Corn Earworm (Helicoverpa zea) moths lay their eggs on fresh corn silks. The caterpillars hatch and feed on the silks before crawling down inside the husk, where they feed on kernels, usually near the tip of the ear. The caterpillars vary considerably in colour and may be green, tan, pink, brown or nearly black, usually with stripes running along the body. Because they are protected inside the husk, gardeners often don't discover them until they peel the ear. In northern regions, Corn Earworm usually arrives as migrating moths later in the summer rather than successfully overwintering locally.

How to Fix It
Plant early: Early-maturing corn can escape much of the later-season Corn Earworm pressure.
Check the silks: Watch newly silking corn closely, since this is where the moth lays its eggs.
Remove damaged tips: If damage is confined to the very tip and the remainder of the ear is sound, cut away the damaged portion along with the caterpillar and frass.
Encourage beneficial insects: Parasitic wasps, predatory bugs and other natural enemies attack Corn Earworm eggs and young larvae.
Bt: Bacillus thuringiensis var. kurstaki can kill young caterpillars, but timing is critical because it becomes much less useful once the caterpillar has entered the ear.
Choose resistant varieties: Some sweet-corn hybrids have greater resistance to Corn Earworm feeding.