Paper wasps and other parasitic wasps in the Trichogammid species also eat hornworms. What plants repel tomato hornworms? Plant mums, marigolds, nasturtiums, and petunias to keep hornworms away.

John E. Woodmansee Photo: Tobacco hornworm on a tomato plant that has been attacked by a parasitic Braconid wasp. The white capsules on its back are the pupal stage of the tiny wasp. Braconid larvae ...