Two black spots are present on the second segment, and there are five pairs of prolegs. Larvae fall and curl up when disturbed. Small larvae web the leaf underside. Beet armyworm is chiefly a pest of late-planted seedling soybeans. Small larvae skeletonize the lower leaves.
Large larvae feed over the whole plant.
Severely damaged plants are very ragged in appearance. Larvae are yellow, oval, soft-bodied, grublike insects with darker, branched spines. Adults and larvae feed on the underside of leaves and eat the softer leaf tissues. Damaged leaves appear netlike. Mexican bean beetles attack soybeans throughout the season, but most damage occurs in August and September.