If you’re out in your vegetable garden and see big, honking caterpillars like this, you need to remove them from your tomato plants as quickly as possible. These are hornworms and they can be very devesatting to your tomato plants. There are two main hornworm that tend to show up on our tomato plants: the tomato hornworm and the tobacco hornworm.
On the back side of the caterpillar, you’ll see a horn—that’s where it gets its name. The tobacco hornworm has a red horn, while the tomato hornworm’s horn is blue. The tomato hornworm also has a V-shaped pattern on its sides instead of stripes. Either way, both kinds are very damaging and need to be removed from your tomato plants.
Companion Plants Can Help
There are a couple of ways to prevent them. I like to plant basil as a companion plant all over my garden. It tends to mask the tomato plants and make them harder to find for the moth to lay it’s eggs on. In the garden bed where these hornworms showed up, that didn’t help because I planted parsley instead. I really like the idea of companion planting, and when I plant enough basil around everything, the hornworms usually have a hard time finding the tomato plants. Planting basil is usually my first line of defense against hornworms.
Organic Sprays
Another option is to spray with a product called Bt (Bacillus thuringiensis) (aff). It’s a bacteria that’s safe for organic gardening. The caterpillars eat it, and it destroys them from the inside. This is only effective on the larval stage of insects that actually eat the plants. Bt can be used on squash also to prevent the squash vine borers.
If you don’t catch the hornworms yourself, sometimes parasitic wasps will do the job. They lay their eggs in the caterpillars, effectively killing them from the inside out as part of their reproductive cycle.
If you see something that looks like little grains of rice coming out of the back of a hornworm, that means parasitic wasps have already taken care of it. In that case, leave it alone—nature is doing the work for you. But the ones I found this morning are still alive and moving, so I’m going to get them out of the garden completely. Plant plants like dill, fennel, or yarrow nearby to help attract these beneficial wasps!
If you raise chickens or other fowl, you can feed the hornworms to them—they’ll love the juicy treat.
How I Found the Hornworms
I first noticed some damage a day or two ago. It looked like the tips of my tomato plants had been clipped. At first, I thought it was deer since we have a lot in the area, but this plant is in the middle of the vegetable garden. If it were deer, they would’ve eaten much more and gone down to the nubs of the plant. Then I thought maybe rabbits. But as I investigated, I figured it was probably caterpillars. Sure enough, I came out the next morning and found two on the cherry tomato plant. I haven’t seen any others, but I’ll continue to give the garden a good inspection just to be sure and stay on top of things.
The first sign of a hornworm that you will usually notice is usually missing vegetation. The caterpillars are camoflauged and blend in so well with the plant that they’re hard to see. Some gardeners use a black light after dark which can make seeing them a lot easier. The caterpillars glow under black light, making them easier to spot. I haven’t tried that myself—I usually just pick them off when I find them.
Hornworms can do a lot of damage. What you see in this video is about one day’s worth of destruction by just two hornworms.
Eventually, these hornworms turn into sphinx moths, which are really cool-looking creatures. If you’d prefer not to kill them outright, you can move them. Clip a bit of the tomato plant they’re on and relocate them far away from your garden, where they won’t cause further harm.
You definitely don’t want these guys going to town on your tomatoes. They’ll also attack other solanum family plants like peppers and tomatillos—but tomatoes are their favorite, and they’ll chow them down fast. So get them out of there as soon as you can!
Signs of a Hornworm Infestation
- Chewed or Missing Leaves – Large sections of leaves suddenly disappearing, especially near the top of the plant.
- Bare Stems – Stems stripped of foliage, often leaving just the veins or stalks.
- Hornworm Droppings (Frass) – Dark green or black pellet-like poop on leaves or the ground beneath the plant.
- Partially Eaten Fruit – Tomato fruits with bite marks or chunks missing.
- Camouflaged Caterpillars – Large green caterpillars that blend in well with the plant—look along the stems and undersides of leaves.
- Wilted or Damaged Growth Tips – New growth may look wilted or chewed down.
Ways to Deal with Hornworms
- Hand-Picking
- The simplest and most effective method. Look for hornworms in the morning or evening when they’re most active. Drop them into a bucket of soapy water—or feed them to chickens if you have them.
- Use Bacillus thuringiensis (Bt)
- A natural bacteria-based pesticide safe for organic gardening. Spray Bt on the leaves; hornworms eat it and die within a few days. Most effective on smaller caterpillars.
- Attract Parasitic Wasps
- These beneficial insects lay eggs inside hornworms. The larvae feed on the hornworm and eventually kill it. You can encourage them by planting flowers like dill, fennel, and yarrow.
- Companion Planting
- Plant basil, marigolds, or dill near tomatoes. Some gardeners report that hornworms avoid areas with these strong-scented plants.
- Use a Black Light at Night
- Hornworms fluoresce under black light. Head out after dark with a UV flashlight to spot and remove them more easily.
- Encourage Predators
- Birds, predatory insects, and even toads will eat hornworms. A diverse, pesticide-free garden attracts more of these natural helpers.
- Remove Eggs (if spotted early)
- Hornworm moths lay small, pearl-colored eggs on the undersides of leaves. Check regularly and rub them off to prevent an outbreak.
- Neem Oil (Caution)
- Some gardeners use neem oil, but it may not be very effective on hornworms and can harm beneficial insects. Use with care.
- Relocate Instead of Kill (Optional)
- If you don’t want to kill them, clip off the stem they’re on and move them far away from your garden.
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