How to identify
Variable-colored caterpillar (green, brown, or pinkish) up to 1.5 inches long with stripes and tiny spines, found tunneling into corn ear tips. The adult is a nondescript tan moth — the same species is called the tomato fruitworm and cotton bollworm depending on which crop it's ruining.
Damage signs
Larvae chew into the silk channel and feed on kernels at the ear tip, leaving frass and damaged kernels that invite mold. On tomatoes they bore into fruit; on beans and lettuce they chew buds and leaves.
Plants it attacks
Corn, tomato, cotton, beans, lettuce, peppers
Non-chemical controls
- Apply a drop of mineral oil or a pinch of sand to corn silks after pollination — it smothers or abrades larvae entering the ear.
- Plant corn varieties with tight husks, which physically block larvae from reaching the kernels.
- Release Trichogramma parasitic wasps timed to moth egg-laying for biological control.
- Handpick larvae from ear tips at harvest — the damage is usually limited to the tip, so just snap it off and eat the rest.
- Till soil in fall to destroy overwintering pupae.
- Use pheromone traps to monitor moth flights and time your controls.
Nerdy fact: The corn earworm, tomato fruitworm, and cotton bollworm are all the same insect with three different PR teams. It causes over $2 billion in damage a year in the US alone — the most expensive caterpillar in American agriculture.