Green Tomato Hornworm
tobacco hornworm
(Image credit: lauraag)

You may have walked out to your garden today and asked, “What are the big green caterpillars eating my tomato plants?!?!” These odd caterpillars are tomato hornworms (also known as tobacco hornworms). These tomato caterpillars can do significant damage to your tomato plants and fruit if not controlled early and quickly. Keep reading to learn more about how you can kill tomato hornworms.

Identifying Tomato Hornworms

green and black hornworms

Image by Beverly Nash

Tomato hornworms are easy to identify. They are bright green caterpillars with white stripes and a black horn coming off the ends. Occasionally, the tomato hornworm will be black instead of green. They are the larval stage of the hummingbird moth.

Normally, when one tomato hornworm caterpillar is found, others will be in the area as well. Examine your tomato plants carefully for others once you have identified one on your plants.

Tomato Hornworm - Organic Controls to Keep Them Out of Your Garden

The most effective organic control for these green caterpillars on tomatoes is to simply hand pick them. They are a larger caterpillar and easy to spot on the vine. Hand picking and placing them in a bucket of water is an effective way to kill tomato hornworms.

You can also use natural predators to control tomato hornworms. Ladybugs and green lacewings are the most common natural predators that you can purchase. Common wasps are also vigorous predators of tomato hornworms.

Tomato caterpillars are also prey to braconid wasps. These tiny wasps lay their eggs on the tomato hornworms, and the larva literally eat the caterpillar from the inside out. When the wasp larva becomes a pupa, the hornworm caterpillar becomes covered with white sacks. If you find a tomato hornworm caterpillar in your garden that has these white sacks, leave it in the garden. The wasps will mature and the hornworm will die. The mature wasps will create more wasps and kill more hornworms.

Finding these green caterpillars on tomatoes in your garden is frustrating, but they are easily taken care of with a little extra effort.

Heather Rhoades
Founder of Gardening Know How

Heather Rhoades founded Gardening Know How in 2007. She holds degrees from Cleveland State University and Northern Kentucky University. She is an avid gardener with a passion for community, and is a recipient of the Master Gardeners of Ohio Lifetime Achievement Award.