NC State Extension Publications

Description and Biology

Skip to Description and Biology

As the field crops dry out, corn earworm moths, Helicoverpa zea, lay their eggs on just about anything that is green. It is also known as the tomato fruitworm, the sorghum headworm, the vetchworm, and cotton bollworm. The corn earworm is the second most damaging pest in the United States and is sometimes highly damaging to ornamental crops, especially in middle to late summer when field crops and weeds are drying up, and the only succulent plants left are ornamentals. Corn earworm moths are medium sized and tan to yellowish-brown with darker spots. Forewings of males are usually light yellowish-olive; those of the female are yellowish-brown to pinkish-brown. Each forewing has a dark spot near the center. The moths are active at night, but sometimes fly during the day as well. Females do not lay eggs in masses, but seem to fly from plant to plant laying an egg or two on each. Females can lay 400 to 3,000 whitish-yellow eggs each. Eggs darken and hatch in a few days, and the tiny caterpillars feed on buds, flowers, leaves and fruit. Caterpillars eventually grow to 1 ¾ inches long. When fully grown, this moderately hairy larva is pale-striped, black-spotted and predominantly yellowish-green, brown or reddish-brown with a tan to orange head. When disturbed, it curls up tightly, remaining motionless for a few seconds. Development takes two to three weeks at which time the caterpillars burrow into the soil to pupate. We have at least four generations per year, and corn earworms become most abundant in late summer. The last generation overwinters as pupae more than two inches under ground.

Corn earworm moth

Corn earworm moths sip nectar from flowers.

Corn earworm moths lay 400 to 3,000 eggs each.

Corn earworm moths lay 400 to 3,000 eggs each.

Corn earworm

Corn earworms are typical caterpillars.

Corn earworms usually pupate under ground.

Corn earworms usually pupate under ground.

Host Plants

Skip to Host Plants

The corn earworm infests over 100 plants, but corn is the preferred host. In the South it occurs on at least 17 cultivated plants: alfalfa, bean, carnation, chrysanthemum, corn, cotton, geranium, gladiolus, nasturtium, okra, peanut, pea, rose, salvia, snapdragon, sorghum, soybean, strawberry, sunflower, sweet pepper, sweet potato, tobacco, tomato and zinnia. The earworm is also found on wild hosts such as toadflax, deergrass, common mallow, crown vetch, fall panicum, hemp, horsenettle, lambsquarters, lupine, morningglory, pigweed, prickly sida, purslane, ragweed, and velvetleaf,

Corn earworms feed

Corn earworms feed on a variety of host plants.

Corn earworms feed on a v

Corn earworms feed on a variety of host plants.

Corn earworms feed on a variety of ho

Corn earworms feed on a variety of host plants.

Corn earworms feed on a v

Corn earworms feed on a variety of host plants.

Residential Recommendations

Skip to Residential Recommendations

In hobby greenhouses, damage by corn earworms in a greenhouse can be reduced by adequate screening of window and open areas, as well as proper sealing of door edges. Releasing natural enemies (e.g., Trichogramma wasps and predatory insects) in a residential greenhouse may help control corn earworm if vents cannot be screened. Because the corn earworm feeds on hundreds of kinds of plants, it has not developed resistance to most of the insecticides labeled for home landscape use found in big box stores and garden centers. However, corn earworms have developed resistance to the Bacillus thuringiensis Cry1Ab toxin that has been genetically engineered into some field corn cultivars.

References

Skip to References

For assistance with a specific problem, contact your local Cooperative Extension Center.

This Factsheet has not been peer reviewed.

Author

Professor Emeritus
Entomology

Publication date: May 30, 2016
Revised: Sept. 12, 2019

North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status or disability. In addition, the two Universities welcome all persons without regard to sexual orientation.