Tomato Hornworms are large green caterpillars that feed on your tomato, eggplant, and pepper plants. The best way to protect your harvest is to simply remove these creatures by hand. You can kill them by placing them in a bucket of soapy water or, if you don’t want to kill them, you can try moving them to a designated plant far away from your main garden. You can also entice their natural predators, which include wasps, ladybugs, and lacewings, to visit in your garden. If you choose to use pesticides like BT (Bacillus thuringiensis) or permethrin, it’s important to know that these substances can be harmful to people, too, and may also kill beneficial insects and other pollinators.