Tomato: Tomato hornworm

categories: Tomato Tomato Insects Vegetables

revision date: 2023-04-12 12:00

Tomato hornworm larva close-up.
Tomato hornworm larva close-up
Photo by: W. Cranshaw, CSU

Biology

The tomato hornworm is the larva of a sphinx moth. The adult moth has a wingspan of up to 4″-5″. Wing color is generally mottled gray. Mature caterpillars may reach up to 5″ in length but are typically around 2″ long. They are generally pale green with some white markings, although dark purple hornworms are sometimes seen. The mature hornworms are characterized by a short, curved, green to reddish horn on the back end. The larvae feed on the leaves of tomato, potato, and related plants and may cause serious defoliation. Symptoms of feeding include leaves chewed down to the midrib and dark pellets of frass (excrement) on or under plants.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Hand-pick and kill hornworms. This is usually sufficient control for the home garden.
  • Natural enemies including birds, spiders, and parasitic wasps help control caterpillar populations. Avoid use of broad-spectrum insecticides which can kill beneficial insects.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

  • Apply Bt when first noticed. Hornworms will soon quit feeding but may remain on plant a few days.
  • If Bt is chosen, be sure to apply when insect is feeding.
  • The best time to apply is when caterpillars are young.
  • Use a spreader-sticker with liquid Bt formulations.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

Additional Image