Corn Earworm

Symptoms by part

Causes

• The presence of adult moths laying eggs on fresh corn silks during the silking stage.
• Warm temperatures that accelerate the life cycle of the larvae.
• Lack of natural predators like parasitic wasps or lady beetles in the garden.

Could be confused with

• European Corn Borer · The European corn borer typically tunnels into the stalks and cobs rather than feeding primarily on the silk and ear tips.
• Fall Armyworm · Fall armyworms often feed in large groups and leave behind much more extensive, ragged leaf damage before moving to the ears.

Treatment

1. Handpick the larvae from the ear tips early in the morning when they are most active.
2. Apply a drop of vegetable oil to the silk channel of each ear after the silks have begun to wilt to suffocate young larvae.
3. Apply Bacillus thuringiensis to the silk of each ear once per week until the silks turn brown, follow the label.
4. Apply spinosad to the silk of each ear once per week until the silks turn brown, follow the label.

Without chemicals

• Use fine mesh bags or clothespins to secure the silk channel after pollination to prevent egg laying.
• Plant early maturing varieties to harvest before peak moth populations arrive.
• Till the soil after harvest to expose pupae to birds and cold weather.

Chemical options

• Bacillus thuringiensis, apply to the silk, follow the label.
• Spinosad, apply to the silk, follow the label.

Preventing it

• Rotate your corn crops to different areas of the garden each year.
• Plant flowers like dill, fennel, or yarrow nearby to attract beneficial insects that prey on the larvae.
• Remove and destroy all corn stalks and debris immediately after harvest to disrupt the life cycle.

When to act

Act as soon as you see the first signs of silk feeding or egg laying on the silks. If the infestation is widespread and the majority of the ears are severely damaged, it is best to remove the plants and compost them away from the garden.

Questions people ask

Is corn with earworm damage safe to eat?

Yes, you can simply cut off the damaged tip of the ear and the rest of the corn is perfectly fine to eat.

Why do they only seem to attack the tips?

The larvae hatch on the silks and follow them down into the ear, so the tip is the first and most accessible part they encounter.

Plants it affects

• Maize