274 Dichomeris marginella 142 dichondra flea beetle 194 Diestrammena asynamora 48 differential grasshopper 42 digger bees 678 digger crayfish 530 Dimorphopteryx melanognathus 160 dingy cutworm 494 Dioryctria abietivorella 552 Dioryctria albovittella 336 Dioryctria amatella 336, 430, 552 Dioryctria auranticella 543 Dioryctria cambiicola 336, 430 Dioryctria clarioralis 552 Dioryctria disclusa 543 Dioryctria ponderosae 336, 430 Dioryctria renicullelloides 552 Dioryctria resinosella 336 Dioryctria zimmermani 430 Diplolepis bicolor 234 Diplolepis dichlocera 416 Diplolepis fusiformis 416 Diplolepis nebulosus 234 Diplolepis radicum 416 Diplolepis rosae 416 Diplolepis rosaefolii 234 Diplolepis spinosa 416 Diplolepis tumidus 416 Diploptera punctata 54 Diprion similis 156 Disclisioprocta stellata 108 Dishocaspis quercusvirens 412 Disholcaspis coloradensis 412 Disholcaspis eldoradensis 412 Disholcaspis mamillaria 412 Disholcaspis quercusmamma 412 Disholcaspis simulata 412 Disonycha mellicollis 190 Disonycha triangularis 190 Disonycha xanthomelas 190 Dissosteira carolina 44 distinct lace bug 302 dogbane beetle 178 dog-day cicadas 408 dogwood borer 426 dogwood clubgall midge 420 dogwood sawflies 162

dogwood spittlebug 398 dogwood twig borer 354 Dolichovespula arenaria 588, 656 Dolichovespula maculata 588, 656 Dolomedes tenebrosus 638 Dolomedes triton 638 Donacia piscatrix 188 Dorchaschema alternatum 354 Doru spp. 636 Douglas-fir needlegall midge 238 Douglas-fir tussock moth 86 Draeculacephala minerva 290 dragonflies 26, 636 Drepanosiphum platanoides 256 drippy blight disease 394 drone flies 624 Drosophila spp. 510, 582–583 Drosophila suzukii 580 dryberry mite 606 Dryocampa rubicunda 82 Dryocosumus kuriphilus 416, 588 dung flies 510 dusky birch sawfly 160 dusky sap beetle 562 dusky slug 210 dusky-winged oak aphid 256 dusky-winged poplar aphid 366 dusky-winged walnut aphid 256 dustywings 622 Dysaphis planaginea 252 Dysaphis tulipae 257, 526 Dysdera crocata 640 dysderid spiders 640 Dyslobus decoratus 196 Dyslobus granicollis 196 Dysmicoccus wistariae 372 Eacles imperialis 80 earthworms 538–541 earwigs 52–53, 636 eastern ash bark beetle 456 eastern buck moth 82 eastern carpenter bee 674 eastern grape leafhopper 286 eastern lubber grasshopper 44 eastern pine looper 108 eastern pine shoot borer 336 eastern pine weevil 338 eastern raspberry fruitworm 564 eastern spruce gall adelgid 422 eastern tent caterpillar 148 eastern tiger swallowtail 60 eastern yellowjacket 586, 656 Ecdytolopha insiticiana 344

Edwardsiana australis 286 Edwardsiana commisuralis 286 Edwardsiana hippocastani 286 Edwardsiana rosae 284 eggplant flea beetle 194 eggplant lace bug 302 eggplant tortoise beetle 182 Ehrhornia cupressi 372 eightspotted forester 100 Eisenia foetida 540 elder shoot borer 344 elderberry borer 498 elegant sod webworm 124 elm agromyzid leafminer 224 elm borer 442 elm calligrapha 188 elm casebearer 118 elm cockscomb aphid 252, 322 elm eriophyid mite 332 elm lace bug 302 elm phloem necrosis disease 290 elm sawfly 164 elm scurfy scale 390 elm spanworm 106 elm sphinx 70 elm spider mite 314 elm-grass root aphid 322 elongate flea beetle 194 elongate hemlock scale 272 Elophila obliteralis 120 emerald ash borer 434 Emesaya spp. 630 Emmelina monodactyla 556 Empoasca abrupta 284 Empoasca fabae 282 Empoasca filament 284 Empoasca maligna 284 Empoasca recurvata 284 Empoasca solana 284 Empyreuma affinis 88 Enarmonia formosana 132 Enchenopa binotata 402 encyrtid wasps 664 Endelomyia aethiops 166 Endria inimica 290 engravers 458 Engytatus modestus 592 Ennomos subsignaria 106 entomopathogenic nematodes 670 Entomophthora grylli 668 Entomophthora maimaiga 668 Entomophthora muscae 668 Entomoscelis americana 176 Entylia carinata 404 Eotetranychus hicoriae 314 Eotetranychus lewisi 314 Eotetranychus matthyssei 314

693

Eotetranychus populi 314 Eotetranychus querci 314 Eotetranychus tiliarium 314 Eotetranychus weldoni 314 Epargyreus clarus 138 Epicauta cinerea 206 Epicauta fabricii 206 Epicauta ferruginea 206 Epicauta funebris 206 Epicauta maculata 206 Epicauta pennysylvanica 206, 566 Epicauta subglabra 206 Epicauta vittata 206 Epilachna borealis 204 Epilachna varivestis 204 Epinotia nisella 344 Epinotia solicitana 344 Epiphyas postvittana 132, 554 Episimus argutanus 136 Episimus tyrius 342 Epitrimerus pyri 320, 606 Epitrimerus taxodii 320 Epitrix cucumeris 194, 484 Epitrix fuscula 194 Epitrix hirtipennis 194 Epitrix subcrinata 194, 484 Epitrix tuberis 194, 484 Erannis tiliaria 106 Eratigena agrestis 646 erigeron root aphid 526 Eriocampa juglandis 162 Eriococcus araucariae 376 Eriococcus azalae 376 Eriococcus gillettei 376 Eriococcus lagerostroemia 376 Eriococcus quercus 376 Eriophyes calceris 333 Eriophyes celtis 333 Eriophyes cerasicrumena 332 Eriophyes cynodoniensis 333 Eriophyes emarginatae 332 Eriophyes mali 332 Eriophyes pyri 332 Eriophyes sheldoni 333, 606 Eriophyes slykhuisi 333 Eriophyes sorbi 332 Eriophyes tiliae 332 Eriophyes tosichella 320, 332 Eriophyes ulmi 332 Eriophyes zoysiae 333 eriophyid mites 320–321, 328–333, 606 Eriosoma americanum 252, 258, 368, 526 Eriosoma crataegi 252, 258, 368 Eriosoma lanigerum 252, 258, 526

INDEX Eriosoma pyricola 252, 258, 368 Eriosoma rileyi 258, 368 Erythraspides vitis 160 Erythroneura comes 286 Erythroneura gleditsiae 286 Erythroneura lawsoniana 286 Erythroneura variabilis 286 Erythroneura vulnerata 286 Erythroneura zic-zac 286 Estigmene acrea 92 Etiella zinckenella 552 Euborellia annulipes 52, 636 Eucallipterus tiliae 256 Eucalymnatus tessellatus 268 Eucalyptolomya maidenii 280 eucalyptus longhorned borer 444 Euchaetes egle 86 Euclea delphinii 84 Euclea nanina 84 Eucopina gloriola 336 Eucosoma sonomana 336 Eucosoma tocullionana 543 Eudrilus eugeniae 540 Euetheola humilis 468 eugenia psyllid 328 Euglandina rosae 212, 652 Euhagena nebraskae 490 Eulecanium cerasorum 380 eulophid wasps 664 Eumargarodes laingi 528 Eumenes spp. 656 Eumeris strigatus 502 Eumeris tuberculatus 502 Eumorpha achemon 66 Eumorpha pandorus 66 euonymus leaf notcher 112 euonymus scale 272, 390 Euphantra canadensis 578 Euphoria inda 470, 560 Euphoria kerni 560 Euptoieta claudia 66 Eurasian hemp borer 360, 545 European alder leafminer 226 European corn borer 358, 542 European crane fly 504 European earwig 52, 636 European elm flea weevil 200, 216 European elm scale 374 European fire ant 524 European fruit lecanium 378 European fruit sawfly 558 European grapevine moth 554 European hornet 588 European paper wasp 654 European peach scale 378 European pine sawfly 156 European pine shoot moth 334

