Tomato Hornworm
Manduca quinquemaculata
📖 Description
Tomato hornworms are among the largest and most voracious caterpillars found in home gardens. A single hornworm can defoliate an entire tomato plant in just a few days, and their green coloration makes them extremely difficult to spot against the foliage. Often, gardeners discover them only after finding large green droppings on the ground below severely damaged plants. The white cocoons sometimes visible on their backs are the larvae of parasitic braconid wasps, which are beneficial and should be left alone — the wasps will hatch and parasitize more hornworms. The adult moth, known as the five-spotted hawkmoth, is a large, fast-flying pollinator.
⚠️ Symptoms to watch for
- Rapid defoliation — entire stems stripped of leaves overnight
- Large dark green droppings (frass) on lower leaves and ground
- Chewed green or ripening fruit
- Stems with large sections of bark stripped
- Missing leaves at the top of the plant first
- Green caterpillars difficult to spot against foliage
🩹 Treatment
- Hand-pick caterpillars and drop in soapy water (organic)
- Leave parasitized hornworms in place to release more wasps (organic)
- Apply Bt (Bacillus thuringiensis) to small caterpillars (organic)
- Spray with spinosad-based insecticide (organic)
- Release Trichogramma wasps to parasitize eggs (organic)
- Apply carbaryl or permethrin spray (chemical)
🌿 Organic treatments
- Hand-pick caterpillars and drop in soapy water
- Leave parasitized hornworms in place to release more wasps
- Apply Bt (Bacillus thuringiensis) to small caterpillars
- Spray with spinosad-based insecticide
- Release Trichogramma wasps to parasitize eggs
🧪 Chemical treatments
- Apply carbaryl or permethrin spray
🛡️ Prevention
- Till soil in fall to destroy overwintering pupae
- Rotate crops away from solanaceous plants
- Monitor for frass and early feeding damage in mid-summer
- Encourage parasitic wasps by planting umbel flowers
- Use floating row covers on young transplants
- Check plants twice weekly during growing season
🪴 Affected plants
- Tomatoes
- Peppers
- Eggplant
- Potatoes
- Tobacco
- Moonflowers
🦋 Natural predators
- Braconid Wasps
- Green Lacewings
- Birds
🌱 Host plants
- Solanum lycopersicum
- Solanum tuberosum
- Datura spp.
🔄 Lifecycle
- Adult moths emerge from overwintering pupae in late spring.
- Females lay spherical green eggs singly on leaf undersides.
- Eggs hatch in 3-5 days.
- Caterpillars feed and grow through 5 instars over 3-4 weeks, reaching 3-4 inches.
- Mature caterpillars drop to soil and pupate underground.
- Second generation adults emerge in mid-summer.
- Pupae overwinter 4-6 inches deep in soil.
- One to two generations per year.
📅 Season
- Summer (June through August)
🔎 Appearance
- Enormous bright green caterpillars with white diagonal stripes and a distinctive horn at the tail end.
- Can grow to 4 inches long.
- Often found clinging upside down on tomato stems.
- White cocoons of parasitic wasps may be visible on their backs.
💥 Damage level
- High
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- North America
- Central America
- South America
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