Tomato Hornworms (2024)

FAQs

How many hornworms will you find on a tomato plant? ›

The female lays its eggs underneath the leaves of the host plant and the larvae hatch in only 3 to 5 days. There are two or more generations per year. This is an excellent example of a case where hand picking is the only “insecticide” necessary. That's because there is usually only one hornworm per plant, rarely two.

Yet here's the most important reason to let the homely hornworm live to see another day: he's a valuable garden helper on two counts. If his back is covered with a row of little white eggs, (I've personally never seen this), it means he's playing host to a beneficial tiny insect called the braconid wasp.

As you baby your plants with tomato fertilizer spikes, plenty of water, and a little TLC, keep them secure with these anti-hornworm gardening tips: Lure them away with basil, marigolds, or dill. Apply insecticidal soap to plants to kill smaller worms.

Hornworms are voracious. Tobacco hornworms (pictured) and tomato hornworms eat the tops of stems at night, then disguise themselves under leaves during the day.

Catch hornworms in action at dusk, dawn or nighttime, when these pests come out to feed in the open.

Results of Tomato Hornworm Infestation

If left undisturbed on a plant, hornworms can completely defoliate your garden vegetables in just a few days. With the larvae eating the leaves and new stems of plantings, the planting may die, although plants can typically recover if the hornworms are removed early.

ATTRACT BRACONID WASPS TO YOUR GARDEN

A natural enemy of the tomato hornworm is the braconid wasp (Cotesia congregatus), a small, non-stinging parasitic wasp that deposits its eggs just under the skin of soft-bodied caterpillars. The eggs hatch and the larvae feed on the hornworm until they are ready to pupate.

Ladybugs and green lacewings are the most common natural predators that you can purchase. Common wasps are also vigorous predators of tomato hornworms. Tomato caterpillars are also prey to braconid wasps.

The most preferred food for breeding adults as well as their baby birds, like downy woodpeckers, Baltimore orioles, bluebirds, flycatchers, and sparrows are fat, juicy caterpillars – like the tomato hornworms.

The essential oils in the marigold act as a repellent to many insects, including the moth that lays the tomato hornworm. Plant marigolds around crops that attract tomato hornworms, as well as throughout the garden. Beneficial insects are the most effective means of keeping tomato hornworms in check.

What is the enemy of tomato hornworm? ›

There are many natural enemies of the tomato hornworm. Various general predatory insects such as lady beetles and green lacewings often prey upon the egg stage and on young caterpillars. Another important predator is paper wasps, Polistes spp.

The Pairing: Apart from being culinary buddies, basil and tomatoes are excellent garden companions. How It Works: Basil helps repel thrips, whiteflies, and even tomato hornworms. Plus, some gardeners believe basil may enhance the flavor of tomatoes.

A tomato hornworm is the larva of a hawk moth, also called a hummingbird moth. The moths emerge from the soil in late spring or early summer, then lay their eggs singly on the undersides of a host plant's leaves. The tiny caterpillars hatch in about a week and quickly grow as they feed.

Damage caused by tomato hornworms

Tomato is the host of choice, but they have also been found on potato, eggplant and pepper. There are many weeds that serve as alternate hosts, including horsenettle, jimsonweed and nightshade. Large numbers of caterpillars can occur in home gardens and can quickly defoliate plants.

Eggs are deposited on the undersides of leaves at night. Each moth deposits 1 to 5 eggs per plant visit and may lay up to 2,000 eggs. First generation larvae are present by late May or early June. After feeding for 3 weeks, the larvae burrow into the soil and pupate.

The answer to finding these pests the fastest is actually Ultra Violet Black lighting! The Tomato Hornworm may be superior in the daylight blending in with the plants foliage but at night, under the right lighting they glow like they are radioactive!

Life cycle of tomato hornworms

Tomato hornworms survive winters as pupae and emerge as adult moths in spring. After mating, females deposit oval, smooth, light green eggs on lower and upper leaf surfaces. Caterpillars hatch, begin to feed, and are full-grown in three to four weeks.

The lifespan of the adult is usually 2 to 3 weeks. In order to begin the life cycle again, place a plant from the Solanaceae family (e.g., tomato plant, tobacco plant, jimsonweed) in the habitat. On the third night after emergence, females begin to deposit eggs on the underside of leaves.