Adults are often mistaken for hummingbirds due to their large size, rapid wingbeats and quick movements. Adult hornworms are large, heavy-bodied hawkmoths with a wingspan of up to five inches. A large red or black horn-like spine protrudes from the posterior (rear) end of caterpillars, giving rise to the name “hornworm”. Tobacco hornworms and tomato hornworms have seven or eight diagonal white stripes, respectively, on each side of their bodies. However, smaller hornworm larvae, due to their color, tend to blend in with plant leaves and can be difficult to detect. When fully grown, hornworm caterpillars (larvae) can be up to four inches in length and easily seen. These insects can also feed on solanaceous weeds such as horsenettle, jimsonweed and nightshade.Īppearance: You can easily identify hornworms by their blue-green color and large size. Tomato and tobacco hornworms feed only on solanaceous plants (i.e., plants in the nightshade family), most typically tomato and less commonly eggplant, pepper and potato. However, large numbers of larvae can occasionally occur in home gardens, leading to significant damage. These insects do not typically cause significant damage in commercial vegetable fields. sexta) are large, blue-green caterpillars (larvae) with a spine (horn) on the posterior (rear) end. Hornworms with these cocoons should not be included in your counts because they are no longer feeding.Tomato hornworms ( Manduca quinquemaculata) and tobacco hornworms ( M. These are cocoons of a tiny wasp that develops inside the hornworm and kills it. Late in the growing season, many of the hornworms may have small, white, football-shaped objects on their backs. If 5 or more hornworms are found per 50 plants, then a spray should be applied prior to harvest. Hornworms feed in the upper 1/3 of the plant and can be found hanging from the underside of the leaf. Use a minimum of 5 locations per field, more are better, especially for large fields. This should allow time for a “clean-up” spray and the harvest interval to pass before tobacco is cut and taken to the curing structure.Ī list of recommended insecticides can be found in ENT-15, Insecticide Recommendations for Tobacco Beds and Fields.Īn assessment of hornworms can be made by carefully examining groups of 20 plants at randomly selected locations over a field. If this is not practical, then plants should be checked about a week before harvest. Ideally, tobacco should be checked weekly from topping until harvest to determine if hornworm numbers justify treatment. ![]() Hornworm infestations must be handled in the field before housing. There are no registered or effective treatments to control hornworms feeding on tobacco in the curing barn. ![]() Hornworms present when the tobacco was cut will be taken to the barn where they will continue to feed until they complete their development and drop to the barn floor. That leaves plenty of time for late-flying moths to lay eggs that lead to infestations. The residual protection from the application usually lasts for 5 to 7 days. ![]() The long flight period means that infestations can develop even if the crop was sprayed with an insecticide soon after topping. Tobacco hornworm moths fly during much of August and early September, attaching single eggs to the undersides of tobacco leaves in the upper 1/3 of the plant. University of Kentucky College of Agriculture ENTFACT-151: Keeping Hornworms from the Curing Barn | Download PDF by Lee Townsend, Extension EntomologistĪnd Bob Pearce, Extension Tobacco Production Specialist
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