Common garden caterpillars: ID by damage and color

Caterpillars -- the larval stage of moths and butterflies -- are among the most diverse and visually distinct garden insects. They range from destructive crop pests to the larvae of beloved pollinators. Correct ID matters because some caterpillars warrant intervention, others are harmless or.

Caterpillars — the larval stage of moths and butterflies — are among the most diverse and visually distinct garden insects. They range from destructive crop pests to the larvae of beloved pollinators. Correct ID matters because some caterpillars warrant intervention, others are harmless or beneficial, and a few (monarch, swallowtail) should be actively protected.

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Tomato hornworm (Manduca quinquemaculata)

One of the largest caterpillars in North American gardens — 3–4 inches at maturity. Per Penn State Extension, tomato hornworm is bright green with seven diagonal white stripes on the sides and a distinctive black horn at the rear. The body is thick and smooth.

Damage: Ragged defoliation on tomato, pepper, eggplant, and potato. Damage begins in the upper canopy. The first sign is often frass — dark green, granular, pellet-shaped droppings — on leaves below.

Management: Hand-pick from plants. Per Penn State Extension, hornworms covered in white projections (braconid wasp cocoons) are parasitized — leave these; the wasps are more valuable than killing one hornworm. Bt (Bacillus thuringiensis (BT spray)) applied to foliage is effective on young caterpillars.

Confusion: Tobacco hornworm (Manduca sexta) is nearly identical but has 6 diagonal stripes and a red horn. Per NC State Extension, both species are managed identically.