Caterpillar Identification

Caterpillar identification is key in understanding whether a caterpillar is a friend or foe to your vegetable patch.

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Note that caterpillars have stinging hairs or other irritants, so it’s a good idea to use gloves when handling ones that you don’t recognize. Let’s investigate four common caterpillars and what they mean to your garden.

1. HORNWORMS

There are two varieties of hornworms: tomato hornworms and tobacco hornworms. These plump, light-green caterpillars can grow as thick and long as your finger which makes caterpillar identification easy. Diagonal white lines vary from seven on tobacco hornworms to eight on tomato hornworms, with more of a V-shape on the latter. Both have reddish dots along the body and a curved, pointy horn on the rear, which is red on tobacco hornworms and black on tomato hornworms.

As expected from their names, these caterpillars devour leaves of tomatoes, potatoes, tobacco, peppers, eggplants and others in the Solanaceae (nightshade) family. However, the adult moths pollinate night-blooming flowers. The tobacco hornworm becomes the Carolina sphinx moth (Manduca sexta) and the tomato hornworm becomes the five-spotted hawk moth (Manduca quinquemaculata). Large, strong fliers, with a wingspan up to 5½ inches, their scientific names give clues to how many pairs of yellow-orange spots decorate the body (six on the sphinx moth, five on the hawk moth).

The moths resemble hummingbirds. Each has a long proboscis perfectly suited for reaching inside tubular flowers, such as morning glories, sweet potatoes, moonflowers, petunias, Datura, and four-o'clocks. As they drink deeply of the flower’s nectar, the moths spread pollen and help these plants develop fruits. The moths themselves pose no risk to the nightshade family, other than laying their eggs on them for the larva to enjoy.