Fall Webworm Attacks Trees

City of Kelowna Press Release

If you’ve noticed web-like wraps appearing in your trees, it’s the work of the fall webworm. Although many people blame the “tent caterpillar”, the webs are actually created by an insect known as fall webworm and, unlike true tent caterpillars, fall webworm rarely causes severe damage.

Fall webworm populations are cyclical, with higher numbers appearing every few years in late summer or fall around the Okanagan. They feed on a wide variety of trees and shrubs, constructing their webs to act as protection against natural parasites and predators. Webworm caterpillars are greenish or yellow with long white hairs. Avoid touching the hairs with bare skin, as they may cause an irritating rash.

Fall webworm is primarily an aesthetic problem, since feeding is usually limited to a few branches and rarely causes any serious defoliation. Given enough time, natural enemies will bring this insect under control.

As a result the City of Kelowna Parks Division does not apply pesticides against fall webworm. Concerned property owners are encouraged to prune out small webs and destroy them. Alternatively the tents can be blasted with water or poked open with a pole to expose the caterpillars to predators.