Cankerworm, common name for several destructive caterpillars in the measuringworm family, especially the spring cankerworm and the fall cankerworm. Cankerworms are found in the United States from Maine to Texas. The male moth of both species has silky wings; the female is wingless. The females crawl up the trunks of fruit or shade trees to lay their eggs, and the caterpillars, which hatch about the time the tree comes into leaf, often skeletonize the leaves of an entire orchard in a few days. The common name of these two species is derived from the season in which the female lays eggs.
Scientific classification: Cankerworms belong to the family Geometridae. The spring cankerworm is classified as Paleacrita vernata, the fall cankerworm as Alsophila pometaria.