Moths lay eggs on green silks. The newly hatched larvae chew into the ear tip and feed for 3 - 4 weeks. Full grown larvae leave the plant and burrow into the soil to pupate.
Corn earworms can be found feeding in the whorl but will not cause significant injury. They will feed in the tips of ears, destroying some kernels.
Repeated insecticide applications are needed to significantly reduce infestations because moths lay eggs over an extended period of time. Control attempts cannot be economically justified.