Fall Webworm is just another insect to plague our trees this season. Unsightly tents are appearing everywhere. The favourite host trees of the Fall Webworm include Walnut, Cherry, Hickory, Crabapple and Birch trees.
Larvae (caterpillars) pass through as many as 11 instars on their way to developing into adults. They create silken tents on the ends of branches. As they occur so late in the growing season, there is usually no need to control fall webworm. Webworms have many natural enemies including birds, predaceous bugs and parasitic wasps. Leaving the webs intact allows populations of their natural enemies to develop.
However, if deemed necessary, the unsightly nests in the lower canopy of the tree can be dislodged with a strong stream of water or with a pesticide such as Bt. (Bacillus thuringiensis). The nests can be removed but this also removes potentially healthy branches with buds for next year’s growth. Pruning can be done at any time of day as these caterpillars stay in the web while feeding.
Call Shady Lane Expert Tree Care if you would like our plant health care team to take care of your Fall Webworm issues.
Reference; A Pocket IPM Scouting Guide for Woody Landscape Plants Diane Brown-Rytlewski