When you find a tomato hornworm on your plants, your first move should be to look at its back before you touch it. Check for small white rice-shaped cocoons sticking up from the caterpillar's skin. These cocoons change everything about how you should respond. If you see them, leave that hornworm right where it sits. If the back is clean, grab it and get it out of your garden.
I found my first hornworm on a Tuesday evening while watering my tomatoes. A fat green caterpillar sat right on the main stem, surrounded by chewed-up leaves and dark droppings all over the soil below. My gut said to rip it off and crush it. But I'd read about parasitic wasps and took a closer look first. Sure enough, about twenty white cocoons dotted its back. I left it alone, and within two weeks I had a small army of tiny wasps patrolling my garden for future hornworms.
Those white cocoons belong to braconid wasps that laid their eggs inside the hornworm. The wasp larvae fed on the caterpillar's insides and then pushed through the skin to spin their cocoons. A parasitized hornworm is already dying and will stop feeding soon. Each cocoon holds one wasp that will hatch and go on to parasitize dozens more hornworms throughout the season. Taking away that one caterpillar wipes out a whole generation of free pest control for your garden.
Inspect the Caterpillar First
- Check the back: Look for white rice-shaped cocoons protruding from the skin, which indicate parasitic wasp activity inside the hornworm.
- If cocoons are present: Leave the hornworm alone and let the wasps complete their life cycle so they can defend your garden all season.
- If the back is clean: Proceed to remove the caterpillar right away before it causes more damage to your plants.
Remove Hornworm From Tomato Plant
- Grab and pull: Grip the caterpillar near the middle of its body and pull with steady pressure until the prolegs release from the stem.
- Drop in soapy water: Place the hornworm in a bucket of water mixed with dish soap to dispatch it quickly and humanely.
- Use gloves if needed: Wear garden gloves if you don't like the feel, but bare hands work fine since hornworms can't bite or sting.
Search for More Hornworms
- Follow the frass trail: Look for dark droppings on leaves and soil below, which point you toward hidden caterpillars feeding above.
- Check all nightshade plants: Inspect peppers, eggplant, and potatoes alongside your tomatoes since hornworms feed on the entire family.
- Hunt in the evening: Hornworms feed most during dusk and dawn, making these times the easiest for spotting them on your plants.
After clearing the current hornworms, start a routine of checking your plants every evening. A quick five-minute walk through your tomato patch at dusk catches new arrivals before they can do serious damage. Look for fresh leaf damage at the top of the plant first, since hornworms tend to start feeding there and work their way down.
One hornworm sighting almost always means more are hiding nearby. These caterpillars blend in with stems and foliage so well that you can stare right at one and miss it. Spray your plant with water from a hose and watch for movement, which makes them much easier to spot. These hornworm removal steps each evening keep your plants safe all season long. You can also remove hornworm from tomato plant branches up high by clipping the stem with pruners. Shake the cut branch into your soapy water bucket below.
Read the full article: Tomato Hornworm Guide for Gardeners
