Females have white wings with dark markings and a tan to buff colored body. Females are heavy bodied and do not fly. The eggs are round, black to brown in color, and deposited in masses of 100 to 600 eggs in July and August. The masses are covered with a dense mat of tan or buff colored hairs from the females body. The young caterpillars also spin silken threads and hang down from the tree branches.
Wind often breaks the threads and carries the caterpillars to nearby trees and shrubs.
Long range dispersal is aided by man - egg masses or pupae may be inadvertently carried on vehicles, outdoor furniture, plants and the like. Each time the larva grows it sheds its skin and a new larger skin forms. The larval stage lasts for about 7 weeks. In June and early July full-grown larvae may leave the host plant and seek out protected places to form the pupa or resting stage. At this time, the large caterpillars may be seen crawling across walkways or roads, or up the side of a house.