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Symptoms of Insect Damage |
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Type |
Plant Part |
Portion |
Damage |
Pest |
Order |
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Chewing |
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Leaf |
Whole |
Entire leaf except mid-vein |
Caterpillars, cankerworms, webworms, etc. |
Lepidoptera |
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Rolled, often tied together with silken threads. |
Moth leafrollers, leaftiers. |
Lepidoptera |
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Decaying vegetation. |
Millipedes, centipedes, sowbugs and pillbugs. |
Diplopoda, Chilopoda, Crustacea |
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Distinct portion missing. |
Margin notches. |
Adult vine weevil, etc. |
Coleoptera |
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Margin circular holes. |
Leaf cutter bees. |
Hymenoptera |
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Random small holes |
Beetles (chafers, weevils, etc.), grasshoppers. |
Coleoptera, Orthoptera |
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Irregular margin cuts. |
Beetles (weevils, etc.) |
Coleoptera |
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Surface |
Eaten (skeletonized). |
Slugs (look for slime trails), beetle larvae, pearslugs (pear sawfly larvae), elm leaf beetles, thrips, etc. |
Mollusca, Coleoptera, Hymenoptera, Thysanoptera |
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Internal |
Mined |
Boxwood, holly, birch, elm leaf miners. |
Lepidoptera |
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Leaf stalk |
Internal |
Bores into stalk. |
Larvae of moth or sawfly such as maple petiole borer. |
Lepidoptera, Hymenoptera |
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Twig |
Bark |
Eats around twig circumference. |
Vine weevil and twig girdling beetle. |
Coleoptera |
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Trunk or branch |
Cambium, xylum or solid wood. |
Bores into wood forming galleries and holes. |
Mountain pine beetle, European elm bark beetle, raspberry crown borer, Sequoia pitch moth, etc.. |
Coleoptera, Lepidoptera |
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Root |
Rootlets |
Chews off various rootlets. |
Sod webworm, Japanese beetle larvae, root weevil larvae. |
Lepidoptera, Coleoptera |
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Sucking |
Leaf |
Whole |
Spotting or stippling from insect toxins and enzymes. |
Aphids, leafhoppers and plant bugs are usual pest. |
Homoptera, Hemiptera |
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Curling or puckering due to severe toxin reaction. |
Severe aphid infestation. |
Homoptera |
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Margins, veins or whole leaf. |
Distorted new growth with leaf margins rolling, veins swelling or whole leaf distorted. |
Eriopyhid mites. |
Acarina |
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Surface |
Uniform stippling, flecking or chlorotic pattern. With spider mites there is fine webbing under leaf with eggs and frass. |
Adelgids on spruce needles or bronzing by lace bugs. Spider mites also cause damage. |
Homoptera, Hemiptera, Acarina |
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Random stippling. |
Leafhoppers, mites. |
Homoptera, Acarina |
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Leaf and stem. |
Whole |
Distortion associated with off-color foliage. |
Rose aphid, black cherry aphid, leaf curl plum aphid. |
Homoptera |
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Tissue |
Galls or swellings. |
Aphids, wasps, midges, mossyrose gall wasp, poplar petiole gall midge, azalea leaf gall. |
Homoptera, Hymenoptera, Diptera |
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Twigs |
Whole |
Splitting due to egg laying. |
Tree hoppers and cicadas. |
Homoptera |
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Root, stem, branch |
Whole or section. |
Poor color, reduced growth or dieback. |
Scales, mealybugs, pine needle scales. |
Homoptera |
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Whole plant |
Most parts. |
Reduced growth and chlorosis due to systemic toxin reaction. |
Psyllids, scale or mealy bugs. |
Homoptera |