European red mite 312 European red slug 210 European shothole borer 462 European skipper 140 European wheat stem sawfly 360 Eurosta solidaginsis 418 Eurybia macrophylla 490 Eurytetranychus admes 314 Eurytetranychus buxi 314 Euschistis variolarius 596 Euschistus conspersus 596 Euschistus servus 596 Euthochtha galeator 604 Euthyrhynchus floridanus 628 Euura spp. 416 Euwallacea spp. 462 Euxesta eluta 584 Euxesta stigmatias 584 Euxoa auxiliaris 494 Euxoa messoria 494 Euxoa ochrogaster 494 Euzophera semifuneralis 430 Evergestis pallidata 126 Evergestis rimosalis 126 Exitianus exitiosus 290 Exomala orientalis 468 eyespot gall midge 238 eyespotted bud moth 130, 554 eyespotted lady beetle 610 fairyflies 664 fall armyworm 94–96 fall cankerworm 104 fall field cricket 46 fall webworm 146 Fallicrambus fodiens 530 false celery leaftier 126 false chinch bugs 299, 600 false Japanese beetle 470, 558 false potato beetle 170 false spider mites 318 false unicorn caterpillar 76 falsepit scales 394 Fannia canicularis 510 Fasciata cercerisella 136 Feltia jaculifera 494 Feltia subgothica 494 Feltiella acarisuga 624 fennel aphid 257 Fenusa dohrnii 226 Fenusa pusilla 226 fern scale 274 Ferrisia gilli 26 Ferrisia virgata 264 ficus whitefly 246 Fieberiella florii 288 field ants 520, 654 fiery skipper 140

fig eater beetle 468, 560 filament bearer 108 filbert aphid 257 filbert bud mite 333 filbert leafroller 128 filbert weevil 574 filbertworm 544 Fiorina externa 272 Fiorina theae 272 fir coneworm 552 fir rust mite 320 fire ants 518–521, 654 fireflies 618 Fissicrambus mutabilis 124 fivespotted sphinx/hawk moth 68 flannel moths 84 flatheaded appletree borer 438 flatheaded borers 348–349, 432–439 flea beetles 190–195 flea weevils 200 flesh flies 666 Fletcher scale 378 Florida fern caterpillar 100 Florida garden spider 640 Florida leatherleaf 210 Florida mantid 634 Florida predatory bug 628 Florida red carpenter ant 522 Florida red scale 272 Florida wax scale 268 flower crab spiders 636 flower flies 624 flower longhorns 568 flower thrips 308, 590 fly parasites 664 folded-leaf poplar aphid forage looper 104 Forda formicaria 257, 526 Forda marginata 526 forest nursery spider 638 forest tent caterpillar 150 Forficula auricularia 52 Formica spp. 520 Formosan subterranean termite 516 fourlined fruitworm 560 fourlined plant bug 294 fourspotted hawthorn aphid 257 fourspotted sap beetle 562 fourspotted spider mite 312 foxglove aphid 256 Frankliniella fusca 308, 590 Frankliniella occidentalis 308, 590 Frankliniella tritici 308, 590 Franklinothrips vespiformis 628

694

fringed birch sawfly 160 frosted scale 378 fruit flies 510, 576–582 fruittree leafroller 128 fruit-tree pinhole borer 462 fuchsia gall mite 332 Fuller rose beetle 198 fungal diseases of insects 668 fungus gnats 508 funnel weavers 646 furrow spider 640 Galendromus occidentalis 650 gall midges 236–239, 418–419 gall wasps 234–235, 410–417 galls 234–239, 322–333 Gambel oak borer 436 garden fleahopper 294 garden springtail 534 garden symphylan 536 garden webworm 126 Gargaphia solani 302 Gargaphia tilia 302 garlic glass snail 212 Gasteracantha cranciformis 642 Geina persicelidactylus 556 genista caterpillar 136 Geocoris pallens 632 Geocoris punctipes 632 Geocoris uliginosus 632 Georgia jumper 540 geranium plume moth 556 German cockroach 54 German yellowjacket 586, 656 Geshna cannalis 136 ghost ants 654 giant bark aphid 257, 366 giant conifer aphids 366 giant garden slug 210 giant ichneumon wasp 662 giant root borers 498 giant silkworms 78–83 giant swallowtail 60 giant whitefly 246 giant willow aphid 257, 366 Gill’s mealybug 264 gladiolus thrips 306, 590 glass snails 212 glassy cutworm 496 glassy-winged leafhopper 290 Glischrochilus fasciatus 562 Glischrochilus quadrisignatus 562 globose springtails 534 gloomy scale 392 Glycaspis brimblecomei 280 Gnorimoschema gallaesolidaginis 418

INDEX golden mealybug 262 golden oak scale 394 golden silk spider 640 golden tortoise beetle 180 goldenglow aphid 257 goldenrain tree bug 600 goldenrod leafminer 220 goldenrod soldier beetle 566 goldspotted oak borer 436 Gossyparia spuria 374 gouty oak gall 414 gouty veingall midge 236 Graminella sonora 290 granulate ambrosia borer 460 granulate poplar borer 436 granulosis viruses 668 grape berry moth 554 grape cane gallmaker 352 grape cane girlder 352 grape curculio 572 grape erineum mite 332, 333 grape flea beetle 190 grape leaffolder 136 grape mealybug 372, 604 grape phylloxera 324, 528 grape plume moth 556 grape root borer 490 grape sawfly 160 grape tube gall maker 238 grape tumid gallmaker 238 grapeleaf skeletonizer 112 Graphocephala coccinea 290 Grapholita delineana 360 Grapholita molesta 344. 544 Grapholita packardi 344, 544 Grapholita prunivora 545 grass bagworm 116 grass sawfly 162 grass seed sawfly 162 grass thrips 306 grass tubeworm moths 496 grass-carrying wasps 658 grasshoppers 42–45 Gratiana pallidula 182 gray garden slug 208 gray hairstreak 556 gray lawn leafhopper 290 gray sunflower seed weevil 572 great ash sphinx 70 great golden digger wasp 658 great southern white 56 greater angle-wing katydid 48 greedy scale 392 green banana cockroach 54 green fruitworm 560 green immigrant weevil 196 green June beetle 464, 468, 560 green lacewings 620

green lynx spider 644 green muscardine disease 670 green peach aphid 248–252 green scale 266 green sharpshooter 290 green spruce aphid 256 green stink bug 596 green sweat bees 680 greenbug 257 greenhouse camel cricket 48 greenhouse leaftier 126 greenhouse millipede 532 greenhouse slug 210 greenhouse thrips 306 greenhouse whitefly 242 greenstriped mapleworm 82 ground beetles 614 ground mealybug 528 ground pearls 528 Grylloprociphilus imbricator 252, 258, 368 Gryllus pennsylvanicus 46 Gryllus rubens 46 Gryllus texensis 46 Gryllus veletis 46 Gynaikothrips ficorum 308 Gynaikothrips uzeli 308 Gypsonoma haimbachiana 342 gypsy moth 90 Gyropsylla ilicis 328 hackberry blistergall psyllid 326 hackberry budgall psyllid 326 hackberry butterfly 66 hackberry lace bug 302 hackberry leaf slug 84 hackberry nipplegall maker 326 hackberry petiolegall psyllid 326 hackberry stargall psyllid 326 hackberry witches’-broom mite 333 hag moth 84 hairy chinch bug 298 hairy spider weevil 198 Halticotoma valida 296 Halticus bractatus 294 Halyomorpha halys 594 Halysidota tessellaris 88 Hammelistes spinosus 252, 322 hammerhead worms 540 Haplorhynchites aeneus 572 harlequin bug 300 Harmonia axyridis 610 Harrisina americana 112 Harrisina metallica 112 Hartigia cressoni 346 Hartigia trimaculata 346 harvester ants 524

harvestmen 648 hawthorn lace bug 302 hawthorn leafminer 226 hawthorn mealybug 372 hazelnut weevil 574 hedgehog gall wasp 234 Helicoverpa zea 548 Heliothis phloxiphaga 546 Heliothis subflexa 546 Heliothis virescens 546 Heliothrips haemorrhoidalis 306 Hellinsia kellicottii 360 Hellula rogatalis 126 Hemeris diffinis 72 Hemeris thysbe 72 hemerocallis gall midge 584 Hemiberlesia lantaniae 392 Hemiberlesia rapax 392 Hemileuca lucina 82 Hemileuca maia 82 Hemileuca nevadensis 82 Hemisphaerota cyanea 182 hemispherical scale 384 hemlock looper 108 hemlock rust mite 321 hemlock sawfly 156 hemlock scale 272 hemlock woolly adelgid 370 hemp russet mite 320, 332 Hercinothrips femoralis 306 Hermetia illucens 510 Herpetogramma phaeopteralis 124 Heterocampa guttivitta 76 Hexomyza schineri 420 hibiscus bug 600 hibiscus sawfly 164 hickory bark beetle 452 hickory gall midges 238 hickory horned devil 78 hickory leafstem gall phylloxera 324 hickory nut curculio 574 hickory shoot curculio 350 hickory shuckworm 542 hickory spiral borer 348 hickory tussock moth 88 Himella intractata 560 Hippodamia convergens 610 Hippodamia parenthesis 610 Hippodamia variegata 610 hobo spider 646 Hogna carolinensis 638 holly bud moth 132 holly leafminer 220 holly looper 106 holly pit scale 394

695

hollyhock leaf skeletonizer 112 hollyhock plant bug 296 hollyhock sawfly 164 hollyhock weevil 574 Hololena spp. 646 Homadaula anisocentra 142 Homaledra sabalella 112 Homalodisca vitripennis 290 Homeolababus analis 200 Homoeosoma electella 552 honey bee 672 honeydew 28, 240 honeylocust borer 436 honeylocust leafhopper 288 honeylocust plant bug 296 honeylocust podgall midge 236 honeylocust rust mite 320 honeylocust spider mite 314 honeysuckle witches’-broom aphid 256 hop aphid 253 hop flea beetle 194 hop vine borer 358 hoplia beetle 470, 560 Hoplia callipyge 470, 560 Hoplia modesta 560 Hoplia oregona 560 Hoplocampa cookei 558 Hoplocampa lacteipennis 558 Hoplocampa testudinea 558 hopperburn 282 Hordnia atropunctata 290 Hormaphis hamamelidis 322 horned oak gall wasp 414 horned spanworm 108 horned squash bug 292 hornet moth 488 hornets 586–588 horntails 356, 450 hornworms 68–73 horsehair worms 670 horseradish flea beetle 192 house centipede 652 house fly 510 hover flies 624 huanglongbing disease 280 hummingbird clearwing 72 hummingbird moths 68, 70, 72 humpbacked flies 510 hunting billbug 478 hunting wasps 654–660 Hyadaphis crategi 252 Hyadaphis foeniculi 257 Hyadaphis tartaricae 256 Hyalophora cecropia 78 Hyalopterus pruni 252 Hydraecia immanis 358 Hydraecia micacea 358

