The female punctures squares and young bolls to lay eggs. These nipple-like egg punctures are about 1 mm in diameter. Egg-punctured squares flare and fall to the ground where larval development is completed. Caterpillars - These moth larvae have 3 pairs of short legs near the head and 5 pairs of prolegs. Bollworm complex - When fully grown, these larvae are green, reddish, or brown with pale, longitudinal stripes and scattered, black spots.
Early instars are cream colored or yellowish-green with few markings.
Larval instars vary from 1.5 to 44 mm in length and have 5 pairs of prolegs. The contents of squares or bolls may be completely consumed by bollworms. Cotton lint development is reduced and rot organisms may gain entrance into the bolls that are only partially damaged. B.1.b. of this key for description. This caterpillar may bore into stems and bolls like the bollworm, but typically enters the boll at the tip or at the base next to the stem.