Tomato Fruitworms
Tomato fruitworm, Helicoverpa (Heliothis) zea (Boddie); Tobacco budworm, Heliothis virescens (Fabricius), Noctuidae, LEPIDOPTERA


DESCRIPTION

Adult - The tomato fruitworm moth is usually light yellowish-olive with a single dark spot near the center of each forewing. Tobacco budworm moths are light olive to brownish-olive with a wingspan of 3.2 to 3.8 cm. Each forewing bears 3 slanted dark olive or brown bands. Hind wings are white with white borders.

Egg - Eggs of both species are similar in appearance. They are almost spherical with a flattened base, about 0.6 mm in diameter, and white or cream color. They develop a reddish-brown band just prior to hatch.

Larva - Both species are similar in appearance. Newly emerged larvae are yellowish-white with a brown head. Color varies from greenish-yellow and reddish-brown or even black with paler stripes running lengthwise on the body. The skin of the tobacco hornworm has microscopic spines which are longer and closer to the setae than those of the tomato fruitworm.

Pupa - Pupae of both species are typical for this family (Noctuidae). Shiny and reddish-brown at first, they become dark brown before adult emergence.


BIOLOGY

Distribution - Tomato fruitworm occurs throughout the Western Hemisphere extending as far north as Canada and as far south as Argentina. The tobacco budworm has a similar distribution but is more abundant in warmer regions, whereas the tomato fruitworm is more abundant in cooler regions. In North Carolina, fruitworms occur throughout the state but are generally more severe in the southern Coastal Plain.

Host Plants - The tomato fruitworm feeds on at least 16 cultivated plants. Corn is the most important host of the tomato fruitworm. The tobacco budworm does not infest corn, but both species are common on cotton and soybeans. Cotton, soybeans, tomatoes and tobacco are the only cultivated crop hosts of the tobacco budworm in North Carolina. Wild hosts include deergrass and toadflax.

Damage - Fruitworms, primarily the tomato fruitworm, feed on tomato leaves and fruit. Distorted leaves often result from feeding upon the tips of the leaves in the developing bud. Both species may also bore in stalks or midribs.

Life History - Fruitworms overwinter as pupae in the top 4 cm of soil. Tomato fruitworm adults emerge from early May to early June. Females generally emerge earlier than males. Tobacco budworm adults emerge in North Carolina from late April to mid-May. Eggs are deposited on the leaves or buds of tomato plants. After hatching, larvae may first feed on leaves and then move to buds or fruit. Tomato fruitworm larvae have 5 to 6 instars with the development period varying from 21 to 25 days. Tobacco budworm development is similar. Pupation occurs in the soil. Tomato fruitworm pupae enter diapause in August in North Carolina and tobacco budworms begin diapause in September. Both species have 4 generations per year in North Carolina.


CONTROL

The wasp parasite Campoletis sonorensis kills small tobacco budworms and another wasp parasite, Cardiochiles nigriceps, kills budworms in the prepupal stage. Predators include several Polistes paper wasps. Several diseases including the microsporidian Nosema heliothidis Lutz and Splendor also reduce budworm populations. For specific chemical control recommendations, see the current North Carolina Agricultural Chemicals Manual.

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