INDEX hydrangea leaftier 136 Hyella azteca 532 Hylephila phyleus 140 Hyles lineata 70 Hylesinus aculeatus 456 Hylesinus californicus 456 Hylesinus criddlei 456 Hylobius pales 338 Hylobius radicis 474 Hylurgopinus rufipes 454 Hypera nigrirostris 200 Hypera postica 200 Hypera zoilus 200 Hyphantria cunea 146 Hysteroneura setariae 252 Icerya purchasi 386 ichneumonid wasps 662 impatiens necrotic spot 590 imperial moth 80 imported cabbageworm 56 imported currantworm 158 imported willow leaf beetle 186 inchworms 104–109 Indian wax scale 268, 384 inkberry leafminer 220 Inopus rubriceps 506 insect diseases 668–671 insect parasitoids 660–669 insect pathogens 668–671 intermountain leafhopper 284 introduced basswood thrips 306 introduced pine sawfly 156 io moth 82 Ips avulus 458 ips beetles 458 Ips calligraphus 458 Ips confusus 458 Ips hunteri 458 Iridothrips iridis 306 iris borer 488 iris thrips 306 irregular pine scale 382 Isabella moth 92 Ischyropalpus spp. 566 Isochnus rufipes 218 Ithycerus noveboracensis 198 ivy aphid 256 Jadera haematoloma 600 Janetiella brevicauda 238 Janus abbreviatus 346 Janus bimaculatus 346 Janus quercusae 346 Janus rufiventris 346 Japanagromyza viridula 224 Japanese beetle 202, 466, 558 Japanese maple scale 390

Japanese mealybug 372 Jerusalem cricket 514 Jonathonota nigripes 181 Josephiella microcarpae 236 jumping oak gall wasps 234 jumping spiders 638 June beetles 202, 466–469 juniper berry mite 606 juniper midge 342 juniper root weevil 198 juniper sawfly 156 juniper scale 272 juniper spittlebug 398 juniper tip dwarf mite 333 juniper twig girdler 336 juniper webworm 142 Junonia coenia 66 Kaliofenusa ulmi 226 katydids 48–49 Keiferia lycopersicella 554 kermes scale 394 Knab’s leaf beetle 188 kudzu bug 300 Kuroshio shothole borer 462 Labidomera clivicollis 178 Labidura riparia 52 lace bugs 302 Lacunicambarus diogenes 531 lady beetles 204, 610–613 ladybugs 610–613 Lambdina fiscellaria 108 Languria mozardi 362 lantana lace bug 302 lantania scale 392 larch aphid 256 larch casebearer 118 larch sawfly 160 large aspen tortrix 130 large carpenter bees 364, 674 large chestnut weevil 574 large milkweed bug 598 large yellow underwing 100 larger canna leafroller 136, 138 larger elm leaf beetle 184 larger sod webworm 122 larger yellow ant 522 Larinioides cornuta 640 Lasius alienus 522 Lasius claviger 522 Lasius interjectus 522 Lasius neoniger 522 Lasius pallitarsus 522 Latrodectus geometricus 644 Latrodectus hesperus 644 Latrodectus mactans 644 Latrodectus variolus 644

lattice orbweaver 642 laurel psyllid 328 lawn leafhopper 290 lawn shrimp 532 Leach’s crambus 124 leaf crumpler 120 leafcurl ash aphid 257, 258 leafcurl plum aphid 252 leafcutter bees 168, 364, 676 leaffooted bug 602 leaffooted bugs 292, 602–605 leaffooted pine seed bug 602 leafhoppers 282–293 leafminers 214–231 leafrollers 128–140 leafrolling weevils 200 Lecanodiaspis prosopidis 394 Lecanopsis formicarum 268 Lehmannia valentiana 210 Leidyula floridana 210 Lema daturaphila 172 Lema trivittata 172 lemongum psyllid 280 leopard moth 428 leopard slug 210 Lepidosaphes beckii 274 Lepidosaphes camelliae 274 Lepidosaphes pallida 274 Lepidosaphes pini 274 Lepidosaphes sciadopitysi 274 Lepidosaphes ulmi 388 Lepidosaphes yanangicola 274 Leptinotarsa decemlineata 170 Leptinotarsa juncta 170 Leptoglossus corculus 602 Leptoglossus fulvicornis 602 Leptoglossus occidentalis 602 Leptoglossus phyllopus 602 Leptoglossus zonatus 602 Leptothrips mali 628 Leptura spp. 568 lesser angle-wing katydid 48 lesser appleworm 545 lesser bulb fly 502 lesser canna leafroller 136 lesser clover leaf weevil 200 lesser house fly 510 lesser lawn leafhopper 290 lesser peachtree borer 426 lesser shothole borer 462 lesser vagabond crambus 124 lesser viburnum borer 426 lettuce aphid 256 lettuce root aphid 253, 322 lettuce root aphid 526 Leucage venusta 642 Leucoma salicis 88 Leucoptera laburnella 228

696

Lewis spider mite 314 light brown apple moth 132, 554 lightningbugs 618 lilac leafminer 228 lilac root weevil 196, 472 lilac rust mite 320 lilac-ash borer 344, 424 Lilioceris lilii 172 limabean pod borer 542 limabean vine borer 360 Limacus flavus 210 Limax maximus 210 Limenitis archippus 64 Limonius spp. 480 linden aphid 256 linden borer 442 linden leaf beetle 188 linden looper 106 linden spider mite 314 linden twiggall midge 420 linden wartgall midge 238 Lindorus lophanthae 612 lined June beetles 202, 468 Linepithema humile 522 Lipaphis pseudobrassicae 257 Liriomyza brassicae 214 Liriomyza trifolii 214 Liromyza huidobrensis 214 Liromyza sativae 214, 584 Listroderes costirostris 200 Listronotus oregonensis 476 Listrus spp. 566 Lithophane antennata 550 Lithophane unimoda 550 little billbug 478 lizard beetles 362 lobate lac scale 394 Lobesia botrana 554 Lochmaeus manteo 76 locust borer 440, 568 locust leafminer 218 locust twig borer 344 long-beaked clover aphid 253 longhorned beetles 354, 362, 440–447, 568 Longistigma caryae 257, 366 longjawed spider 642 longlegged flies 626 longrose gall wasp 416 longtailed dance fly 626 longtailed mealybug 260 loopers 102–109 Lophocampa argentata 150 Lophocampa caryae 88 Lophocampa harrisii 88 Lopholeucaspis japonica 390 Lopidea confluenta 592 Lopidea davisi 296, 592

INDEX lovebug 506 Loxagrotis albicosta 98 Loxosceles reclusa 646 Loxosceles rufescens 648 Loxostege cerealis 126 Loxostege sticticalis 126 lucerne flea 534 lucerne webworm 124 Lumbricus rubellus 540 Lumbricus terrestris 538 luna moth 80 Lycorma delicatula 400 Lygaeus angustomarginatus 598 Lygaeus kalmii 598 Lygus elisus 592 Lygus hesperus 592 Lygus lineolaris 592 Lymantria dispar 90 lynx spider 544 lyonetia leafminer 228 Lyonetia speculella 228 Lytta nuttalli 206 Lytta sayi 206 Macalla thrysisalis 144 Maconellicoccus hirsutus 262 Macremphytus tarsatus 162 Macremphytus testaceus 162 Macrodactylus subspinosus 202, 558 Macrodactylus uniformis 560 Macrohaltica ambiens 190 Macronoctua onusta 488 Macropsis fumipennis 288 Macropsis graminea 288 Macropsis ocellata 288 Macropsis trimaculata 288 Macrosiphoniella sanborni 256 Macrosiphum euphorbiae 248, 252, 366 Macrosiphum rosae 256, 366 Macrosteles quadrilineatus 288 Madeira cockroach 54 Madeira mealybug 262 madrone shield bearer 229 Magdalis spp. 340 Magicicada spp. 406–408 magnolia scale 380 mahogany webworm 144 Malacosoma americana 148 Malacosoma californica 148 Malacosoma constricta 150 Malacosoma disstria 150 Malacosoma incurva 150 Malacosoma tigris 150 Maladera castanea 470, 560 Mamara gulosa 556 Mamara spp. 356

Mamestra configurata 98 Manduca quinquemaculata 68 Manduca sexta 68 mantids 634 Mantis religiosa 634 manzanita leafgall aphid 322 maple bladdergall mite 332 maple callus borer 426 maple gouty veingall midge 236 maple leafcutter 120 maple leafhopper 286 maple leafminer 230 maple petiole borer 346 maple petiole borer 346 maple spider mite 314 maple spindlegall mite 332 maple trumpet skeletonizer 112 maple twig borer 342 marbled orbweaver 642 March flies 506 Margarodes meriodionalis 528 margined blister beetle 206 margined soldier beetle 566 marsh fly 506 marsh slug 208 Maskell scale 274 mason bees 364, 676 Matsucoccus acalyptus 274, 386 May beetles 202 May/June beetles 202, 466 McDaniel spider mite 312 meadow spittlebug 396 mealy plum aphid 252 mealybug destroyer 612 mealybugs 260–265, 374–375, 528, 604 Meditteranean fruit fly 578 Megachile rotundata 674 Megachile spp. 168, 364, 674 Megacopta cribraria 300 Megacyllene antennatus 440 Megacyllene caryae 440 Megacyllene robiniae 440, 566 Megalopyge opercularis 84 Megarhyssa spp. 662 Megaselia scalaris 510 Melanaspis obscura 392 Melanchra picta 98 Melanchroia chephise 108 Melanocallis caryaefoliae 256 Melanoplus bivittatus 42 Melanoplus devastator 42 Melanoplus differentialis 42 Melanoplus femurrubrum 42 Melanoplus sanguinipes 42 Meliarhizophagus fraxinifolii 257

