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The Fall Webworm - Prevention and Control

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The Fall Webworm - Prevention and Control

Fall Webworm

USFS

What Trees are Attacked?:

The fall webworm or (Hyphantria cunea) is known to feed late in the season on nearly 100 different species of trees in North America. These caterpillars construct massive silk webs and prefer persimmon, sourwood, pecan, fruit trees and willows. The webs are unsightly in the landscape and generally more numerous when the weather has been warm and wet for extended periods. The insect thrives on sun and moisture. The fall webworm is usually of only minor economic importance as a forest pest.

How are Trees Killed?:

Actually trees are seldom killed by the fall webworm but can be unpleasant to deal with. The caterpillar often covers tree limbs and leaves with unsightly webs in the landscape. This is disturbing to property owners when their trees and ornamentals are heavily defoliated and the presence of the large, unsightly webs can make them aesthetically detracting. Also, infestations of fall webworm is of major concern to the pecan industry and can result in a loss of nut production.

Prevention and Control:

More than 50 species of insect parasitoids and 36 species of predators of the fall webworm are known in the U.S. Still, they are not commercially available. On small trees, nests can be cut out and destroyed - never try to burn these nests as damage to the host may result.
Soap or other insecticides may be applied from mid- to late- summer. Several chemical insecticides and a microbial insecticide, Bacillus thuringiensis can be used to control of this insect. Consult a pest-control specialist.

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