Common Name: Tomato and Tobacco hornworms
Scientific Name: Lepidoptera: Manduca sp
Status: A pest of certain vegetable plants
Damaging Stage: Caterpillar

Biology: Hornworms are large, robust moths that have long, narrow front wings. Their bodies are spindle-shaped, pointed at both ends. They have gray and white mottled wings and abdomens lined along each side with five (tomato hornworm) or six (tobacco hornworm) conspicuous, orange-yellow spots.

The large green caterpillars are very distinctive. They are cylindrical and can grow to three inches in length. A large, thick, pointed structure or �horn� protrudes from the upper abdominal end and is responsible for the name 'hornworm'. Seven straight, oblique white lines, edged with black on the upper borders run laterally along the abdomen of the tobacco hornworm. Tomato hornworms have 8 v-shaped marks.

Females lay their eggs singly on leaves. The eggs hatch and the larvae feed for three or four weeks and then burrow into the soil to pupate. The pupae overwinter and the adults emerge in the spring. There are two generations per year.

Injury: Larvae feed on plant leaves and develop through five instars. They feed on foliage, blossoms and green fruits of tomatoes, tobacco and potatoes, eggplants, and peppers. The fifth instar is responsible for the majority of the defoliation that occurs.

Action Threshold: Due to their size, tobacco hornworms can consume large quantities of plant material. However, hornworms are not considered to be pests of commercial crops, probably due to the activities of natural enemies. Control is usually not necessary.

Management: Several management methods are productive. Naturally occurring parasitic wasps provide biological control in most cases. In home gardens, rototilling to destroy the pupae and physical removal of caterpillars is usually more than sufficient. Bt is effective against early instars. Chemical control is also effective.