Tomato hornworms are the larvae of a large sphinx moth that is about the size of a hummingbird. In spring the moth lays eggs on the underside of tomato - and related plants like pepper and eggplant - leaves. Although the hornworms are quite small when they first emerge, they are big eaters (of leaves) and grow up quickly. Usually, you won’t even discover this fellow until it is large-about 2 inches long and fat! They are quite distinctive looking (once you find one); almost handsome with their diagonal white stripes and horns on the rear.
Don’t be afraid of the hornworms. They look more frightening than they are. They don’t bite or sting, just try to look big and ferocious. You can easily handpick to remove them from your plants and just throw them in a bucket of soapy water. (If you can’t stand the thought of touching them, you can cut them in half with garden scissors - but that’s a bit messy.) If you find them when they are younger and smaller, you can use Bt (bacillus thuringiensis) as an effective management technique.
Some gardeners have a different approach to the tomato hornworm. While handpicking a hornworm, look to see if you find little white cocoons attached to its back. If you do see this, that cocoon is a pupating braconid wasp, which is a garden-friend predator. Capture the hornworm and keep it in a container, feeding it tomato leaves. You are creating a nursery for the braconid wasps, which can then be released into your garden! These wasps will help control the hornworm population.
Other natural predators are birds and the larvae of the green lacewing. Plant your gardens in a way to create an inviting habitat for all of these natural predators, and you’ll control this voracious eater of your tomato and pepper leaves. Luckily, hornworms don’t eat the fruits, but they can sure do a job on the leaves!