Corn earworm

📖Overview

Helicoverpa zea is a moth in the family Noctuidae. The species is highly polyphagous: its larvae (caterpillars) attack a wide variety of crop plants including corn, cotton, tomatoes, soybean and many vegetables and ornamentals. It has multiple generations per year in warm regions and is an economically important pest because larval feeding damages fruit, ears and bolls. Adults are strong fliers, nocturnal and attracted to lights and flowers for nectar. Population size and number of generations vary with latitude and climate.

🔍How to identify a corn earworm

Adults have a wingspan of roughly 30-45 mm. Forewings are variable: usually tan to brown with darker markings and a small dark spot near the middle; hindwings are lighter, often pale with a darker margin. Larvae are the damaging stage and are highly variable in color — green, brown, pink or nearly black — often with lengthwise stripes and skin covered in tiny spines. Mature caterpillars reach about 30-40 mm. Eggs are small, spherical and pale when laid, darkening before hatching.

1. Look for variable-colored caterpillars (green, brown, pink) up to 30-40 mm feeding in corn ears or on fruit.
2. Adults have a 30-45 mm wingspan with tan to brown forewings and a small dark spot near the middle.
3. Damage in corn: partially eaten kernels at the ear tip or inside the husk where larvae entered via the silk.
4. Eggs are small and laid singly on silks, leaves or fruit; finding eggs on silks often predicts ear infestation.

Lookalikes

↻Life cycle

1. 🥚

   Egg

   Small spherical eggs laid singly or in small groups on leaves, silks, fruit or flowers; hatch in a few days depending on temperature.

2. 🐛

   Larva (caterpillar)

   The feeding stage; larvae pass through several instars and vary in color. They bore into corn ears or feed on fruit and bolls, causing the economic damage associated with the species.

3. 🫛

   Pupa

   Larvae pupate in the soil in a chamber a few centimeters deep; the pupal stage lasts one to several weeks depending on temperature and generation.

4. 🦋

   Adult (moth)

   Nocturnal, nectar-feeding moths. Adults mate and females lay eggs on suitable host plants to begin the next generation.

🍃Diet and predators

🌱Effect on plants and gardens

Larvae feed directly on reproductive parts of plants: corn ears, tomato fruit, cotton bolls, soybean pods and many vegetables and flowers, causing yield loss and market damage.

How to get rid of corn earworms

Use integrated pest management: monitor adults with pheromone traps and inspect silks and fruit for eggs and young larvae; remove and destroy damaged fruit and ears; in sweet corn, a few drops of mineral oil (optionally with Bt) applied to the silk tip after pollination can protect small plantings; time Bt or other approved sprays to target young larvae before they enter ears or fruit, following label directions; encourage natural enemies; and use early planting and resistant or Bt hybrids where available.

📍Where and when to find it

Look for eggs and small larvae on corn silks, on the outside of tomato fruit, in open bolls of cotton, and on leaves and flowers of host plants; pupae are in the soil near host plants.

✨Fun facts

• Corn earworm larvae are called 'earworms' because they commonly feed inside the tips of corn ears where they are protected.
• Because the larvae feed on many kinds of crops, they are among the most important generalist agricultural pests in the Americas.
• Female moths can lay hundreds of eggs over their lifetime, contributing to rapid population growth when conditions are favorable.

?Frequently asked questions

📷Photos of the corn earworm