Tobacco Hornworm

Millie Davenport,
Home & Garden Information Center

Tobacco Hornworm
Tobacco Hornworm

At this time of year, many gardeners find that their tomato plants have been stripped of foliage. With a closer look, it may be determined that the tobacco hornworm is to blame. The tobacco hornworm caterpillar is light green in color with seven white diagonal stripes down each side of its body and a distinctive red “horn” on its posterior. The tobacco hornworm will reach up to 4½ inches long. It feeds on the foliage of tomato plants but will also feed on other plants in the nightshade family, such as Irish potato, eggplant and peppers. If a heavy infestation develops, the caterpillars may also feed on the surface of developing tomato fruit, leaving large open scars. Fortunately, the tobacco hornworm has many natural enemies, such as the braconid wasp. The braconid wasp parasitizes the hornworm by inserting eggs into its body. The developing larvae then feed on the hornworm. When the larvae pupate, they spin a small white cocoon on the outside of the hornworm’s body. The clusters of small white cocoons are found on the outside of a parasitized hornworm, making the caterpillar more visible in the tomato foliage.

For more information see HGIC 2218, Tomato Insect Pests.

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