The tomato hornworm is a well-known pest throughout the United States because of its destruction of tomato, pepper, eggplant, and other vulnerable vegetable plants. These pests will consume entire leaves, stems, and even fruits if nothing else is available. They will even feed on tobacco plants.
Despite their large size, tomato hornworms are difficult to spot because of their natural ability to blend in with their surroundings. Gardeners often discover significant damage during the summer months that has already been done to their plants before they know they have a pest problem.
Tomato hornworms are large caterpillars that are 3 to 4 inches long with green bodies that have seven white stripes and a red or black horn on their rear end.
Their adult counterparts are large moths with a 4 to 5-inch wingspan and brown or grey bodies with brown or orange spots and white markings on their back wings.
Adults mate during late spring, depositing green eggs on the underside of leaves. In less than a week, the eggs hatch and larvae emerge to feed until they mature and drop into the soil to pupae, emerging in 2 to 4 weeks as an adult.
The larvae of tomato hornworms can be controlled naturally from gardens by picking any that are exposed and disposing them into a container of warm soapy water. To eliminate larvae that are hidden, look for black spots on the leaves and near the base of the plant, then spray the foliage and area with water to disturb and reveal the pests.
Introducing beneficial predators such as lacewings, lady beetles, and trichogramma wasps to your garden or greenhouse can help reduce pests numbers since they attack the eggs.
Tilling your garden after harvesting helps destroy the larvae that pupae in the soil. This method not only destroys the pest but allows other predators like birds to feed on them once exposed.