Corn earworms are caterpillars of the moth Helicoverpa zea. The same insect is called tomato fruitworm or cotton bollworm when it feeds on other crops. The caterpillar may be green, tan, pink, brown, or almost black, usually with lengthwise stripes.
Adult moths are attracted to fresh corn silk and lay eggs nearby. A caterpillar moves down the silk channel and feeds on kernels, usually near the tip of an ear. Once inside, it is protected by the husk.
Reduce the damage
- If earworms are a repeated local problem, choose an early-maturing sweet-corn variety. Earlier crops often escape the largest late-season moth flights.
- Varieties whose husks close tightly over the ear tip can be less vulnerable.
- Watch the silks and ear tips for eggs or feeding, especially while the corn is silking.
- At harvest, ask an adult to peel the husk, remove the caterpillar, and cut off the damaged tip. The unaffected part of the ear can be cooked and eaten.
- Do not compost a living caterpillar; it may finish developing. Dispose of it or drop it into soapy water.
Older recommendations use mineral oil, eyedroppers, powdered pepper, or repeated sprays on every ear. Exact timing and dose matter, and oil applied too early can interfere with pollination. This children’s guide does not recommend a homemade mixture. Ask a local extension service about current controls if damage is consistently serious.
Fascinating Facts!
- Corn earworms are not worms; they are moth caterpillars.
- A caterpillar may eat other earworms it meets, so only one large larva is often found in an ear.
- The moth cannot survive very cold winters in much of Canada and the northern United States. Each year, moths can arrive from warmer regions on weather systems.
- The insect also feeds on tomatoes, peppers, beans, and other crops.
- Cutting away a damaged ear tip is often the simplest solution for a home gardener.