How to Stop Tomato and Tobacco Hornworms

Hornworms are large (up to 4 inches) green caterpillars on tomatoes, peppers, eggplants, and potatoes. Tomato hornworms (black horn, white V-marks) are northern; tobacco hornworms (red horn, white stripes) are southern. They blend with foliage, often unnoticed until heavy defoliation occurs. Adults are large, thick-bodied moths (hummingbird/sphinx/hawk moths) that hover at dusk.

Cultural control: Hand-pick large larvae (use gloves if squeamish). Destroy them.

Biological control: Ladybugs and lacewings eat eggs and young larvae. Braconid wasps lay eggs in hornworms; the white cocoons on the caterpillar's back mean it's parasitized. Leave these alone — emerging wasps will attack more hornworms.

Insecticidal Sprays

Bt (Bacillus thuringiensis) kills young larvae but not mature ones. Spinosad (organic) works on young larvae. Carbaryl and permethrin are chemical options.