Meliarhizophagus fraxinifolii 257, 258 Melitta cucurbitae 356 Meloe impressus 206 Meloe laevis 206 Meloe niger 206 melon thrips 306, 590 melonworm 560 Meredon equestis 502 Merhynchites bicolor 570 Merhynchites wickhami 570 Mermis nigriscens 670 Mesolecanium nigrofasciatum 380 mesquite borer 440 mesquite stinger 84 metallic wood borers 348–349, 432–439, 568 Metallus rubi 226 metamorphosis 18–19 Metarhizium anisopliae 670 Metcalfa pruinosa 400 Metolophium dirhodum 252 Mexican bean beetle 204 Mexican corn rootworm 482 Mexican fruit fly 578 Mexican mealybug 262 Micracantha sagittata 642 Micrathena funebris 642 Micrathena gracilus 642 Micrathena mitrata 642 Microcentrum retinerve 48 Microcentrum rhombifolium 48, 410 Microcrambus elegans 124 Microrhapala vittata 220 microsporidial diseases of insects 670 Microtheca ochroloma 176 Micrutalis calva 404 migratory grasshopper 42 Milax gagates 210 milkweed aphid 256 milkweed leaf beetle 178 milkweed longhorns 498 milkweed tussock moth 86 milky disease 668 millipedes 27, 532 mimosa webworm 142 Mindarus abietinus 368 mineola moth 552 mining bees 680 minute pirate bugs 632 Miscanthiococcus miscanthi 264 miscanthus mealybug 264 Mischocyttarus flavitarsis 654 Misumena vatia 636 Misumenoides formosipes 636

697

modest sphinx 72 mole crickets 512–515 monarch 64 Monarthropalpus flavus 224 Moneilema armatum 446 Monellia caryella 256 Monelliopsis pecanis 256 moneywort aphid 253 Monocesta coryli 184 Monochamus clamator 446 Monochamus scutellatus 446 Monochamus titillator 446 Monochroa fragariae 490 Monoctenus fulvus 156 Monoctenus melliceps 156 Monophadnoides geniculatus 160 Monoptilota pergratialis 360 Monostegia abdominalis 162 Mordella spp. 566 Mordellistena spp. 566 Mordwilkoja vagabunda 252, 322 morning glory plume moth 556 morning-glory leafminer 228 mossyrose gall wasp 416 moth flies 508 mottled tortoise beetle 181 mountain leafhopper 288 mountain pine beetle 458 mountain-ash sawfly 160 mourning cloak 66 Mozena spp. 604 mud daubers 658 mulberry whitefly 244 mullein bug 592 multicolored Asian lady beetle 610 Musca domestica 510 Myllocerus undecimpustulatus undata 198 Myrmica rubra 524 Mythimna unipuncta 98, 494 Myzocallis alhambra 256 Myzocallis coryli 257 Myzus ascalonicus 257 Myzus cerasi 252 Myzus persicae 248, 250–252 Nalepella halourga 320 Nalepella octonema 320 Nalepella tsugifoliae 321 Nanokermes pubescens 394 Nantucket pine tip moth 334 narcissus bulb fly 502 narrow-winged mantid 634 narrow-winged tree cricket Nasonovia ribisnigri 252

INDEX native elm bark beetle 454 native holly leafminer 220 native mole cricket 514 Naupactus cervinus 198 Naupactus leucoloma 476 Naupactus minor 476 Naupactus peregrinus 476 navel orangeworm 554 Nearctaphis bakeri 253 Nearctaphis crataegifoliae 253 needleminers 232–233 Nematocampa limbata 108 Nematocampla resistaria 108 nematodes parasites of insects 670 Nematus lipvskyi 158 Nematus ribesii 158 Nematus ventralis 158 Nemocestes incomptus 196 Neoclytus acuminatus 444 Neoclytus caprea 444 Neoclytus muricatulus 444 Neocurtilla hexadactyla 514 Neodactria caligosellus 124 Neodactria luteolellus 124 Neodiprion autumnalis 156 Neodiprion edulicolis 156 Neodiprion excitans 156 Neodiprion lecontei 154 Neodiprion pinetum 156 Neodiprion sertifer 154 Neodiprion swainei 156 Neodiprion tsugae 156 Neolecanium cornuparvum 380 Neoptilia malvacearum 164 Neoscona arabesca 642 Neoscona crucifera 642 Neoscona oaxacensis 642 Neotephritis finalis 578 Neoxabea bipunctata 48 Nephelodes minians 494 Nephila clavipes 640 Nepticula slingerlandella 228 Neuroterus quercusverrucum 234 Neuroterus saltatorius 234 Neurotoma asciata 152 Neurotoma inconspicua 152 Nevada buck moth 82 New England buck moth 82 New York weevil 198 Nezara viridula 595 Niesthrea louisianica 600 nightcrawler 538 nigra scale 384 Nipaecoccus aurilantus 262 Nipaecoccus nipae 262 Noctua pronuba 100

Nomophila nearctica 124 Norape ovina 84 Norape tenera 84 northern black widow 644 northern corn rootworm 176, 482 northern masked chafer 464 northern paper wasp 654 northern pine weevil 338 northern twostriped walkingstick 50 northern walkingstick 50 Norway maple aphid 257 Nosema locustae 670 notodontids 74–77 noxious bamboo mealybug 264 Nuclaspis californica 270 nuclear polyhedrosis viruses 668 nursery web spiders 638 nut weevils 574 Nuttall blister beetle 206 Nymphalis antiopa 66 Nymphuliella daekealis 120 Nysius spp. 299, 600 oak bark beetles 350 oak clearwing borer 426 oak lace bug 302 oak leaf itch mite 238 oak leafminers 228 oak leafroller 128 oak leaftier 128 oak lecanium 378 oak looper 108 oak mite 314 oak ribbed skeletonizer 110 oak rough bulletgall wasp 412 oak shothole leafminer 224 oak skeletonizer 110 oak sprout oberea 354 oak treehopper 404 oak twig pruner 354 oak webworm 128, 144 Oberea delongi 354 Oberea flavipes 362 Oberea gracilis 354 Oberea myops 354 Oberea ocellata 354 Oberea perspicillata 354 Oberea ruficollis 354 Oberea tripunctata 354 obliquebanded leafroller 130, 554 obscure mealybug 262 obscure root weevil 196, 474 obscure scale 392, 604 ocellate gall midge 238 Odonaspis ruthae 392

Odontopus calceatus 218 Odontota dorsalis 218 odorous house ant 522 Oecanthus fultoni 48 Oecanthus nigricornis 48, 410 Oecanthus niveus 48, 410 Oedaleonotus enigma 44 Oiketicus abbotii 116 oil beetles 206 okra caterpillar 100 oleander caterpillar 88 oleander pit scale 394 oleander scale 272 oleaster-thistle aphid 252 Olethreutes ferriferana 136 Oligonychus aceris 314 Oligonychus bicolor 314 Oligonychus boudreauxi 314 Oligonychus ilicis 314 Oligonychus milleri 314 Oligonychus newcomeri 314 Oligonychus platani 314 Oligonychus praetensis 316 Oligonychus subnudus 314 Oligonychus ununguis 312 Oligonychus viridis 314 Oligota oviformis 616 Oligotrophus betheli 418 Oligotrophus juniperi 418 omnivorous leafroller 134 omnivorous leaftier 136, 554 omnivorous loopers 108 Omphalocerca cariosa 144 Oncideres cingulata 252 Onciscus asellus 530 Oncopeltus fasciatus 598 Oncyolyda sitkensis 152 one-eyed sphinx 72 onespotted stink bug 596 onion bulb fly 502 onion maggot 500 onion thrips 306 Operophthera bruceata 108 Operophthera brumata 106 Ophiomyia kwanosis 216 Ophiomyia simplex 224 Ophyiulus spp. 532 opuntia bug 292 orange camellia rust mite 320 orange tortrix 132, 554 orangebanded arion 210 orangedog 60 orangehumped mapleworm 76 orangestriped oakworm 82 orbweaver spiders 640–643 orchard orbweavers 642 orchard spider 642 Orchestes alni 200, 216

698

Orchestes pallicornis 200, 216 Orchestes testaceus 200 organpipe mud dauber 658 oribatid mites 537 Oriental beetle 468 Oriental chestnut gall wasp 588 Oriental cockroach 54 Oriental fruit fly 578 Oriental fruit moth 344, 544 Orius spp. 632 Orthosia hibisci 548 Orygia antiqua 86 Orygia leucostigma 86 Orygia pseudotsugata 86 Orygia vetusta 86 Osmia lignaria 676 Osmia spp. 364 Ostrinia nubilalis 358, 542 Ostrinia penitalis 136 Otiorhynchus cribricollis 196 Otiorhynchus meridionalis 196, 472 Otiorhynchus ovatus 196, 472 Otiorhynchus rugosostriatus 196, 472 Otiorhynchus singularis 196, 472 Otiorhynchus sulcatus 196, 472 Oulema melanopus 172 Oxidus gracilis 532 Oxychilus alliarus 212 Oxychilus cellarius 212 Oxypodes salticus 644 Oxypodes scalaris 644 oystershell scale 388 Pachnaeus litus 474 Pachnaeus opalus 474 Pachylobius picivorous 340 Pachynematus setator 162 Pachypsylla celtidisastericus 326 Pachypsylla celtidisgemma 326 Pachypsylla celtidisinteneris 326 Pachypsylla celtidismamma 326 Pachypsylla celtidivescula 326 Pachysphinx modesta 72 Pachysphinx occidentalis 72 Pacific beetle cockroach 54 Pacific flatheaded borer 438 Pacific spider mite 314 Pacific tent caterpillar 150 Pacific willow leaf beetle 186 Paenibacillus larvae 668 Paenibacillus popilliae 668 painted bug 300 painted hickory borer 440 painted lady 62

