They make holes in the leaves and are damaging only under very high populations or in combination with other defoliators. They are present throughout most of the growing season. Light green in color with several thin light lines running the length of the body. The body of this caterpillar is largest at the rear and tapering to the head. There are three pairs of prolegs.
Loopers eat large holes in the leaves and, under high populations, can strip an entire field.
Economic infestations of this pest seldom occur before late August or early September. This pest usually occurs in fields that have been previously sprayed. Greenish, brown, or almost black caterpillars with a broad lighter band down each side. Head is prominent and usually yellow or orange. Caterpillars have five pairs of prolegs with the last pair having the appearance of a forked tail.