Tobacco Hornworm Identification Guide
Manduca sexta
The tobacco hornworm is a large green caterpillar that feeds voraciously on tomato, pepper, tobacco, and other plants in the nightshade family. These conspicuous garden pests can rapidly defoliate plants but rarely require professional pest control.
Taxonomy
Tobacco Hornworm Coloration
Common color patterns to help identify tobacco hornworm
Tobacco Hornworm
Seasonal Activity
When tobacco hornworm are most active throughout the year
Where Tobacco Hornworm Are Found
Hover over states to see their names. Green regions indicate where tobacco hornworm have been reported.
Tobacco Hornworm Identification Guide
Physical Characteristics
Tobacco hornworms are among the largest caterpillars in North American gardens. Full-grown larvae reach 70 to 80mm long, about the size of an adult finger. Their bright green bodies blend in well with tomato and pepper leaves.
The most notable feature is the horn on the rear end. On tobacco hornworms, this horn is red or orange-red. The caterpillar also has seven diagonal white stripes on each side of its body. Small black breathing pores appear along the sides.
Young larvae are much smaller and harder to spot. They start as tiny pale green caterpillars only a few millimeters long. As they grow, they develop the stripes and horn. The head is green with small white markings.
Tobacco hornworms have three pairs of true legs near the head and five pairs of fleshy prolegs on the belly. These prolegs have tiny hooks that grip plant stems. This makes the caterpillars hard to pull off.
Adult Carolina Sphinx Moth
The adult form of the tobacco hornworm is the Carolina sphinx moth (Manduca sexta). People also call it a hawkmoth. These large moths have a wingspan of 9.5 to 12 cm. They are one of the largest moths in North America.
Adult moths have gray and brown forewings with wavy dark lines. The hindwings are gray with dark and light bands. Six pairs of orange-yellow spots run down the sides of the belly.
Carolina sphinx moths are strong fliers. They can hover in place while feeding, much like hummingbirds. They fly at dusk and dawn and visit tube-shaped flowers. Their long tongue can extend up to 10 cm to reach nectar deep in flowers.
Telling Tobacco Hornworms from Tomato Hornworms
These two species are often confused since they feed on the same plants and look similar. Here are the key differences:
Tobacco hornworm (Manduca sexta):
- Seven diagonal white stripes per side
- Red or orange-red horn
- Adult moth has six orange abdominal spots
Tomato hornworm (Manduca quinquemaculata):
- Eight V-shaped chevron markings per side
- Blue-black or dark horn
- Adult moth has five orange abdominal spots
Both species cause the same type of damage and respond to the same control methods. In practice, distinguishing between them is not essential for management.
Tobacco Hornworm Behavior and Biology
Lifecycle and Development
Tobacco hornworms go through four life stages: egg, larva (caterpillar), pupa, and adult moth. The full cycle takes 30 to 50 days in warm weather. It can take longer when it is cooler.
Eggs: Female moths lay eggs one at a time on the undersides of leaves. The eggs are round, about 1mm wide, and pale green. They hatch in 2 to 8 days based on the temperature.
Larvae: This is the stage that causes damage. Caterpillars grow for 3 to 4 weeks. They feed almost all the time, eating large amounts of leaves. Most feeding happens when they are full-sized. One mature caterpillar can strip a small tomato plant in 2 to 3 days.
Pupae: When fully grown, larvae drop to the soil and dig several inches deep. They form dark brown pupae. This stage lasts 2 to 4 weeks in summer. The last generation stays in the soil all winter.
Adults: Moths come out in late spring. They mate and start laying eggs within a few days. Adults live only 2 to 3 weeks. Most areas have two generations per year. Southern regions may see three.
Feeding Habits
Tobacco hornworms are specialists on plants in the nightshade family (Solanaceae). Their diet includes:
- Tomatoes (the most common host in gardens)
- Peppers (bell, hot, and ornamental varieties)
- Eggplant
- Tobacco
- Potatoes
- Petunias
- Jimsonweed and other wild nightshades
Caterpillars mainly eat leaves. They will also eat flowers, green fruit, and stems when leaves run out. They start feeding at the top of plants and work down. Their droppings are large, dark green pellets. You often find them on leaves and at the base of plants.
Feeding is heaviest in the early morning and evening. During the hottest part of the day, caterpillars rest on stems. Their green color helps them hide.
Natural Enemies
Many predators and parasites attack tobacco hornworms:
Braconid wasps: Small wasps in the genus Cotesia are the main natural enemy. Female wasps lay eggs inside the caterpillar. The larvae grow inside, then exit and spin small white cocoons on the caterpillar’s back. If you see a caterpillar covered in white cocoons, it is already dying.
Paper wasps: Polistes wasps hunt caterpillars to feed their young. They can reduce hornworm numbers in gardens.
Ground beetles: These and other ground-dwelling predators eat eggs, small larvae, and pupae in the soil.
Birds: Some bird species eat hornworms despite their large size.
