Diagnosing Plant Problems: Insects and Other Arthropods Hodges and Ellis. December Update, August NPDN Publication No. 0008

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Insect Diagnosis  Focuses on classic, morphology based taxonomy.  Often requires an expert taxonomist for species-level identification.  Limited resources for diagnosticians.  Quality of sample submitted is important!

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods How is an Insect Identified to Species? First Detectors (County Extension Agents, Crop Consultants)  Extension Diagnostic Specialists (at Land Grant Universities)  Taxonomic Specialists (usually federal, state, or university employees)  Species Identification Confirmed

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms of Damage Over-development of tissues Necrosis of tissue Types of arthropod feeding damage - Stippling - Chlorosis - Sooty Mold - Leafmining - Leaf Defoliaters - Spider Mites - Borers - Root Damage Photo 1: Paul Weston, Cornell University, Photo 2: Jim Occi, BugPics, Photo 3: Petr Kapitola, Forestry and Game Management Research Institute - Czechia, Photo 4: Jerald E. Dewey, USDA Forest Service,

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Over-development of tissues Some insect and mite species can induce gall formation on a variety of host plant structures. Gall-makers are generally host plant specific. A mite gall, Aculops laevigata on willow Photo: William M. Ciesla, Forest Health Management International, Photo: Petr Kapitola, Forestry and Game Management Research Institute - Czechia, Gall Mite Damage Eyespot Gall

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Over-development of tissues How do you know if an insect has caused this damage? Closely examine plant deformation. Cut open gall. Exit holes, frass, empty larval chambers, etc. Rear insects to adult stage.  Photo: Ronald F. Billings, Texas Forest Service, cynipid gall wasps Photo: Jerry A. Payne, USDA Agricultural Research Service, oriental chestnut gall wasp

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Over-development of tissues Can insect or mite galls cause serious damage to host plants? Yes, heavy infestations can negatively effect overall plant health and reduce the aesthetic value of ornamental crops. ash flower gall mite damage Photo: A. Steven Munson, USDA Forest Service,

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Over-development of tissues  Non-insect bacterial and fungal galls may resemble insect galls.  Crown gall bacterium causes galls on roots, crowns and stems.  Fungi can also form large galls that superficially resemble the crown gall bacterium. Photo: USDA Forest Service - Ogden Archives, USDA Forest Service, bacterial gall on douglas-fir

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Necrosis of tissue Dieback-insect damage Feeding damage from several types of insects can lead to limb dieback. Death of the host may result.   Loblolly pine killed by southern pine beetle larch casebearer damage Top Photo: Petr Kapitola, Forestry and Game Management Research Institute - Czechia, Bottom Photo: Ronald Billings. Texas Forest Service.

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Types of Insect Feeding Damage  Insects with piercing- sucking mouthparts cause stippling and/or chlorosis on the host.  Example groups: aphids, true bugs, hoppers, scale insects, whiteflies, etc. Azalea lace bug damage Top Photo: Clemson University - USDA Cooperative Extension Slide Series, Bottom Photo: John A. Weidhass, Virginia Polytechnic Institute and State University, wax scale

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Types of Insect Feeding Damage Presence of sooty mold may suggest an infestation of honeydew producing insects such as scales, mealybugs, whiteflies, or aphids. Presence of ants may also be an indicator of these insects! Photo: Scott Tunnock, USDA Forest Service, sooty mold on grand fir

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Types of Insect Feeding Damage Leafmining Insects that produce characteristic “mines” in leaves by feeding. Formed by various insects including flies, wasps, moths, and beetles. Aspen blotchminer Bottom Photo: Minnesota Department of Natural Resources Archives, Minnesota Department of Natural Resources. columbine leafminer Top Photo: Lisa Ames, UGA,

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Types of Insect Feeding Damage Leaf Defoliaters Damage caused to a plant by insect feeding. “Skeletonizing” results when the veins or the “skeleton” of the leaf is left behind. Bottom Photo: E. Bradford Walker, Vermont Department of Forests, Parks and Recreation, maple trumpet skeletonizer oak skeletonizer Top Photo: James Solomon, USDA Forest Service,

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Types of Arthropod Feeding Damage Spider Mites Leaf damage includes flecking, bronzing, and/or scorching of leaves. Several natural enemies. Most problematic in heavy insecticide use areas. gorse spider mite damage Photo: Eric Coombs, Oregon Department of Agriculture, twospotted spider mite Photo: Mississippi State University Archives, Mississippi State University,

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Types of Insect Feeding Damage Borers Insects that bore into a host trunk, stem, or twig as part of their life cycle. Damage often results in weakening or killing the host. A Lepidopteran stalk borer, Papaipema nebris, in silver maple Photo: James Solomon. USDA Forest Service.

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Signs and Symptoms Types of Insect Feeding Damage Roots Don’t forget to look for potential insect damage on roots! Aspen root girdler Bottom Photo: Robert L. Anderson, USDA Forest Service, Scarab beetle larval feeding damage on root system of pine Top Photo: Ostry, Mike. USDA Forest Service.

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Insect Identification Know Common Pest Arthropod Groups! Numerous lepidopteran caterpillars (ex. armyworms, cutworms) Beetles (Order Coleoptera): numerous leaf- feeding and wood-boring pests Sawflies (Order Hymenoptera) Various flies (Order Diptera) Various insects with piercing-sucking mouthparts including scales, mealybugs, whiteflies, aphids, psyllids, hoppers, various other members of the Order Hemiptera. Spider Mites

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Insect Identification Know the difference between pests and beneficials! There are several predatory or parasitic beneficial insects! Pest - southern green stink bug Top Photo: David Cappaert, Beneficial-a predatory stink bug Bottom Photo: Lawrence Abrahamson, State University of New York,

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods Amanda C. Hodges, Ph.D., SPDN Assistant Director, University of Florida Amanda M. Ellis, University of Florida, SPDN Authors

MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods This publication can be used for non-profit, educational use only purposes. Photographers retain copyright to photographs or other images contained in this publication as cited. This material was developed as a core training module for NPDN First Detector Training. Authors and the website should be properly cited. Images or photographs should also be properly cited and credited to the original source. Publication Number: 0008 Publication Date: December 2006 Publication Details