Moths lay eggs on green silks. The newly hatched larvae chew into the ear tip and feed for3 - 4 weeks. Full grown larvae leave the plant and burrow into the soil to pupate.
Corn earworm can be a very serious popcorn pest by eating or damaging kernels at the ear tip. Corn earworm damage to kernels can bring a lower selling price. Earworms only lay eggs on fresh silks.
If insecticides are used for earworm control, they should only be applied after tassel emergence and before the silks dry. Pheromone traps can be used to monitor earworm activity and predict severity of egg laying.
| Insecticide | Rate per Acre | Notes |
| Ambush 2 E | 6.4 - 12.8 fl oz | Apply prior to brown silk |
| Asana XL | 5.8 to 9.6 fl oz | 1 day PHI |
| Capture 2EC | 2.1 to 6.4 fl oz | 30 day PHI |
| Bt products | See labels for rates | |
| Lannate 90 WSP | 1/4 to 1/2 lbs | 21 day PHI |
| Lorsban 4 E | 1 to 2 pints | 35 day PHI |
| Mustang Max | 1.76 to 4.0 fl oz | 30 day grain, 60 day silage PHI |
| Pounce 3.2 EC | 4 to 8 fl oz | Apply prior to brown silk |
| Sevin 80 S | 1-1/4 to 2-1/2 lbs | 14 day PHI |
| Tracer 4SC | 2 to 3 fl oz | 28 day PHI |
| Warrior T | 1.92 to 3.20 fl oz | 21 day PHI |