Corn Earworm Information, Pictures of Corn Ear Worms

Corn Earworm General Information Corn Earworm Adult Moth Picture Corn Earworm Larvae Picture

The corn earworm is a pest native to all North America except in northern Canada and Alaska. Depending on the location of the insect, it can produce from one to seven generations per year. Corn earworms feed primarily on the stalks of corn, but are also known as the Cotton Bollworm and the Tomato Fruitworm because cotton and tomatoes are one of their primary host plants. When in abundance, they feed on artichoke, asparagus, cabbage, cantaloupe, collards, cowpeas, cucumber, eggplant, lettuce, lima bean, melon, okra, peas, peppers, potato, pumpkins, snap beans, spinach, sweet potato and watermelon.

The adult corn earworm is a moth that is nocturnal and hides in the vegetation during the day. They are yellowish to olive color with a dark spot near the center of their body. They have a wingspan of ½ inch.
The larvae resemble caterpillars and are less than 1/8 inch long. Larvae are yellowish-white with a dark head.
During the second instars, the larvae turn to a yellowish-green color and have dark stripes and a red to brownish head. Just before they pupate into adults, they turn green yellow, reddish or brown with pale stripes and have raised black spots and brown heads. The eggs of the corn earworm are deposited on leaf hairs and corn silk.
Eggs are pale green and turn yellowish and then gray just before hatching.

The corn earworm over winters as pupae in the soil beneath the plant. Adult moths emerge in April to late May and lay eggs on the corn leaves. Females can lay up to 3,000 eggs. After hatching, the larvae feed up to four weeks on the silks of the corn before moving to the end of the ear to feed on the maturing kernels. Later on, the larvae fall to the ground to burrow in the soil and pupate.
After four weeks, adult moths emerge and the cycle begins again.

During feeding, the larvae feed on the foliage and burrow into the stems of the plant, although most of the feeding occurs on the fruit itself. Feeding can cause ragged holes in the foliage. Because the female lays so many eggs, the larvae that hatch are cannibalistic and feed on other larvae. This eventually results in only a couple of larvae remaining on the host plant to continue feeding. In certain states, during late summer, larvae will leave the corn and move to soybean crops and can cause extensive damage.

Common predators of the corn earworm include ladybird beetle, soft-winged flower beetles, green lacewings, minute pirate bugs and big-eyed bugs.

Credits:
Our thanks to Lani Powell for research and writing which made this Corn Earworm information page possible!