Cankerworm, a caterpillar that destroys tree leaves. The caterpillars, or loopers, of two species of moths are given this name. They also are called measuring worms or inchworms. The females of both species are wingless. The moths of one species hatch in the spring and those of the other in the fall or early winter. The caterpillars of the spring species have two pairs of hind legs, and those of the fall species have three. Both species lay their eggs on the trees.
The caterpillars feed on soft parts of the leaves. They will often destroy the foliage of an entire orchard in a few days. One of the best means of controlling these pests is to place a band of some sticky substance around the trunks of the trees early in the spring to trap the females as they crawl up the tree to lay eggs. Spraying with insecticide is effective against the caterpillars.
The moth of the fall cankerworm is Alsophila pometaria; of the spring cankerworm, Paleacrita vernata. Both belong to the family Geometridae, order Lepidoptera.Cankerworms can destroy the foliage of an orchard in a few days.