INDEX painted leafhopper 290 pale legume bug 592 Paleacrita vernata 106 pales weevil 338 palestriped flea beetle 194 palm leaf skeletonizer 112 palmetto tortoise beetle 182 palmetto weevil 448 Pamphilius dentatus 152 Pamphilius persicus 152 Pamphilius phyllisae 152 Panchlora nivea 54 Pandemis limitata 134 Pandemis pyrusana 134 pandora moth 82 pandorus sphinx 70 Panonychus caglei 314 Panonychus citri 314 Panonychus ulmi 312 Panthaleus major 314 Papaipema leucostigma 358 Papaipema nebris 358 Papaipema nelita 358 paper wasps 654–657 Papilio brevicauda 60 Papilio cresophontes 60 Papilio glaucus 60 Papilio multicaudatus 60 Papilio polyxenes 58 Papilio rutulus 60 Papilio zelicaon 60 Paradiplosis tumifex 238 Paraleyrodes bondari 246 Paralobesia viteana 554 Paranadra brunnea 444 Paranapiacaba tricincta 176, 564 Paranthrene asilipennis 426 Paranthrene dollii 426 Paranthrene pellucida 426 Paranthrene robiniae 426 Paranthrene simulans 426 Parapediasia teterrella 124 Paraphlepsius strobi 286 Paraphytoptus chrysanthemi 321 Parapiesma spp. 296, 600 Paraprociphilus tessallatus 253, 368 Parasa indetermina 84 Parasaissetia nigra 384 parasitoids 660 Parasteatoda tepidariorum 644 Paratachardina pseudolobata 394 Parategeticula pollenifera 556 Parcoblatta spp. 54 parenthesis lady beetle 610

Paria fragariae 178 parsleyworm 58 Parthenolecanium corni 378 Parthenolecanium fletcheri 378 Parthenolecanium persicae 378 Parthenolecanium pruinosum 378 Parthenolecanium quercifex 378 pavement ant 520, 654 pea leaf beetle 198 pea leafminer 214 pea moth 544 peach sawfly 152 peach silver mite 321 peach twig borer 344, 554 peachtree borer 426, 486 Pealius azalaeae 244 pear decline disease 278 pear leafcurling midge 236 pear psylla 278 pear rust mite 320, 606 pear sawfly 166 pear thrips 306 pearleaf blister mite 332 pearslug 166 pecan carpenterworm 428 pecan cigar casebearer 118 pecan leaf casebearer 118 pecan leaf phylloxera 324 pecan leaf scorch mite 314 pecan leafroll mite 332 pecan nut casebearer 542 pecan phylloxera 324 pecan serpentine leafminer 216 pecan shoot curculio 350 pecan spittlebug 398 Peck’s skipper 140 Pediasia trisecta 122 Pegomya betae 222 Pegomya hyoscyami 222 Pegomya rubivora 356 pelecinid wasps 660 Pelecinus polyturator 660 Pelidnota punctata 202 Pemphigus busarius 253, 322, 526 Pemphigus populiramulorum 322 Pemphigus populitransversus 322 Pemphigus populivenae 253, 322, 526 Pemphredon spp. 364, 658 Pennisetia marginata 488 Pennsylvania leatherwing 616 Pentamerismus erythreus 319 Pentamerismus taxi 319 pepper maggot 578

pepper weevil 572 peppertree psyllid 328 Periclista albicollis 160 Peridroma saucia 94, 550 Perillus bioculatus 628 periodical cicadas 406–408 Periphyllus lyropictus 257 Periphyllus negundinis 257 Periplanata americana 54 Periplaneta australasiae 54 Periplaneta fulginosa 54 Periploca ceanothiella 420 Periploca nigra 336 petiolegall aphids 322, 526 Petrobia latens 314 Peucetia viridans 644 Phalacrococcus howertoni 268 Phalangium opilio 648 Phenacoccus dearnessi 372 Phenacoccus gossypii 226 Phenacoccus madeirensis 262 Phenococcus acericola 372 Phenococcus aceris 372 Phenococcus japonicus 372 Phenococcus solani 262 Phenococcus solenopsis 262 Phidippus audax 638 Philaenus spumarius 396 Philonix fulvicollis 234 Phloeosinus spp. 340 phlox plant bug 296, 592 phlox stem borer 362 Phobetron pithecium 84 Phoenix billbug 478 Phoracantha semipunctata 444 phorid flies 510 Phorodon cannabis 253 Phorodon humuli 253 Phryganidia californica 76 Phthorimaea operculella 496 Phyllaphis fagi 257, 258 Phyllobius intrusus 474 Phyllobius opalus 474 Phyllocnistis citrella 216 Phyllocnistis populiella 216 Phyllocnistis vitifoliella 216 Phyllocolpa bozemani 162 Phyllocoptella avellanae 333 Phyllocoptes didelphis 332 Phyllocoptes fructiphilus 320 Phyllocoptes gracilis 606 Phyllocoptes populi 332 Phyllocoptruta oleivora 321, 606 Phyllonorycter aceriella 230 Phyllonorycter blancardella 230 Phyllonorycter crataegella 230 Phyllonorycter elmaella 230 Phyllophaga crinita 468

699

Phyllophaga latifrons 468 Phyllophaga spp. 202, 466 Phylloteras poculum 234 Phyllotreta armoraciae 192 Phyllotreta cruciferae 192 Phyllotreta pusilla 192 Phyllotreta ramosa 192 Phyllotreta striolata 192 Phylloxera caryaecaulis 324 Phylloxera devastatrix 324 Phylloxera notabilis 324 Phylloxera russellae 324 phylloxerans 324 Phymata spp. 630 Physokermes hemicryphus 382 Physonota helianthi 182 Phytobia spp. 356 Phytomyza aquilegiana 222 Phytomyza aquilegivora 216 Phytomyza atricornis 222 Phytomyza chrysanthemi 222 Phytomyza columbinae 222 Phytomyza delphinivora 222 Phytomyza glabricola 220 Phytomyza ilicis 220 Phytomyza ililocola 220 Phytomyza verticillatae 220 Phytonemus pallidus 318 Phytophaga violicola 238 Phytoptus laevis 332 Phytoselius persimilis 650 pickleworm 550 picnic beetles 562 Pierce’s disease of grape 290 Pieris rapae 56 pigeon tremex 450 Pikonema alaskensis 156 pillbug 27, 530 pin oak clearwing borer 426 pin oak kermes 394 pine bark adelgid 370 pine bud mite 333 pine coneworm 543 pine false webworm 152 pine leaf adelgid 422 pine needle scale 270 pine needle sheathminer 232 pine oystershell scale 274 pine root collar weevil 474 pine sawyer 446 pine spittlebug 398 pine tortoise scale 382 pine tube moth 132 pine webworm 144 pine wilt nematode 446 pineleaf scale 270 Pineus pinifoliae 422 Pineus strobi 370

INDEX pink citrus mite 320, 606 pink hibiscus mealybug 262 pink-spotted hawk moth 72 pinkspotted lady beetle 610 Pinnaspis aspidistrae 274 pinyon needle scale 274, 386 pinyon pitch mass borer 336, 430 pinyon pitch nodulemaker 336 pinyon sawfly 156 pinyon spindlegall midge 238 pinyon stunt needlegall midge 238 pinyon tip moth 336 Pinyonia edulicola 238 pip gall wasp 588 Pissodes approximatus 338 Pissodes nemorensis 338 Pissodes strobi 338 pistol casebearer 118 pit scales 394 pitch midge 342 pitch twig moth 336, 430 pitcheating weevil 340 pitmaking pittosporum scale 394 Pityogenes spp. 340 Pityophthorus juglandis 350 Pityophthorus spp. 340 Plagiodera versicolor 186 Plagiognathus albatus 296 Plagiognathus punctatipes 296 Plagiognatus delicatus 296 Plagiometriona clavata 182 plains lubber 44 plains orbweaver 640 Planococcus citri 260, 604 plant bugs 294–297, 592, 632 plantain looper 102 plantanus spider mite 314 planthoppers 400–401 plasterer bees 678 Plateumaris spp. 188 Platycotis vittata 404 Platynota flavedana 132 Platynota idaeusalis 132 Platynota stultana 132, 554 Platypedia putnami 408 Platyptilia carduidactyla 556 Platytetranychus libocedri 314 Platytetranychus multidigituli 314 Platytetranychus thujae 314 Plecia nearctica 506 Plectodera scalator 498 Plinthocoelium suaveolens 498 plum curculio 568 plum gouger 570

