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Tomato Hornworm

Pest

The tomato hornworm is a large, green caterpillar that feeds voraciously on the foliage and fruit of tomato plants. Because these pests can strip a plant of its leaves in just a few days, they pose a significant threat to the health and productivity of your garden.

Symptoms by part

Leaves

Large sections of leaves are missing, often starting from the top of the plant and moving downward, leaving only the main veins behind.

Leaves

Small, dark, pellet like droppings, known as frass, appear on the leaves or the ground beneath the plant.

Causes

  • The presence of adult sphinx moths that lay eggs on the undersides of leaves during the growing season.
  • A lack of natural predators like parasitic wasps or ladybugs in the garden environment.

Could be confused with

  • Tobacco Hornworm · The tobacco hornworm has a red horn and white diagonal stripes, whereas the tomato hornworm has a blue green horn and V shaped white markings.
  • Slugs · Slugs leave behind a shiny slime trail on the leaves, which hornworms do not produce.

Treatment

  1. Handpick the caterpillars off the stems and leaves during the early morning or evening when they are most active.
  2. Drop the collected caterpillars into a bucket of soapy water to dispose of them.
  3. Apply Bacillus thuringiensis to the foliage, focusing on the undersides of leaves where the larvae feed, follow the label.

Without chemicals

  • Use floating row covers early in the season to prevent adult moths from laying eggs on your plants.
  • Till the soil around your plants in the fall or spring to destroy pupae overwintering in the ground.
  • Plant flowers like dill, marigolds, or borage nearby to attract beneficial insects that prey on hornworms.

Chemical options

  • Bacillus thuringiensis, apply as a spray to foliage, follow the label.

Preventing it

  • Keep your garden beds free of weeds that might host the moths.
  • Rotate your crops each year to disrupt the life cycle of the pest.
  • Encourage natural predators by avoiding broad spectrum insecticides.

Season

The warm growing season.

Spread risk

Moderate

Severity

High

When to act

Act as soon as you notice missing foliage or dark droppings on the leaves. If the plant has been completely defoliated and the stems are brittle, it is best to remove and compost the plant.

Think it's Tomato Hornworm?

This guide covers the general picture. Pocket Botanist looks at your actual plant from a photo and tells you what's really going on, how serious it is, and what to try first. Identification and a health check are free.

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Questions people ask

Are tomato hornworms harmful to humans?
No, they are harmless to touch and do not bite or sting, though their horn can feel slightly prickly.
Why do I see white cocoons on the back of the caterpillar?
Those are the cocoons of a parasitic wasp, which is a beneficial insect that kills the hornworm. You should leave these caterpillars alone so the wasps can hatch and help control the population.

Plants it affects

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This guide was generated with AI and is general information, not horticultural advice. Read about how we build these guides.