Lepidoptera: Lymantriidae

Hosts: Prefers ornamental species of poplar, but will feed on all species of poplar and willow, and occasionally on other hardwood species

Evidence: When fully grown in June, larvae feed openly and consume whole leaves, except the major veins. The distinctive larva has a dark-colored body with a row of large, squarish white or pale yellow spots down its back, and a narrow, broken white line down each side. Each body segment also has reddish tubercles bearing long, brownish hairs. Look for shiny black pupae, with gold and white hairs, that occur in loosely woven silk cocoons spun in leaves or on twigs or other objects. Adults have white wings with a satiny sheen and they are active flyers, both day and night, from late June to early August.

Life Cycle: There is one generation per year. Tiny second instar larvae overwinter in silken, cocoon-like bags which are covered with bits of bark or moss and attached to trunks or branches of host trees. They emerge out of hibernation to feed after the new leaves have formed in the spring, and continue to feed and grow until late June. Mature larvae pupate in loosely woven silk cocoons attached to leaves, rocks, branches, fenceposts, or other solid objects. Adults emerge 10-14 days later. In July, mated females lay 100-400 eggs in oval clusters on leaves, branches, or trunks. The eggs are covered with a foamy, white secretion and hatch after about two weeks. Young larvae move to the leaves and feed briefly on the leaf surface. After molting and then feeding again for roughly a week, the larvae seek out hibernation sites in bark crevices and spin individual winter cocoons.

Management: Most defoliated trees will refoliate successfully by midsummer. Although defoliation may cause the death of a few branches, it rarely kills healthy trees. Occasionally, fairly extensive (>5000 acres) defoliation of woodland aspen has occurred, especially in Maine. This defoliation seldom occurs for more than three successive years, and losses have been minimal. Satin moth eggs, larvae, pupae, and adults have a number of natural enemies, including insect parasites, insect and vertebrate predators, fungi, bacteria, and viruses. Late frosts in spring can kill off early larvae directly or indirectly, by ruining their food supply. Infestations are usually short lived, and artificial control is generally not needed. Larvae can be destroyed by spraying an insecticide on the foliage in the spring when leaves begin to open.