plum leafhopper 288 plum rust mite 320 plum webspinning sawfly 152 plume moths 360 Plutella xylostella 110 Pococerca robustella 144 Podisus maculiventris 628 Podosesia aureocincta 424 Podosesia syringae 344, 424 Podura aquatica 534 Poecilocapsus lineatus 294 pole borer 444 Polistes annularis 654 Polistes dominula 654 Polistes exclamans 654 Polistes fuscatus 654 Polites peckius 140 Pollenia spp. 540 Polydrusus cervinus 196 Polydrusus formosus 196 Polydrusus impressifrons 196 Polygonia interrogationis 66 Polyphagotarsonemus latus 318 polyphagus shothole borer 462 polyphemus moth 80 Polyphylla comes 468 Polyphylla decemlineata 468 Polyphylla hammondi 468 Polyphylla spp. 202 Polyphylla variolosa 468 ponderosa pine needleminer 232 ponderosa pine spider mite 314 ponderosa pine tip moth 336 Pontania proxima 236 Pontia protodice 56 Popillia japonica 202, 466, 558 poplar and willow borer 448 poplar blackmine beetle 220 poplar borer 442 poplar budgall mite 333 poplar carpenterworm 428 poplar dagger moth 88 poplar leaf aphid 256 poplar leaffolding sawfly 162 poplar petiolegall aphid 322 poplar tentmaker 150 poplar twig borer 354 poplar twiggall aphid 322 poplar twiggall fly 420 poplar vagabond aphid 252, 322 poplar-gall saperda 442 Porcellio laevis 530 Porcellio scaber 530 potato aphid 248, 252, 366 potato flea beetle 194, 484 potato leafhopper 282 potato psyllid 276

potato tuberworm 496 potter wasps 656 prairie crayfish 531 prairie walkingstick 50 prairie yellowjacket 586, 656 praying mantid 634 predatory ants 654 predatory midges 624 predatory mites 650 predatory plant bugs 632 predatory snails 652 predatory stink bugs 628 predatory thrips 628 prickly pear cactus moth 430 Prionoxystus robiniae 428 Prionus californicus 498 Prionus imbricornis 498 Prionus laticollis 498 Pristophora abbreviata 160 Pristophora aquiligae 160 Pristophora erichsonii 160 Pristophora serrula 160 Pritchard ground mealybug 528 privet mite 319 privet rust mite 320 privet thrips 306 Procambarus gracilis 531 Prociphilus americanus 253, 258 Prociphilus caryae 258 Prociphilus tesselatus 258 Profenusa canadensis 226 promethea moth 80 prominent moths 74–77 Prosapia bicincta 396 Protaphis middletoni 522, 526 Proteoteras aesculana 342 Proteoteras arizonae 342 Proteoteras crescentana 342 Proteoteras willingana 342 Protopluvinaria pyriformis 268 prowling spiders 646 Pryeria sinica 112 Pseudococcus calceolariae 262 Pseudococcus comstocki 262 Pseudococcus longispinus 260 Pseudococcus maritimus 372, 604 Pseudococcus viburni 262, 604 Pseudopityophthorus spp. 350 Psila rosae 504 Psyche casta 116 Psychoda spp. 508 psylla shock 278 psyllids 276–281, 326–329 Psyllobora spp. 612 Psylloides punctulata 194 Psyllopsis discrepans 280, 328

700

Psyllopsis fraxinicola 280 Pterocomma bicolor 366 Pterocomma pseudopopueum 366 Pterocomma smithiae 257, 366 Pterophylla camellifolia 48 Pulvinaria acericola 266, 382 Pulvinaria floccifera 266, 382 Pulvinaria innumerabilis 382 purple scale 274 purple-backed cabbageworm 126 purslane leafminer 226 puss caterpillar 84 Putnam cicada 408 Pycnoscelus surinamensis 54 Pyemotes herfsi 238 pyramidal fruitworm 560 pyriform scale 268 Pyrrhalta viburni 186 Pyrrharctia isabella 92 Quadraspidiotus juglansregiae 392 Quadraspidiotus perniciosus 390, 604 queen butterfly 64 question-mark butterfly 66 rabid garden spider 638 Rabidosa rabida 638 radish maggot 500 raspberry bud weevil 196 raspberry cane borer 354 raspberry cane maggot 356 raspberry crown borer 488 raspberry fruitworms 564 raspberry horntail 346 raspberry red mite 314 raspberry sawfly 160 rattailed maggot 624 recluse spiders 648 red admiral 62 red carpenter ant 522 red lettuce aphid 252 red lily beetle 172 red oak clearwing borer 426 red palm weevil 448 red sunflower seed weevil 572 red turnip beetle 176 red turpentine beetle 458 red wax scale 384 red wriggler 540 redbacked cutworm 494 red-banded leafhopper 290 redbanded leafroller 132, 554 redbanded thrips 308 redbay ambrosia beetle 460

INDEX redbay psyllid 328 redberry mite 606 redbud leaffolder 136 redgum lerp psyllid 280 redheaded flea beetle 194 redheaded pine sawfly 154 redheaded sharpshooter 290 redhumped caterpillar 76 redhumped oakworm 76 redlegged grasshopper 42 rednecked cane borer 348 red-shouldered bug 600 redshouldered stink bug 596 resplendent shield bearer 229 Resseliella clavula 420 Reticulitermes flavipes 516 Reticulitermes tibialis 516 Reticulitermes virginicus 516 Retinia albicapitana 336 Retinia arizonensis 336 Retinia comstocki 336, 430 Retinia metallica 336 Rhabdophaga rigidae 418 Rhabdophaga strobiloides 418 Rhabdopterus picipes 178 Rhagoletis cingulata 576 Rhagoletis completa 576 Rhagoletis fausta 576 Rhagoletis indifferens 576 Rhagoletis mendax 576 Rhagoletis pomonella 576 Rhamphomyia longicauda 626 Rhizoglyphus echinops 536 Rhizoglyphus hyacinthi 536 Rhizoglyphus robini 536 Rhizoglypus engeli 536 Rhizotrogus majalis 466 Rhodesgrass mealybug 264 rhododendron borer 344, 426 rhododendron lace bug 302 rhododendron whitefly 244 Rhopalapion longirostre 574 Rhopalomyia californica 238 Rhopalomyia chrysanthemi 238 Rhopalosiphum insertum 253 Rhopalosiphum maidis 257 Rhopalosiphum nymphaeae 253 Rhopalosiphum padi 253 Rhopalosiphum rufiaabdominalis 257, 528 Rhopobota naevana 132, 554 Rhyacionia buoliana 334 Rhyacionia bushnelli 336 Rhyacionia frustrana 334 Rhyacionia neomexicana 336 Rhychophorus cruentatus 448 Rhychophorus ferrugineus 448 Rhyncothrips ilex 306

Rhyparobia maderae 54 ribbed bud gall 414 rice root aphid 257, 528 ridged bunch gall wasp 414 ringlegged earwig 52, 636 robber flies 626 robust ground crickets 46 Rocky Mountain billbug 478 Rocky Mountain juniper aphid 256 Rodalia cardinalis 612 roly-poly 530 roly-poly hunter 640 Romalea guttata 44 root maggots 500 root weevils 196, 472–475 rose aphid 256, 366 rose blistergall wasp 234 rose chafer 202, 558 rose curculio 570 rose grass aphid 252 rose leafhopper 284 rose midge 356, 582 rose rosette disease 320 rose shoot sawfly 346 rose stem girdler 348 rose tip sawfly 346 rose tortrix 128 roseroot gall wasp 416 roseslug 166 rosy apple aphid 252 rosy predator snail 212, 652 rough stink bug 595 rough strawberry root weevil 196, 472 roundheaded appletree borer 442 roundheaded borers 354, 362, 440–447 rove beetles 616 royal moths 78–83 royal palm bug 296 rubber rabbitbrush beetle 178 rudbeckia leafspot psyllid 280 rugose spiraling whitefly 246 Rumina decollata 212, 652 rust mites 320–21 rusty plum aphid 252 rusty tussock moth 86 Sabulodes aegrotata 108 Sabulodes caberata 108 saddleback caterpillar 84 saddled prominent 76 sago scale 274 Saissetia coffae 384 Saissetia oleae 384 Salticus scenicus 638

saltmarsh caterpillar 92 San Jose scale 390, 604 Sancassania anomala 536 sandhill chafer 470 sap beetle 562 Saratoga spittlebug 398 sarcophagid flies 666 Sarucallis kahawaluokalani 257 sassafras borer 354 satin moth 88 sawflies 152–167, 236, 346, 360, 416, 558 Say blister beetle 206 Say stink bug 596 scale insects (armored) 270–275, 388–393, 604 scale insects (cochineal) 264 scale insects (eriococcid) 374–377 scale insects (falsepit) 394–395 scale insects (kermes) 394–395 scale insects (margarodid) 274, 386–387, 528 scale insects (pit) 394–395 scale insects (soft) 266–271, 378–385 Scaphoideus luteolus 280 Scaphytopius acutus 288 Scaphytopius irroratus 288 Scapteriscus abbreviatus 512 Scapteriscus brellii 512 Scapteriscus vicinus 512 scarlet oak sawfly 166 Scatella stagnalis 508 Schizocerella lineata 164 Schizocerella pilicornis 164, 226 Sciophithes obscurus 196, 474 Scirtothrips citri 590 Scirtothrips dorsalis 308 Scirtothrips perseae 590 scoliid wasps 660 Scolopendra spp. 652 Scolothrips sexmaculatus 628 Scolytus multistriatus 454 Scolytus quadrispinosus 452 Scolytus rugulosus 452 Scolytus schevyrewii 454 Scudderia spp. 48 scurfy scale 390 Scutigera coleoptrata 652 Scutigerella immaculata 536 Scyphophorus acupunctatus 448 Scyphophorus yuccae 448 seedcorn maggot 500 sequoia pitch moth 426 serpentine leafminer 214 Sesia apiformis 488 Sesia tibialis 488

