Eggs that are not consumed by lacewings, ladybeetles or other predators hatch in about a week, and the caterpillars start eating tomato leaves and rasping surface holes in green fruits. Either way, female moths find a promising tomato plant and scatter single light green eggs on both sides of leaves. The hornworms on your tomatoes this year may have emerged from last year’s tomato patch, or the adult moths may have flown in from afar. The Tomato Hornworm Life Cycle A young tomato hornworm dines on a green tomato Both species are native to the Americas, being larvae of two sphynx or hawk moths that fly mostly at night. The horns of tomato hornworms are blue-black, while those of tobacco hornworms are reddish. Hornworms earn their names with their fleshy ‘horns’, which they raise to frighten enemies. In northern states, you are probably seeing true tomato hornworms ( Manduca quinquemaculata), while in warmer areas tobacco hornworms ( Manduca sexta) are also likely to appear.

These are the signs that tomato hornworms have arrived in your garden. First you notice part of an outer leaf missing, then a small branch eaten to a nub, or maybe your eyes land on dark green pebbles of caterpillar poo (frass). The most dreaded tomato pests in both of the Americas are tomato hornworms, which become active in early summer, just as tomato plants grow to full size.

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