Forest Pests: Insects, Diseases & Other Damage Agents

Forest tent caterpillar is an early-season defoliator of several hardwood species. In its northern range, where it feeds on quaking aspen and sugar maple, tree mortality is generally not extensive. However, growth loss in aspen may be considerable, and quantity and quality of sugar maple sap may be reduced. In its southern range, where it feeds on several species of gum and oak, heavy defoliation can produce substantial top kill and mortality of water tupelo and blackgum. In addition to defoliation, migrating caterpillars can be a nuisance to recreationists.

Larvae emerge in the spring and begin feeding immediately, sometimes utilizing expanding buds until foliage is available. The larvae do not form tents, but construct open silken mats on tree branches or trunks, where they congregate to rest and molt. The caterpillar matures in about 5 weeks, at which time it measures 2 to 2½ inches in length. The head is light blue with small, irregular black spots. Each body segment has a footprint-shaped white spot along the back. The sides of the body are pale blue-gray, bounded by a narrow orange stripe on the top and a white stripe below. The eggs, laid in mid-summer, are deposited in bands around small twigs on host trees. These bands are covered with a smooth, black, shiny substance. This pest has one generation per year.

Adult(s); egg mass and adult Photo by Scott Tunnock, USDA Forest Service	Egg(s); egg masses with hatch occurring Photo by James Solomon, USDA Forest Service
Larva(e); Photo by Gerald J. Lenhard, Louisiana State University

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