One of the most loathsome garden pests, the tomato hornworm, is just as nasty as he looks. Despite its name, the “hornworm” isn’t a worm at all. This garden pest is actually a caterpillar, the larvae of the hawk moth.
Tomato hornworms are not only destructive, they’re huge! They’ll certainly be the biggest caterpillars in your garden, averaging 4 inches long when fully grown. You can also recognize them by their green color (the same color as tomato leaves, interestingly enough) with white V-shaped markings on its back and a black horn-like appendage protruding from its back end.
Tomato hornworm damage is obvious. Look for large bites missing from leaves and stems of tomatoes, as well as pepper plants and eggplants. Due to their natural camouflage, you may not see the predator, but you will see black droppings on the leaves below the damage. This calling card lets you know it really is the tomato hornworm you’re dealing with. Since they eat so voraciously, take action as soon as you notice damage. If left alone, tomato hornworms can defoliate an entire plant in only a matter of days. But if you remove them soon enough, plants generally recover.
One way to remove tomato hornworms is by hand. Look for them, pick from from the plant and then squish them or drop them into a tin of soapy water. They feed at night, so if you do not see them in the daytime, go out looking for them with a flashlight in the evening.
If an infestation is apparent, try sprinkling Bt powder (Bacillus thuringiensis) on the plants’ leaves. This organic bacteria is poisonous to caterpillars, moths and butterflies but will not harm plants or other beneficial insects. You can find Bt in any home and garden store. Look for a container with an artistic depiction of an especially vicious tomato hornworm on the label.
Another option is to invite natural predators. Braconid wasps prey on tomato hornworms, so plant dill and cilantro nearby to attract the wasps.If you see a hornworm with white egg sacs on its back, leave it alone, as those eggs are wasp egg sacs that will hatch and help take care of your problem.