WSU Extension

Hortsense

Common Insects & Mites : Fall webworm
(revision date: 4/30/2013)


Biology
Fall webworm caterpillars feed on the foliage of a variety of trees and shrubs. Conspicuously hairy, they appear rusty tan with a dark, almost black, body color. Some populations have a lighter tan color phase. Large tents of this late-season pest become noticeable in late summer and early fall. Caterpillars are particularly fond of alder, cottonwood, walnut, and apple. They sometimes feed on apple fruit as well as foliage.
Management Options

Non-Chemical Management
  • Prune out and destroy caterpillar tents.
Select non-chemical management options as your first choice!

Chemical Management

Pesticide applications are generally not recommended. If you choose to make an application, make certain that the pesticide applied is registered for the host and effective against the pest. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Images
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Caption: Fall webworm
Photo by: S.J. Collman
Caption: Fall webworm tent on apple
Photo by: R.S. Byther