Female moths lay eggs singly on leaves on the lower half of the plant canopy. The eggs, which are deposited at night, hatch in about 3 to 5 days. At first, young larvae feed on the lower half of the plant. Larger larvae move up the plant, feeding on cotton leaves for about 2 weeks before pupating. Pupation occurs within a thin, silken web on the underside of leaves.
Moths then emerge and mate.
Female moths begin laying eggs, and each lays an average of 600 eggs. Hundreds of moths per acre may be present during a heavy soybean looper outbreak. Loopers are semitropical pests. They can overwinter in the United States only in south Florida and south Texas. Large populations may also migrate from Central and South America and the Caribbean Islands.