701

Setoptus strobacus 321 sevenspotted lady beetle 610 shallot aphid 257 shamrock orbweaver 642 shield bearers 229 Shivaphis celti 257 Shivaphis graminum 257, 258 Shizura concinna 76 Shizura ipomoeae 76 Shizura unicornis 76 Shoene spider mite 312 shore earwig 52 shore flies 508 short-tailed swallowtail 60 shortwinged mole cricket 512 shothole borer 452 Sibene stimulea 84 side-swimmers 532 silver garden spider 640 silverspotted skipper 138 silverspotted tiger moth 150 silver-striped webworm 124 Sinea diadema 630 Singhiella simplex 246 singular black lady beetle 612 sinuate peartree borer 436 Siphonius phillyreae 242 Sirex noctilio 450 sirex woodwasps 450 Sitobion avenae 257 Sitona lineatus 198 sixspotted leafhopper 288 sixspotted nursery spider 638 sixspotted thrips 628 skeletonizers 110–113 skippers 138–141 slug caterpillars 84 slug sawflies 166–167 slugs 208–211 small carpenter bees 364, 676 small fruit flies 510, 580–583 small milkweed bug 598 small mulberry borer 354 small spruce bud scale 382 smaller European elm bark beetle 454 smaller yellow ant 522 Smerinthus cerisyi 72 Smerinthus jamaicensis 72 Smicronyx fulvus 572 Smicronyx sordidus 572 Sminthurus viridis 534 smokybrown cockroach 54 snailcase bagworm 116 snails 208, 212–213 snapdragon plume moth 556 snout mites 650 snowball aphid 252

INDEX snowberry clearwing 72 snowbush spanworm 108 snowy urola moth 124 soapberry borer 436 soapberry bug 600 sod webworms 122–125, 496 soft scales 266–271, 380–385 soft-winged flower beetles 566, 616 soil centipedes 652 solanum mealybug 262 soldier beetles 566, 616 Solenopsis invicta 518 solenopsis mealybug 262 Solenopsis richteri 520 Solenopsis xyloni 520 Sonoran tent caterpillar 150 sooty molds 28, 240 southeastern field cricket 46 southeastern gray twig pruner 354 southeastern subterranean termite 516 southern armyworm 96 southern black widow 644 southern cabbageworm 56 southern chinch bug 298 southern corn rootworm 174, 484, 564 southern fire ant 520 southern garden leafhopper 284 southern garden slug 210 southern ground cricket 46 southern masked chafer 466 southern mole cricket 512 southern pecan leaf phylloxera 324 southern pine beetle 456 southern pine coneworm 430, 552 southern pine sawyer 446 southern red mite 314 southwestern masked chafer 466 southwestern pine tip moth 336 southwestern tent caterpillar 150 sowbugs 27, 530 soybean looper 104 Spanish moth 490 spanworms 106–109 sparganothis leafroller 134 Sparganothis sulfureana 134 speckled green fruitworm 548 Speranza ribearia 108 Sperry’s lawn moth 124 Sphenophorus cicatristriatus 478 Sphenophorus coesifrons 478 Sphenophorus minimus 478 Sphenophorus parvulus 478

Sphenophorus phoeniciensis 478 Sphenophorus venatus vestitus 478 Sphinx chersis 70 sphinx moths 68–73 spider mite destroyers 610, 616 spider mites 310–317 spider wasps 660 spiders 636–649 Spilonota ocellana 130, 554 spinach flea beetle 190 spinach leafminer 222 spined assassin bug 630 spined micrathena 642 spined soldier bug 628 spined turban gall 234 spine-tailed earwigs 636 spiny elm caterpillar 66 spiny oak sawfly 160 spiny oak slugs 84 spiny oakworm 82 spiny witch-hazel gall aphid 252, 322 spinybacked orbweaver 642 spinyrose gall wasp 234 spirea aphid 252 Spissistilus festinus 402 spittlebugs 396–399 Spodoptera eridiana 96 Spodoptera exigua 96 Spodoptera frugiperda 94–96 Spodoptera ornithogalli 96 Spodoptera praefica 96 spotted asparagus beetle 564 spotted blister beetle 206 spotted cucumber beetle 174, 484, 564 spotted cutworm 98 spotted flower buprestids 568 spotted lanternfly 400 spotted oleander caterpillar 88 spotted pelidnota 202 spotted pine sawyer 446 spotted snake millipede 532 spotted-wing drosophila 580 spring cankerworm 106 spring field cricket 46 springtails 26, 534 spruce beetle 458 spruce gall midge 342 spruce needleminer 130, 232 spruce rust mite 320 spruce spider mite 312 squash bees 678 squash beetle 204 squash bug 292, 604 squash vine borer 356 Sri Lanka weevil 198

Stagmomantis californica 634 Stagmomantis carolina 634 Stagmomantis floridensis 634 Stagmomantis limbata 634 stalk borer 358 Steatoda borealis 644 Steatoda grossa 644 Steatoda triangulosa 644 steel-blue cricket killer 658 steel-blue grapevine flea beetle 190 Stelidota geminata 562 Stenopelmatus fusca 514 Stenoptilodes antirrhina 556 Stephanitis pyrioides 302 Stephanitis rhododendri 302 Stephanitis takeyai 302 Stethorus spp. 610 Stictocephala bisonia 402 Stigmella juglandifoliella 216 stinging caterpillars 82, 84 stinging rose caterpillar 84 stink bugs 300–301, 594–597, 628 Stomacoccus platani 272, 386 stone centipedes 652 Strauzia longipennis 364 strawberry aphid 257 strawberry bud weevil 572 strawberry crown borer 476 strawberry crown moth 490 strawberry crownminer 490 strawberry flea beetle 190 strawberry leafroller 134 strawberry root weevil 196, 472 strawberry rootworm 178 strawberry sap beetle 562 strawberry spider mite 312 Strigoderma arboricola 470, 558 striped blister beetle 206 striped cucumber beetle 174, 484, 564 striped flea beetle striped grass looper 104 striped ground cricket 46 striped lynx spider 644 striped mealybug 264 striped pine scale 380 striped sod webworm 124 striped tortoise beetle 181 stubby needlegall midge 238 Subcoccinella vigintiquatuorpunctata 204 subterranean termite 516 succulent oak gall wasp 234 sugarbeet root aphid 253, 322, 526 sugarbeet root maggot 502

702

sugarcane beetle 468 sulfur butterflies 56 sumac flea beetle 192 sumac leafroller 136 sumac psyllid 278 sumac stem borer 354 sunflower aphid 252 sunflower beetle 178 sunflower headclipping weevil 572 sunflower maggot 364 sunflower midge 584 sunflower moth 542 sunflower seed maggot 578 sunflower stem weevil 362 sunflower tortoise beetle 182 Supella longipalpa 54 Surinam cockroach 54 Swaine jack pine sawfly 156 swallowtails 58–61 sweat bees 680 swede midge 364 sweetgum scale 272 sweetpotato flea beetle 194 sweetpotato hornworm 72 sweetpotato leaf beetle 176 sweetpotato weevil 476 sweetpotato whitefly 242–244 sycamore leaffolder 134 sycamore plant bug 296 sycamore scale 274, 386 sycamore seed head bug 600 sycamore tussock moth 88 Symmerista canicosta 72 Symmerista leucitys 76 symphylans 536 Synanthedon acerni 426 Synanthedon bibionipennis 490 Synanthedon exitiosa 426, 486 Synanthedon latifera 426 Synanthedon pictipes 426 Synanthedon pini 426 Synanthedon pyri 426 Synanthedon rhododendri 344, 426 Synanthedon scitula 426 Synanthedon sequoiae 426 Synanthedon tipuliformis 344 Synanthedon viburni 344, 426 Synobabus bipustulatus 200 Syntomeida epilais 88 syrphid flies 624 Systena blanda 194 Systena elongata 194 Systena frontalis 194 tachinid flies 666 Taeniothrips inconsequens 306

INDEX Talitroides allaudi 532 Talitroides topitotum 532 Tamalia coweni 322 Taniva albolineana 130, 232 Tapinoma melanocephalum 654 Tapinoma sessile 522 tarnished plant bug 592 tarsonemid mites 318 tawny emperor 66 tawny garden slug 210 tawny mole cricket 512 Taxodiomyia cupressi 584 Taxodiomyia cupressiianassa 238, 418 taxus bud mite 333 taxus weevil 472 tea scale 272 Tegenaria domestica 646 Tegeticula yucasella complex 556 Tehama bonifatella 124 Telamona decorata 404 Telamona reclivata 404 Teleonemia scrupulosa 302 Tenodera angustipennis 634 Tenodera aridifolia sinensis 634 tent caterpillars 148–151 tentiform leafminers 230 Tenuipalus orchidarum 319 Tenuipalus pacificus 319 termites 516 terrapin scale 380 tessellated scale 268 Tetanops myopaeformis 502 Tethida cordigera 160 Tetraleurodes mori 244 Tetramorium caespitum 520, 654 Tetraneura ulmi 322 Tetranychus canadensis 312 Tetranychus humorous 314 Tetranychus magnoliae 314 Tetranychus mcdanieli 312 Tetranychus pacificus 314 Tetranychus schoenei 312 Tetranychus turkestani 312 Tetranychus urticae 310 Tetraopes femoratus 498 Tetraopes tetrophthalmus 498 Tetraopes texanus 498 Texas field cricket 46 Texas leafcutting ant 168 Thaumatopsis pexellus 124 Theba pisana 212 Thecabius lysimachiae 253 Thecabius populiconduplifolius 253 Thecodiplosis liriodendra 238

