Saddled Prominent (Heterocampa guttivitta)
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)
The saddled prominent prefers sugar maple, yellow birch, paper birch, and beech, but also feeds on other tree species such as oak, aspen, and apple. Young caterpillars skeletonize the leaves, but as the caterpillars mature they consume entire leaves except for a few principal veins. Two or three successive years of severe defoliation may cause significant tree mortality in yellow birch. During droughts or on poor sites, trees of other species may die, and yields of syrup and sugar from sugar maples may be reduced.
The brownish gray moths emerge in late May and early June. The moths--which have a wingspan of about 2 inches--have indistinct and variable crossmarkings on the forewings. Each female moth lays up to 500 pale-green eggs, depositing them singly on the undersides of leaves. Dark-green caterpillars emerge from the eggs in 8 to 14 days. As the caterpillars grow larger, their bodies become light green with reddish to purple saddle-like markings in the middle of the back. When fully grown, caterpillars are about 1½ inches long. Pupae are a glistening dark brown, about ¾ of an inch long, and usually enclosed in a loose silken cocoon in the leaf mold of the forest floor. Pupation occurs in late July and August. The insect produces one generation per year.