How do you get rid of tomato hornworms? Hand-pick them. University of Minnesota Extension calls picking hornworms off plants the most effective control; drop them into soapy water. Check plants twice a week and search at dusk with a flashlight. Use Bt only on young caterpillars, and leave any hornworm covered in white wasp cocoons.
Key takeaway: The tomato hornworm (Manduca quinquemaculata) is a huge green caterpillar that can strip a tomato plant fast. It also feeds on pepper, eggplant and potato.
| Fact | Detail | Source |
|---|---|---|
| Size | Up to 4 in (10 cm) long | UMN Extension |
| Markings | 8 V-shaped white marks per side, dark horn | UMN, Rutgers |
| Look-alike | Tobacco hornworm: 7 diagonal stripes, red horn | UC IPM, Illinois |
| Feeding time | 3–4 weeks as a caterpillar | UMN, UC IPM |
| Damage speed | 1–2 worms can strip a 5 ft (1.5 m) plant in under 3 days | Illinois Extension |
| Moth wingspan | Up to 5 in (12 cm) | UC IPM |
| Overwinters | As pupae in the soil | UMN Extension |
What Does a Tomato Hornworm Look Like?
It is a large green caterpillar with a horn on its rear end. UMN Extension says tomato hornworms reach up to 4 in (10 cm), and large ones have eight white, V-shaped marks on each side. Rutgers offers a memory trick: V8, for eight V marks. Small caterpillars are pale with no markings.
How Is It Different From the Tobacco Hornworm?
Count the stripes and check the horn. UC IPM says the tobacco hornworm has seven diagonal stripes on each side, while the tomato hornworm has eight chevrons. Illinois Extension adds that the tobacco hornworm’s horn is curved and red, and the tomato hornworm’s is straighter and blue-black. Both damage tomatoes the same way.
What Is the Tomato Hornworm Life Cycle?
Adults are large hawk moths. UMN Extension says the pupae spend winter in the soil, moths emerge in spring and lay smooth, light green eggs on leaves. Caterpillars feed for three to four weeks, drop to the soil to pupate, and a second generation follows in midsummer. UC IPM notes two generations a year in most areas.
What Damage Do Tomato Hornworms Cause?
They eat leaves, blossoms and fruit. UC IPM says heavy populations can strip plants and scar fruit. Illinois Extension warns that one or two worms can defoliate a 5 ft (1.5 m) tomato in less than three days. UMN notes the last caterpillar stage eats nearly as much as all younger stages combined, so damage seems to appear overnight.
If fruit also ripens poorly, see why tomatoes are not turning red.
How Do You Find Hornworms on Plants?
Look for droppings first. UMN describes dark green or black droppings that stand out on leaves, and Rutgers says the pellets can look like small stars. Rutgers also notes caterpillars are most active at dusk or dawn, so search with a flashlight. Illinois Extension says a UV black light makes foliage look red-orange and caterpillars bright green.
- Inspect plants at least twice a week in summer.
- Scan the upper leaves, where feeding starts.
- Follow fresh droppings up to the caterpillar.
- Check leaf undersides at dusk with a flashlight.
- Shake the plant over cardboard to dislodge hidden worms.
Which Natural Enemies Control Tomato Hornworms?
Braconid wasps are the best known. UMN Extension says the wasp Cotesia congregatus lays eggs on the hornworm, and its larvae feed inside before spinning cocoons that look like white rice. Leave those hornworms in place so new wasps emerge. Lady beetles, green lacewings and paper wasps also eat eggs and young caterpillars.
When Should You Use Bt or Other Sprays?
Only if hand-picking fails. Small worms are easier to kill. UMN says pesticides are generally not necessary, Bacillus thuringiensis var. kurstaki (Bt) must be eaten to work, targets caterpillars and does not affect bees. Spinosad works for one to two weeks but is toxic to bees when wet. Always follow the label.
For other soft options, see our neem oil for plants guide. For sap-sucking insects on the same crops, read our guide to aphids and spider mites.
How Do You Prevent Hornworms in a Greenhouse or Hydroponic Setup?
Keep moths and pupae out. UMN advises removing weeds such as horsenettle, jimsonweed and nightshade that host eggs. Because caterpillars pupate in soil or growing media, clear old media after the season; Illinois says tilling can destroy up to 90% of overwintering pupae. Regular checks help, along with sticky traps for monitoring other pests.
FAQ About Tomato Hornworms
How big do tomato hornworms get?
Up to about 4 in (10 cm) long.
What do tomato hornworms turn into?
Five-spotted hawk moths, Rutgers says.
Should I kill a hornworm with white cocoons?
No, leave it so the parasitic wasps can emerge.
Do hornworms eat peppers?
Yes, also eggplant and potato.
Does Bt harm bees?
UMN says Bt does not affect bees.
Sources
- University of Minnesota Extension — Tomato hornworms in home gardens
- UC Statewide IPM Program — Hornworms (Tomato)
- University of Illinois Extension — Hornworm
- Rutgers Cooperative Extension FS1389 — Hornworms in the Home Garden
- Photo credits (Wikimedia Commons, edited with titles): Manduca quinquemaculata larva by Whitney Cranshaw, Colorado State University, Bugwood.org (CC BY 3.0 us); Manduca quinquemaculatus – Five-spotted Hawk Moth (15122473855) by Andy Reago & Chrissy McClarren (CC BY 2.0); Tobacco Hornworm 5 by Max Wahrhaftig by Max Wahrhaftig (CC BY-SA 3.0); Pepper and tomato seedling trays at Boğaziçi University 2026 by Furkan Akkurt (CC BY-SA 4.0)