Natural Enemies: Parasitic Wasp

Parasitic wasp cocoons on a hornworm.

Parasitic wasp cocoons on a hornworm.
Sue Watts, 2022, SC Botanical Gardens, Clemson University

I recently came across this caterpillar in the garden. The bright green body first attracted my attention, and then I saw the white additions to its body. This caterpillar is beautiful but doomed; it may even be dead.

A member of the genus Manduca, this is either a tobacco or tomato hornworm. Both are hawkmoth caterpillars that feast on Solanaceae leaves. Their attraction to food crops in the Solanaceae family, including tomatoes, potatoes, and eggplant, make them many gardeners’ foes. However, nature has a control method. A tiny parasitic wasp (Cotesia congregata) lays eggs in the caterpillar. Once hatched, the larvae feed on the caterpillar’s insides. Finally, they emerge from the body and spin this white cocoon. A single caterpillar can be the host for up to 300 wasps; this gives an idea of how tiny they are. These wasps are one of many that provide pest population control for the gardener. If pesticides are applied, this free natural pest control service disappears.

For more information, see HGIC Blog Hornworms on the Tomatoes and HGIC 2820, Natural Enemies: Predators and Parasitoids.

If this document didn’t answer your questions, please contact HGIC at or 1-888-656-9988.

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