While the plants themselves don’t repel the hornworms, dill, clover, fennel, and sweet alyssum attract parasitic wasps that feed on hornworms. They lay eggs beginning the whole cycle over again.ģ. In the spring, the hibernating cocoons of this second generation will hatch and moths emerge from their holes. If it’s warm enough, there will be a first generation that matures into moths and lays a second generation that will overwinter in the soil of your garden. Then they drop off the plant and burrow into the soil to form their cocoon and transform into moths.

Over a period of three to four weeks, they go through five molts before becoming full-sized adult worms.

The larvae of these species hatch in late spring or early summer. When you pick up a hornworm, it may wrap around your finger and cling to your skin-an odd sensation that is sometimes unpleasant but not hazardous. The horn-like projection isn’t sharp enough to pierce the skin. Tomato hornworms are not poisonous to humans in spite of their frightening appearance.

Download tomato hornworm eggs