In the garden: Numerous trees including nut trees and willows
On Crops: Fruit and nut trees
Originally from North America, now distributed worldwide in temperate climates
From midsummer onward, messy webs appear in the tips of branches in over 600 species of hardwood trees. Inside the webs, hairy caterpillars with thin bodies skeletonize the leaves, and the web is enlarged as the colony's need for food increases. Fall webworms are a different species from eastern tent caterpillars, a common "webworm" of early summer that builds neat nests snugged into the crotches of fruit tree branches.
Large trees can tolerate moderate feeding by fall webworms, but infested branches look unattractive as the web enlarges over tattered brown leaves. The webworms feed for four to six weeks, and overwinter as pupae in bark crevices or weedy debris. The adult moths are quite beautiful, being buff beige with a tuft to fine fur on their backs. They fly at night, and are attracted to outdoor lights.
Little can be done to prevent these moths from finding hospitable branches in landscape trees. Because trees lose leaves to fall webworms late in the season, they may be slightly weakened by webworm feeding, but make a full recovery the following season.
Use a long stick with an old toothbrush taped to the end to disturb nests within reach. Poke holes in the web, and then twist the stick to gather up webbing and caterpillars. If a tree has plenty of branches to spare, you can simply lop off the infested branch tips and compost them, caterpillars and all.