Tomato Hornworm: Identification, Damage, and Control

title: "Tomato Hornworm: Identification, Damage, and Control"

Tomato hornworm (Manduca quinquemaculata) on a tomato stem showing diagnostic white V-marks and red rear horn — Photo: Unsplash

By Thomas Joseph Published 2026-06-10 Updated 2026-06-13 Reviewed by Thomas Joseph 8 min read

Tomato hornworms are among the most destructive garden caterpillars in North America. A single large larva can strip the foliage from an entire branch in one to two days. They are also remarkably difficult to spot — their green coloration matches tomato stems almost perfectly, and they feed on the upper part of the plant where they are hidden by leaves.

I don't grow tomatoes here in Melville, but the Extension research on hornworm biology and management is thorough, and this guide draws from it.

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Identification
Damage Pattern
Lifecycle
Finding Hornworms on Your Plants
Control Methods
Biological Control: The Braconid Wasp
Common Situations
Frequently Asked

Reader questions

Questions from other readers about this guide. Ask your own — if it's a good question, the answer goes here for the next reader.

How do I find tomato hornworms?

Per Penn State Extension, look for frass (dark green pellets) on leaves below active feeding sites, then look up the plant from there. At night, a UV blacklight flashlight will make hornworms fluoresce bright green against the plant. This is the most reliable detection method. Per University of Minnesota Extension, hornworms are most active in morning and evening, which is the best time to inspect.

Should I kill the hornworm with white eggs on its back?

No. Per University of Minnesota Extension, those white structures are not eggs but the cocoons of braconid wasp larvae that have already completed their internal feeding and emerged. The wasp is *Cotesia congregata*, an important natural enemy of hornworms. The parasitized caterpillar is already dying and will not feed normally. Leave it in place -- the wasps that emerge will seek out additional hornworms in your garden.

When should I apply Bt for hornworms?

Per UC IPM, Bt kurstaki is most effective on young, small caterpillars (early instars). For best results, begin scouting for hornworms as soon as transplants are in the ground and apply Bt at first evidence of egg hatch or small caterpillar feeding. Large caterpillars over 2 inches are significantly harder to kill with Bt. Evening application is preferred because Bt breaks down in UV light and caterpillars are most active after dark.

What plants besides tomatoes do hornworms attack?

Per University of Minnesota Extension, both *Manduca quinquemaculata* and *M. sexta* attack all members of the Solanaceae family: tomato, pepper, eggplant, potato, and tomatillo. They will also feed on dill and occasionally other plants. Inspecting all solanaceous crops together is good practice -- a hornworm infestation is rarely confined to just the tomatoes. --- > Recommended gear: Best BT Spray: Bacillus thuringiensis for Caterpillar Control — our buyer's guide covering picks for every budget, ranked by Extension publication consensus and personal use.

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Tomato Hornworm: Identification, Damage, and Control

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Tomato Hornworm: Identification, Damage, and Control

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Kill caterpillars, spare everything else

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