Tomato Hornworms: Identification, Control & Prevention

Tomato hornworms are large green caterpillars (up to 5") with white/black markings, a rear horn, and eight V-shaped stripes. Found across US; devastate tomatoes, eggplant, peppers, potatoes. Blend perfectly with foliage.

Lifecycle

• Late spring: large moths lay eggs on leaf undersides; hatch ~1 week.
• Larvae feed 4–6 weeks, then cocoon in soil. Warm weather: 2–3 weeks.
• Moths emerge spring; lay eggs. Multiple generations in warm climates.

Identification

Daily patrol for eggs/small caterpillars. Signs:

• Dark green droppings (frass) on TOP of leaves → look underside for hornworm.
• Stems missing leaves; wilted leaves hanging; white cocoons nearby (parasitized).

Damage

Large leaf holes, severe defoliation, devoured flowers, fruit scarring. Sunscald on fruit from foliage loss.

Control

• Handpick (excellent for small gardens): drop in soapy water.
• Bt (Bacillus thuringiensis): stomach poison for caterpillars; safe for other life. Check extension for approved insecticides if large area.

Prevention

• Till soil start/end of season—destroys overwintering larvae (up to 90% mortality).
• Keep wasps—they parasitize hornworms (rice-grain larvae on caterpillar). Leave parasitized ones; they'll do little damage.
• Companion planting: dill, basil, marigolds interplanted with tomatoes repel hornworms and other pests.

Plants Affected

• Tomatoes
• Eggplant
• Bell Peppers
• Potatoes