If disturbed, moths flit about in a jerky, zig-zag fashion before landing a short distance away. Eggs, deposited singly on the lower blades of grass plants, are tiny, oval, slightly flattened, and have a greenish tinge. Larvae are dirty white with numerous small black spots. The body is sparsely covered with numerous pale hairs. Webworms are very active.
Pupae are dark brown but are enclosed in a thin white, flimsy silken cocoon.
They are near ground level in grass crowns. They start feeding in April and complete their development in early June. They pupate in loosely woven silken cocoons and moths emerge by mid-June. Moths drop their eggs in grassy areas and a new generation of larvae hatch in about 7 days. There is only one generation per year for the corn root webworm.