Thelia bimaculata 404 thistle aphid 252 thistle caterpillar 62 thistle tortoise beetle 182 thorn bugs 404 thousand cankers disease 350 threadlegged bug 630 threebanded leafhopper 286 threebanded slug 210 threelined leafroller 134 threespotted flea beetle 190 thrips 25, 304–309, 590–591, 628 Thrips calcaratus 306 Thrips hemerocallis 304 Thrips palmi 306, 590 Thrips simplex 304, 590 Thrips tabaci 304 Thyanta custator 596 Thyanta pallidovirens 596 Thymelicus lineola 140 Thyridopteryx ephemeraeformis 114 Thysanopyga intractata 106 Tibicen spp. 408 tiger beetles 614 tiger swallowtails 60 Tinocallis saltans 257 Tinocallis ulmifolii 257 tiphiid wasps 660 Tipula oleracea 506 Tipula paludosa 506 tobacco budworm 546 tobacco flea beetle 194 tobacco hornworm 68 tobacco stalk borer 362 tobacco thrips 308 tobacco thrips 590 Tomarus gibbosus 470 tomatillo fruitworm 546 tomatillo leaf beetle 172 tomato bug 592 tomato fruitworm 548 tomato hornworm 68 tomato pinworm 554 tomato psyllid 276 tomato russet mite 320 tomato spotted wilt virus 590 Tomicus piniperda 340 Tomostethus multicinctus 158 toothed flea beetle 194 tortoise beetles 180–183 Toumeyella lirodendri 382 Toumeyella parvicornis 382 Toumeyella pini 380 Toumeyella pinicola 382 Toxoptera aurantii 257 Toxoptera citricidus 257

toyon thrips 306 Trachelipus rathkii 530 translucent oak gall wasp 234 tree crickets 46–49, 410 treehoppers 402–405 Tremex columba 450 Trialeurodes abutilonea 244 Trialeurodes vaporariorum 242–243 triangulate cobweb spider 644 Trichiosoma triangulum 164 Trichiosoma viminalis 164 Trichobaris mucorea 362 Trichobaris trinotata 362 Trichochorous spp. 566 trichogramma wasps 664 Tricholochmaea decora carbo 186 Trichoplusia ni 102 Tridiscus sporoboli 264 Trionymus sp. 264 Trioza alacris 328 Trioza eugeniae 328 Trioza magnoliae 328 Trirhabda bacharidis 178 Trirhabda nitidicollis 178 Trirhabda virgata 178 Trisecatus campnodus 333 Trisecatus cupressi 333 Trisecatus gemmavitians 333 Trisecatus juniperinus 333 Trisecatus pini 333 Trisecatus thujivagrans 333 tropical sod webworm 124 Tropidosteptes amoenus 296 Tropidosteptes brooksii 296 Tropidosteptes illitus 296 Tropidosteptes pacificus 296 true katydid 48 tuber flea beetle 194, 484 Tuberolachnus salignis 257, 366 tufted apple bud moth 132 tulip bulb aphid 257, 526 tuliptree scale 382 tuliptree silkmoth 80 tumbling flower beetles 566 turfgrass scale 268 turnip aphid 257 tussock moths 86–89 twicestabbed lady beetle 610 twicestabbed stink bug 596 twig beetle 340 twig girdler 352 twinspotted sphinx 72 twobanded Japanese weevil 198 twolined chestnut borer 436 twolined spittlebug 396 twomarked treehopper 402

703

twospotted lady beetle 610 twospotted spider mite 310 twospotted stink bug 628 twospotted tree cricket 48 twostriped grasshopper 42 twostriped planthopper 400 twostriped walkingstick 50 two-tailed swallowtail 60 Tyloderma fragariae 476 Tylonotus bimaculatus 446 Typhlocyba pomaria 286 Typhlodromus pyri 650 Typocerus spp. 568 Typophorus nigritus 176 Udea profundalis 126 Udea rubigalis 126 uglynest caterpillar 144 Uhler stink bug 596 Umbonia crassicornis 404 umbrella pine scale 274 Unaspis euonymi 272, 390 underwing moths 100 unicorn caterpillar 76 Urbanus proteus 140 Uresiphita reversalis 136 Urola nivalis 124 Uroleucon ambrosiae 257 Uroleucon rudbeckiae 257 Uroleucon spp. 366 Urophora cardui 418 Utamphorphora crataegi 257 vagabond crambus 124 valley grasshopper 44 Vanessa annabella 64 Vanessa atalanta 62 Vanessa cardui 62 Vanessa virginiensis 64 variable oakleaf caterpillar 76 variegated cutworm 94 variegated fritillary 66 variegated lady beetle 610 variegated leafhopper 286 variegated leafroller 132 vedalia beetle 612 vegetable leafminer 214, 584 vegetable weevil 200 velvet mites 650 velvetbean caterpillar 100 Vespa crabro germana 588, 656 Vespa mandarinia 588 Vespula flaviposa 586 Vespula germanica 586, 656 Vespula maculifrons 596, 656 Vespula pensylvanica 586, 656 Vespula squamosa 586, 656 viburnum borer 344, 426

INDEX viburnum leaf beetle 186 viburnum stem sawfly 346 viceroy butterfly 64 vinegar flies 510, 580–583 violet gall midge 238 violet sawfly 160 viral diseases of insects 668 Virginia creeper clearwings 490 Virginia creeper leafhopper 286 Virginia creeper sphinx 70 Vitacea polistiformis 490 Vitacea scepsiformis 490 walkingsticks 50–52 walnut blister mite 332 walnut caterpillar 74 walnut husk fly 578 walnut lace bug 302 walnut scale 392 walnut shoot moth 344 walnut sphinx 70 walnut twig beetle 350 waterlily aphid 253 waterlily leaf beetle 188 waterlily leafcutter 120 waved sphinx 70 wax scales 268, 384 webbing coneworm 543 webspinnng sawflies 152 webworms 122–130, 142–147 weeping fig thrips 308 west coast lady 64 western apple leafhopper 286 western ash plant bug 296 western aster root aphid 526 western bean cutworm 98 western black flea beetle 192 western boxelder bug 598 western cherry fruit fly 578 western chinch bug 298 western conifer-seed bug 602 western corn rootworm 482, 564 western erineum maple mite 333 western flower thrips 308, 590 western grapeleaf skeletonizer 112

western lawn moth 124 western lynx spider 644 western masked chafer 466 western pine cone weevil 574 western pine shoot borer 336 western pine spittlebug 398 western pine tip moth 336 western poplar agrilus 436 western poplar clearwing 426 western potato flea beetle 194, 484 western potato leafhopper 284 western predatory mite 650 western raspberry fruitworm 564 western rose chafer 560 western rose curculio 570 western spotted cucumber beetle 174, 484, 564 western spotted orbweaver 642 western striped cucumber beetle 174, 484, 564 western striped flea beetle 192 western subterranean termite 516 western tarnished plant bug 592 western tent caterpillar 148 western tiger swallowtail 60 western tussock moth 86 western X-disease 288 western yellowjacket 586, 656 western yellowstriped armyworm 96 westrn black widow 644 wheat curl mite 320, 332 wheat stem sawfly 360 wheel bug 630 whirligig mites 650 white butterflies 56 white flannel moth 84 white garden snail 212 white grubs 464–471 white micrathena 642 white muscardine disease 670 white pine sawfly 156 white pine sheath mite 321

white pine weevil 338 whitebanded elm leafhopper 290 whiteflies 242–247 whitefringed weevils 198, 474 whitelined sphinx 70 whitemarked tussock moth 86 whitespotted sawyer 446 Willamette mite 314 willow beakedgall midge 418 willow conegall midge 418 willow flea weevil 218 willow redgall sawfly 236 willow sawfly 158 willow scale 392 willow shoot sawfly 346 willow-carrot aphid 252 wilt disease of insects 668 winter grain mite 316 winter moth 106 wireworms 480 witch-hazel leafgall aphid 322 wolf spiders 638 wood louse hunter 640 woods cockroaches 54 woods weevil 196 wool carder bee 676 wool sower gall wasp 414 woolly alder aphid 253, 258, 368 woolly apple aphid 252, 258, 368, 526 woolly beech aphid 257, 258 woolly elm aphid 252, 526 woolly elm bark aphid 258, 368 woolly hawthorn aphid 252, 258, 368 woolly pear aphid 252, 258, 368 woolly pine adelgids 370 woolly whitefly 246 woollybear gall wasp 234 woollybears 92 Xanthogaleruca luteola 184 Xanthogaleruca nymphaeae 186 Xanthopastis timais 490 Xestia c-nigrum 98

704

Xestia dolosa 98 Xlastodoris luteolus 296 Xyleborus glabratus 462 Xyleborus saxensi 462 Xylella fastidiosa 290 Xylocopa spp. 364 Xylocopa virginica 674 Xylosandrus compactus 462 Xylosandrus crassiusculus 460 Xylosandrus germanus 460 yaupon psyllid 328 yellow pecan aphid 256 yellow poplar weevil 218 yellow scale 604 yellow spider mite 314 yellow woollybear 92 yellowheaded spruce sawfly 156 yellowjackets 586–589, 656 yellowlegged paper wasp 654 yellow-legged sac spider 646 yellowmargined leaf beetle 176 yellownecked caterpillar 74 yellownecked flea beetle 190 yellow-soled slug 210 yellowstriped armyworm 96 yellowstriped fruitworm 550 yucca moths 556 yucca plant bug 296 yucca weevil 448 Zachrysia provisoria 212 Zadiprion townsendi 156 Zaprionus indianus 582 zebra caterpillar 98 zebra chip disease 276 zebra jumper 638 Zelleria haimbachi 230 Zelus pp. 630 Zeugophora scutellaris 220 Zeuzera pyrina 428 zic-zac leafhopper 286 Zimmerman pine moth 430 Zonosemata electa 578 zoysiagrass mite 333 Zygogramma exclamationis 178