How Do I Stop Tomato Hornworms?

“Tomato killer caterpillars are a problem in my garden. How do I prevent and catch them before they kill my plant?” Question from Karen of West Des Moines, Iowa.

Answer: The key to stopping these destructive pests is knowing their life cycle and how to stop them at the egg stage. Not only do these large hawkmoth caterpillars attack tomatoes, but they will also dine on eggplant, pepper, and potato plants. They are a common pest across much of North America. The moths survive winter and emerge in spring when the soil warms.

The female moths lay eggs on the tops or bottoms of leaves in the evening, so check your tomato leaves each morning for single pearly eggs of green or greenish yellow. (Click here for an image of an egg.) Smash them as soon as you see them. Or you can simply remove any leaves with eggs and smash them. This process takes little time, but it is worth the effort. If you keep it up, hornworms won’t have a chance to hatch on your plants.

If you miss a few, simply remove the caterpillars as you see them and either smash them or place them in a dish of soapy water. You don’t want to use harsh chemicals on your tomatoes because they will hurt the bees and other insects visiting your plants.

This hornworm has been parasitized by wasps.

If you see a hornworm dotted with white eggs, leave it alone. It has been parasitized by wasps that will kill the caterpillar quickly. These wasps are your friends, and new wasps will emerge from the infected hornworm to naturally destroy your hornworm population.

Follow these instructions and your tomatoes will be hornworm free.

Happy tomato growing!

Jessie Keith

Black Gold Horticulturist