Full-grown caterpillars of the second generation, which develop in mid- to late summer, drop off plants to pupate. In contrast, late-instar tobacco hornworm caterpillars have seven diagonal stripes on their body and their horn is usually red (Figure 2).

Also, full- grown tomato hornworm caterpillars have V-shaped markings on their sides and usually have a black horn. When fully-grown, caterpillars are usually green in color, but dark brown types can also develop. The first small instar is whitish-yellow with five pairs of prolegs used to grip onto plant stems and leaves.

After mating, females lay their small eggs, which often are undetected, on the upper and lower surface of tomato leaves and other host plants.Īfter hatching, tomato hornworms undergo five larval or instar stages in three to four weeks. Both species are mottled gray-brown moths with four to five-inch wingspans. The adult moths emerge in mid- to late spring. There are usually two generations of hornworms produced each summer. These pests also feed on eggplant, pepper, potato, and on weeds, such as horsenettle, jimsonweed, and nightshade.įigure 1 Tobacco hornworm with its prominent reddish-colored 'horn' on a tomato stem. Hornworms also chew holes in green tomato fruit, especially during dry weather.

Both types of hornworm caterpillars devour leaves and can completely defoliate tomato plants if left unchecked. However, the tomato hornworm ( Manduca quinquemaculata) and the tobacco hornworm ( Manduca sexta) are often the most noticeable, measuring up to four inches-long with a prominent 'horn' on the last segment of their body (Figure 1). Several types of caterpillars can cause damage to tomato plants in Missouri.

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