Oklahoma Master Gardeners Eric J. Rebek Dept. of Entomology and Plant Pathology Who Dunnit? Diagnosing Plant Damage Due to Insects

Oklahoma Master Gardeners

Eric J. RebekDept. of

Entomology and Plant Pathology

Who Dunnit? Diagnosing Plant Damage Due to

Insects

Oklahoma State University


Where Arthropods Attack Plants

Signs and Symptoms of Insect Damage



Signs vs. Symptoms

• Symptoms– Discoloration or

distortion of leaves, blossoms or twigs

– Chewing damage– Cracked bark– Dieback of plant

parts

• Signs– Waste products;

honeydew, frass (excrement)

– Webbing– Cast skin (exuvium)– Insects themselves



Eggs

Frass InsectsWebbing

Signs, Signs, Everywhere Are Signs…



Disease Insect

Look for Signs of Causal Agent



Look for Signs of Causal Agent



Symptoms: Discoloration Due to

Insect Feeding• Small, spotty

patches of discolored leaf tissue

• Can often coalesce into larger blotches



What Caused This Leaf Discoloration?



What Caused This Leaf Discoloration?



What Caused This?



What Caused This?



What Caused This?



What Caused This?



What Caused This?





What Caused These?



What Caused This?

Types of Feeding Damage



Sucking Damage

Sucking Damage



Distorted Growth

DiscolorationWilting



Who Sucks?

• Aphids• Scales• Mealybugs• Thrips• Plant bugs



Piercing-Sucking Mouthparts

leg 1

leg 2

leg 3

antennae

eyes



Chewing Damage

Chewing Damage



Internal External



Who Chews?

• Caterpillars• Beetles

– larvae & adults

• Grasshoppers and crickets– nymphs &

adults

• Sawflies

Caterpillars vs. Sawflies

1234

5

1

2 34 5

6

7

8

• ≤ 5 pr. prolegs• crochets present

• ≥ 6 pr. prolegs• crochets absent




Chewing Mouthparts



Other Types of Insect Injury

Leaf miner

Apple maggot

Gall insect

Wood borer



Other Types of Insect Injury

Root feeders

Leaf cutters

Oviposition damage



What kind of damage is this?













Insect Friend or Foe?



The Good & The Bad



Beneficial Insects

Predators

Weed feedersParasitoids

Pollinators Decomposers



Is This a Pest?



Where Is the Pest?



Stink Bugs



Are These Pests?



Lacewing larva

Are These Pests?

Ladybug larva

NO!



Large grasping

jaws



Is This a Pest?



Is This a Pest?





Is This a Pest?





What happened to this insect?



Is This a Pest?



Is This a Pest?



Is This a Pest?



• Before making recommendations:– Find out “WHY” your client gardens– Create an atmosphere of enjoyment

and learning– Ask lots of questions about the

situation (DETAILS)– Try not to treat insect management as

a ‘CHORE’ but as a necessary challenge

Master Gardener Diplomacy:

(Insect Management)

Documents

Oklahoma Master Gardeners Eric J. Rebek Dept. of Entomology and Plant Pathology Who Dunnit? Diagnosing Plant Damage Due to Insects