Signs of a Tobacco Hornworm Problem
How to Spot an Infestation
Tobacco hornworms are often hard to see despite their large size. Their green color matches leaves almost perfectly. Look for these signs:
- Missing leaves: Entire leaves or large sections stripped from stems, especially at the top of plants
- Bare stems: Exposed branches where foliage has been consumed
- Dark droppings: Large green-black frass pellets on leaves and ground below plants
- Chewed fruit: Green tomatoes or peppers with gouged areas
- Damaged growing tips: Loss of terminal growth
Where to Look
Check plants carefully in early morning or evening when caterpillars are actively feeding. Examine:
- The undersides of leaves
- Along main stems, especially near the top of plants
- At the base of leaf petioles
- On fruit surfaces
Following a trail of droppings upward often leads right to the caterpillar. A black light flashlight makes hornworms glow, which helps you find them at night.
Control Methods for Tobacco Hornworms
Tobacco hornworms are garden pests that rarely need professional pest control. The following methods work well for homeowners:
Hand-Picking
The most direct and effective method for home gardens is simply removing caterpillars by hand. Check plants daily during peak season. Wear gloves if preferred, though the caterpillars are harmless. Drop collected hornworms into a bucket of soapy water or relocate them far from your garden.
This method works well because:
- Hornworms are large and easy to remove once located
- Even a few caterpillars cause noticeable damage
- No chemicals are involved
- Results are immediate
Biological Control with Bt
Bacillus thuringiensis var. kurstaki (Btk) is a natural soil bacterium that kills caterpillars when eaten. It comes as a spray or dust at garden centers. Bt works best on young larvae. You must reapply it after rain.
Key points about Bt:
- Effective only against caterpillars
- EPA-registered for use on food crops
- Works slowly: caterpillars stop feeding within hours but may take 2-3 days to die
- Breaks down in sunlight within a few days
Cultural Controls
Preventive practices reduce hornworm problems:
- Soil tilling: Tilling soil in fall and early spring kills pupae that overwinter. Over 90% of pupae die from normal tilling.
- Crop rotation: Moving tomatoes and peppers to different spots each year cuts down hornworm numbers.
- Companion planting: Some gardeners say that basil, marigolds, and dill help deter hornworms. There is limited scientific proof of this.
- Removing weeds: Getting rid of wild nightshades near gardens removes other plants that hornworms use.
When Chemical Control May Be Warranted
In large gardens or commercial operations where hand-picking is not practical, targeted insecticides may be needed. Products containing spinosad offer effective control. Always follow label directions and observe pre-harvest intervals when treating food crops.
References and Further Reading
Other Moths
Explore other species in the moths family
Commonly Confused With
Tobacco Hornworm are often mistaken for these similar pests
Where Tobacco Hornworm Are Found
Hover over states to see their names. Green regions indicate where tobacco hornworm have been reported.
Common Questions about Tobacco Hornworm
What is the difference between tobacco hornworms and tomato hornworms?
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Tobacco hornworms have seven diagonal white stripes on each side and a red horn on their rear. Tomato hornworms have eight V-shaped chevron markings and a blue-black horn. Both feed on the same plants and cause similar damage. The adult moths also differ: tobacco hornworm moths have six orange spots on their abdomen while tomato hornworm moths have five.
Are tobacco hornworms harmful to humans?
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No, tobacco hornworms are not harmful to humans. They cannot bite or sting. The horn on their rear end is soft and purely for show. They are harmless to handle, though they may thrash around when picked up. The main concern is the damage they cause to garden plants.
What plants do tobacco hornworms eat?
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Tobacco hornworms feed on plants in the nightshade family (Solanaceae). This includes tomatoes, peppers, eggplant, tobacco, potatoes, and petunias. They prefer leaves but will also eat flowers and green fruit. A single caterpillar can defoliate a small plant in just a few days.
How do I get rid of tobacco hornworms in my garden?
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Hand-picking is the most effective method for small gardens. Check plants in early morning or evening when caterpillars are most active. Drop them in soapy water or relocate them away from your garden. For larger infestations, Bacillus thuringiensis (Bt) is an effective biological control that targets only caterpillars.
What are the white cocoons on tobacco hornworms?
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The white cocoons are pupae of parasitic braconid wasps. These wasps laid eggs inside the caterpillar, and the larvae fed on its tissues. The caterpillar will soon die. If you see these cocoons, the caterpillar is already dying and does not need to be removed.
When are tobacco hornworms most active?
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Tobacco hornworms are most active from late spring through early fall, with peak activity in midsummer. Adults begin emerging in early June. Most plant damage occurs in July and August when caterpillars are largest. In warmer regions, there may be two or three generations per year.
What does a tobacco hornworm turn into?
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Tobacco hornworms transform into Carolina sphinx moths, also called hawkmoths or hummingbird moths. These large gray-brown moths have a wingspan of 9-12 cm and can hover at flowers like hummingbirds. They are nocturnal and visit night-blooming flowers for nectar.
With five years of hands-on experience in the pest control industry, George Schulz is a registered technician with the Virginia Pest Management Association and a proud third-generation professional in a family business that's been protecting homes for over 57 years. He manages and trains a team of service pros while also leading internal research efforts—recently spearheading a deep-dive review of thousands of documents on pest control materials to hand-pick the most kid and pet friendly, most effective solutions tailored specifically for homes in the DC metro area.