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Tomato Hornworms: Large but Harmless Caterpillars

A gardener found two large caterpillars (4–5 inches) on tomato plants, describing them as "very fat" and reactive when touched. They're concerned about danger and recurrence, and seek natural control methods.

Identification: Tomato Hornworms

These are tomato hornworms (Manduca quinquemaculata), the larvae of the five-spotted hawk moth. Despite their size and dramatic appearance, they are harmless to humans—they do not bite or sting.

Natural Control Methods

Hand-picking: Daily inspection and manual removal is most effective in small gardens
Spinosad: A natural, soil-derived insecticide highly effective against caterpillars; safe for home gardens
Beneficial insects: Braconid wasps parasitize hornworms; leave parasitized caterpillars (with white cocoons) in place

For more on spinosad, see livingwithbugs.com/spinosad.html. Hornworms do not "return season after season" from the same individuals—new moths lay eggs each year.

Pests: Tomato Leaf Discoloration: Viral Infection vs. Fungal Disease; Shriveled, Brown Tomato Leaves: Root Stress, Not Disease; Tomato Seedling Sunburn After Moving Outdoors; Tomato Seedling Cold Tolerance and Fertilization Strategy; Tomato Fruit Set in Extreme Heat: Why Green Tomatoes Persist; Tomato Seed Germination: Light Determines Speed; Rescuing Overcrowded Container Tomato Seedlings; Tomato Plant Pruning: Suckers, Leaves, and Stems for Maximum Yield; Growing Tomatoes: America's Favorite Garden Vegetable; Complete Guide to Growing Tomatoes: From Seed to Harvest

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