Tomato Hornworms: How to Find Them and Get Rid of Them
Tomato hornworms are big green caterpillars, up to 4 inches long with a horn at the rear, that can strip a tomato plant of leaves in days; the usual fix is to find them by their dark droppings or with a UV torch at night and pick them off by hand. In many US gardens, especially in the South, the “tomato hornworm” is really the tobacco hornworm, which has seven diagonal white stripes and a red horn rather than V-shaped marks and a dark horn. Bt works on young caterpillars. Leave any hornworm carrying white, rice-like cocoons: those are parasitic wasps that will kill it and attack others.
Hornworms are the larvae of large sphinx moths. Two species feed on tomatoes, peppers, eggplant and potatoes, and gardeners treat them the same way. This guide covers telling them apart, reading the clues they leave, finding them in the dark, when Bt is worth using, why some should be left alone, and what our analysis of iNaturalist records shows about when they appear.
Tobacco hornworm vs tomato hornworm
| Feature | Tomato hornworm | Tobacco hornworm |
|---|---|---|
| Scientific name | Manduca quinquemaculata | Manduca sexta |
| Side markings | V-shaped white marks, usually eight per side (UC IPM, NC State) | Seven diagonal white stripes with dark edges |
| Horn | Dark: black or bluish black (some sources say brownish) | Usually red |
| Adult moth | Five-spotted hawk moth: five pairs of orange spots on the abdomen | Carolina sphinx: six pairs of orange spots |
| Where commoner | More abundant in the North (Ohio State) | More common in the South; the one most often found on tomatoes (Mississippi State, Illinois) |
| Full-grown size | Up to 4 inches (about 100 mm); both species reach the same size | |
The horn colour is the quickest check, and Mississippi State points out the irony: the tobacco hornworm is the one you usually find on tomatoes. Stripe counts are less reliable than stripe shape. UC IPM and NC State give eight chevrons for the tomato hornworm, while Ohio State describes seven sideways V shapes, so look at whether the marks are straight diagonals edged in black (tobacco) or plain white Vs (tomato). Both species can occasionally be dark brown rather than green, according to Ohio State and Missouri.
Signs of hornworms: damage and droppings
Hornworms are hard to see because their colour matches the plant, so most gardeners notice the damage first.
- Bare stems at the top of the plant. Missouri says feeding generally starts on the upper leaves. Nevada extension describes stems left completely bare apart from the leaf veins.
- Speed. Nevada says two or three hornworms can defoliate an entire plant, and Mississippi State warns that a healthy plant on Monday can be nubs by Thursday, because appetite rises sharply near the end of the larval stage.
- Chewed fruit. UC IPM notes large pieces chewed from green fruit. Nevada says this can look like bird damage, and Missouri says fruit feeding is worse in dry weather.
- Droppings. This is the best clue. NC State describes hornworm frass as distinctively barrel-shaped, and Nevada says it is green when fresh and turns black as it dries. UC IPM calls them large, dark droppings beneath the plant.
Tomato hornworm poop: how to use it
Fresh frass on a leaf or on the ground points to a caterpillar directly above. NC State notes that frass around the stalk or in the upper leaves “can help to find nearby feeding larvae.” Green pellets mean recent feeding; black, dry ones may be days old.
Where do tomato hornworms hide during the day?
In the upper part of the plant, usually underneath. NC State’s scouting guidance says larvae feed within the upper two thirds of plants and are often found on the undersides of leaves, and Nevada says they sit towards the top of plants on the undersides of branches. They stretch along a stem and rely on camouflage rather than hiding in soil. Missouri suggests a trick for daytime searches: in fast-drying conditions, spray the plant with water, and the caterpillars’ movement makes them easier to spot.
Find them at night with a UV torch
Hornworms glow under ultraviolet light. Nevada, Illinois and Mississippi State extension all recommend going out after dark with a black light or UV torch, which makes the caterpillars stand out against the foliage. Mississippi State notes such lights are cheap and come as small torches. Search the top third of each plant first, then the undersides of leaves.
How to get rid of tomato hornworms
- Check daily from early summer. Nevada recommends daily searches for damage, frass, eggs and caterpillars.
- Handpick. For a few plants, picking them off and dropping them into soapy water is the method Missouri, Mississippi State and Nevada all give first. Nevada calls hand-picking one of the most effective ways to prevent population growth.
- Check for white cocoons before you kill one (see below). Leave parasitised hornworms on the plant.
- Use Bt only on small caterpillars. UC IPM and Missouri say Bacillus thuringiensis and spinosad are effective against smaller or very young larvae. Missouri adds that insecticidal soap works only on small caterpillars it touches directly.
- Avoid broad-spectrum sprays. Nevada warns they can trigger aphid outbreaks by killing the insects that eat aphids. Our guide to getting rid of aphids explains why, and our garden pest control guide covers what the label allows on edible crops.
- Disturb the soil after harvest. Missouri advises tilling to about six inches in autumn to destroy pupae, which overwinter five to six inches deep; Nevada says autumn or early spring. UC IPM says soil disturbance destroys pupae and stops adults developing.
Whatever you spray, follow the label for the crop, the rate and the days to harvest.
Tomato hornworm with white eggs: leave it
A hornworm covered in white, rice-like objects is not carrying eggs. NC State explains that the braconid wasp Cotesia congregata lays its eggs inside young hornworms; the wasp larvae feed inside, then emerge from the fourth or fifth instar caterpillar and spin white cocoons on its back. “Although the white bodies look like ‘eggs’, they are actually wasp cocoons,” NC State notes.
