Fall Webworm (Hyphantria cunea)
U.S. Department of Agriculture, Forest Service. 1979. A guide to common insects and diseases of forest trees in the northeastern United States. Northeast. Area State and Private Forestry, Forest Insect and Disease Management., Broomall, PA. p. 123, illus.(USDA Forest Service, Northeast Area State and Private Forestry Publication. NA-FR-4)
In autumn, fall webworm colonies attack ash, black walnut, hickory, oak, and other hardwoods, enveloping the ends of branches with large, unsightly webs. Because defoliation comes late in the growing season, fall webworm damage usually is considered serious only where esthetic values are important. Its host list includes more than 100 tree species.
The adult moths appear from May to July, and soon deposit hair-covered masses of several hundred eggs, usually on the undersides of leaves. The moths vary in color from white with dark spots on the wings to pure white. The larvae, which are covered with long, gray hairs, are pale yellow, brown or green, with a broad, dusky stripe down each side. They usually do not entirely consume the leaves, but skeletonize them to such an extent that the leaves curl, dry up, and eventually die. The larvae feed gregariously until the last instar. After feeding, the larvae drop to the ground where they pupate in the duff or the upper surface of the soil. There are one or two generations per year, depending on location.