Oklahoma Master Gardeners

Eric J. RebekDept. of

Entomology and Plant Pathology

Who Dunnit? Diagnosing Plant Damage Due to

Insects

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Where Arthropods Attack Plants

Signs and Symptoms of Insect Damage

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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

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Eggs

Frass InsectsWebbing

Signs, Signs, Everywhere Are Signs…

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Disease Insect

Look for Signs of Causal Agent

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Look for Signs of Causal Agent

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Symptoms: Discoloration Due to

Insect Feeding• Small, spotty

patches of discolored leaf tissue

• Can often coalesce into larger blotches

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What Caused This Leaf Discoloration?

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What Caused This Leaf Discoloration?

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What Caused This?

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What Caused This?

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What Caused This?

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What Caused This?

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What Caused This?

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What Caused These?

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What Caused This?

Types of Feeding Damage

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Sucking Damage

Sucking Damage

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Distorted Growth

DiscolorationWilting

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Who Sucks?

• Aphids• Scales• Mealybugs• Thrips• Plant bugs

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Piercing-Sucking Mouthparts

leg 1

leg 2

leg 3

antennae

eyes

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Chewing Damage

Chewing Damage

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Internal External

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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

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Chewing Mouthparts

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Other Types of Insect Injury

Leaf miner

Apple maggot

Gall insect

Wood borer

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Other Types of Insect Injury

Root feeders

Leaf cutters

Oviposition damage

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What kind of damage is this?

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What kind of damage is this?

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What kind of damage is this?

What kind of damage is this?

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What kind of damage is this?

Insect Friend or Foe?

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The Good & The Bad

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Beneficial Insects

Predators

Weed feedersParasitoids

Pollinators Decomposers

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Is This a Pest?

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Where Is the Pest?

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Stink Bugs

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Are These Pests?

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Lacewing larva

Are These Pests?

Ladybug larva

NO!

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Large grasping

jaws

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Is This a Pest?

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Is This a Pest?

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Is This a Pest?

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What happened to this insect?

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Is This a Pest?

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Is This a Pest?

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Is This a Pest?

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• 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)