A parasitised hornworm eats roughly a fifth as much as a healthy one and dies before completing development, and NC State’s own threshold counts five parasitised worms as one healthy one. Missouri and Nevada both say to leave these on the plant so the next generation of wasps emerges; Missouri adds the wasps are harmless to humans. Other natural enemies include Trichogramma wasps on the eggs and Hyposoter exiguae on the larvae (UC IPM), stilt bugs that eat eggs, and paper wasps that carry caterpillars off to feed their young (NC State).
Tomato hornworm life cycle
| Stage | What happens | Source |
|---|---|---|
| Egg | Round to oval, about 1.5 mm, white to pale green, laid singly on leaves | UC IPM |
| Tomato hornworm baby | Newly hatched larvae are small, bluish to pale green, with a black horn | NC State |
| Caterpillar | Feeds 3 to 4 weeks through five or six instars; most feeding happens in the last one or two | UC IPM; Missouri; NC State |
| Pupa | Burrows into soil; dark brown with a handle-like tongue case; overwinters about 5 to 6 inches deep | NC State; Missouri |
| Moth | Large sphinx moth, wingspan 3 to 5 inches | Nevada; UC IPM |
UC IPM says development takes about two months in summer, with two generations a year in most areas. NC State records two to three generations in North Carolina, with adults emerging from early June and most damage in July and later.
When hornworms appear: what the iNaturalist records show
Our analysis of US research-grade iNaturalist records for the tobacco hornworm, which covers both the caterpillar and the moth, shows a late peak. The index is its share of everything recorded each month, scaled so the yearly average is 100. It stays below average until June, at 86, then climbs to 222 in July and 344 in August, holds at 293 in September and only drops back in October. We could not include the tomato hornworm itself: research-grade records for it were not available in our pull.
Set beside two other garden pests, the timing is distinct. Japanese beetles peak in July and fall away sharply in September; see how to get rid of Japanese beetles. Aphids rise through August alongside hornworms. In practice, daily checks matter most from July to September, when fruit is ripening. Slugs, the other common tomato-bed pest, are covered in how to get rid of slugs.
Tomato hornworm moth
The adults are hawk moths, sometimes called hummingbird moths because they hover at flowers, as Nevada notes. Mississippi State describes large, jet-shaped moths with mottled grey wings and red to yellow spots on the abdomen, seen at dusk or dawn around tomato plants, where they lay eggs on the undersides of leaves. Ohio State says both are nocturnal pollinators of night-blooming flowers such as moonflowers, petunias and honeysuckle. The five-spotted hawk moth flies from late June to early September; the tobacco hawk moth is mainly active from July to September.
Frequently asked questions
Should I get rid of tomato hornworms?
Usually yes on tomatoes, because Nevada extension says two or three can defoliate a whole plant. Handpicking is enough in most gardens. Two exceptions: leave any hornworm carrying white cocoons, since those wasps attack other hornworms, and if you want the moths, Nevada notes some gardeners tolerate a few. The adult moths are pollinators of night-blooming flowers.
Is it safe to touch tomato hornworms?
Yes. Despite its look, the horn is harmless, as Mississippi State Extension says, and none of the extension sources we reviewed describe hornworms as venomous. Gardeners handpick them routinely. Missouri adds that the parasitic wasps whose white cocoons you may see on a hornworm are harmless to humans. Wash your hands afterwards if you have handled plants treated with any pesticide.
What will a tomato hornworm turn into?
A five-spotted hawk moth, Manduca quinquemaculata, a large grey sphinx moth with five pairs of orange spots on its abdomen. The tobacco hornworm becomes the Carolina sphinx moth, with six pairs. Both have wingspans of 3 to 5 inches according to Nevada extension, hover like hummingbirds and, as Ohio State notes, pollinate night-blooming flowers.
Where do tomato hornworms hide during the day?
Near the top of the plant, under leaves and along stems. NC State says larvae feed in the upper two thirds of plants and are often on the undersides of leaves, and Nevada says they sit towards the top on the undersides of branches. Look directly above fresh droppings, or come back after dark with a UV torch, which makes them glow.
What does tomato hornworm poop look like?
Large, dark, barrel-shaped pellets. NC State describes hornworm frass as distinctively barrel-shaped, and Nevada extension says it is green when fresh and turns black as it dries. You will usually find it on the leaves below a feeding caterpillar or on the ground under the plant, which makes it the most useful clue for locating a well-camouflaged hornworm.
Sources
- University of California Statewide IPM Program, Pest Notes: Hornworms (home and landscape) and Tomato Pest Management Guidelines: Hornworms.
- NC State Extension, Tobacco Hornworms and Tobacco and Tomato Hornworm (tobacco grower information).
- University of Missouri Integrated Pest Management, Caterpillars ‘Horn In’ on Tomato Plants (2021).
- University of Nevada, Reno Extension, Fact Sheet 23-33, A Northern Nevada Homeowner’s Guide to Identifying and Managing Tobacco and Tomato Hornworms.
- Mississippi State University Extension, How to Manage Hornworms on Tomatoes.
- University of Illinois Extension, Hornworm alert: Be on the lookout (2024).
- Ohio State University Extension, ENT-0094, The Sphinx Moths of Ohio.
- The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026.
