Tomato hornworms can strip a tomato plant of its leaves in just a few days. Learn how to identify tomato hornworms and tobacco hornworms, spot the signs of damage, locate them, and protect your tomato plants using companion planting, beneficial insects, and other organic gardening methods.
Tomato Hornworms: What to Do When They Show Up in Your Garden
If you've been gardening for any length of time, you've probably seen a tomato hornworm. And if you've seen one, you probably remember it. These things are enormous, bright green, perfectly camouflaged, and somehow invisible until they've eaten half your plant.
They’re the stuff of nightmares!
The Year I Retired My Garden Tongs
I used to find them every single season: big fat tomato hornworms, which meant they'd been out there eating my plants for a while before I spotted them.
I don't know about you, but I can't pick them off the plants with my bare hands. I wear gloves. In fact, for a while I kept a pair of kitchen tongs in the garden specifically for hornworm removal.
If you've ever tried to pull one of these off a tomato stem, you know they do not let go without a fight. And they’re so squishy.
But last summer I found just two small hornworms. The year before that, zero. Keep reading for my hornworm prevention secrets.
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What are hornworms?
The tomato hornworm is the caterpillar of the five-spotted hawk moth.
But there's actually a second species as well - the tobacco hornworm - and it's the caterpillar of the Carolina sphinx moth.
.jpg "Whether you find tomato hornworms or tobacco hornworms on your tomato plants, the process of controlling them is the same. Here's what to do to prevent damage and the loss of your plants.") |
| Tobacco hornworm |
The two look almost identical, and most gardeners - myself included, honestly - have probably been calling whichever one they found a "tomato hornworm" without knowing the difference.
Both tomato hornworms and tobacco hornworms target crops in the nightshade family, including:
- Tomatoes
- Peppers
- Eggplant
- Potatoes
- And yes—tobacco plants
The easiest way to tell the two species apart is by their stripes.
Tomato hornworms have white V-shaped markings along their sides. Tobacco hornworms have diagonal white stripes. And the horn is different too: red-orange on the tobacco hornworm, and dark blue-green on the tomato hornworm.
Although I've called them tomato hornworms, what I've been finding all these years have actually been tobacco hornworms.
They both eat your tomato plants, they're both found the same way, and you deal with them the same way. So for our purposes today, we're treating them as one problem.
You may have seen these big brown moths hovering around your garden flowers and thought you were watching a hummingbird - they're big moths, they move fast, and they hover the same way hummingbirds do. But that's the moth that's laying eggs on your tomato plants.
And here’s the interesting twist: while the caterpillars can do a lot of damage, the adult moths are good pollinators, especially for nighttime pollination.
If you're growing tomatoes this year, grab my free one-page Tomato Growing Guide. You'll find quick-reference information on companion planting, hornworms, fertilizing, trellising, blossom end rot, and other common tomato-growing questions. Download your copy here.
How to find hornworms on your tomato plants
How do you know you have a hornworm problem?
The first clue isn't the caterpillar itself - it's the damage they leave behind. If the leaves at the top of your tomato plant look like something's been eating them, something has been eating them. Hornworms eat the leaves right off the stems, leaving them bare.
The second clue is the droppings. Hornworm frass - the polite word for caterpillar poop - is distinctive: dark, and shaped almost like little grenades. If you see frass on the leaves or on the ground below your plant, the caterpillar is usually somewhere above them. Look on the branches above.
And then there's my favorite trick, although you might feel a little ridiculous until it works: go out at night with a blacklight flashlight. Hornworms glow under UV light, and you'll be able to spot them easily when you couldn't find them in broad daylight. I love this method, and so does my grandson!
While I believe in working with nature, encouraging beneficial insects, and not rushing to wipe out every pest in the garden, I also have a line.
And for me, hornworms are really close to that line. Because they don't just nibble, they can strip a tomato plant almost overnight.
So this is where I take a balanced approach. I don't try to eliminate every caterpillar or every moth from my garden. Those moths - even the ones that lay hornworm eggs - are pollinators. They have a role to play.
But when it comes to large, destructive pests like hornworms, I focus on control, not coexistence.
That means I check my plants regularly, I remove hornworms when I find them, and I let nature help me where possible, with beneficial insects, birds, and a few well-chosen companion plants.
Because balance doesn't mean letting pests take over. It means not overreacting. It also means not ignoring the problem.
A few holes in your leaves? That's part of gardening. A plant being defoliated? It’s time for an intervention!
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| Tomato hornworm. Image credit: Whitney Cranshaw, Colorado State University, Bugwood.org |
What to do when you find hornworms
So you've found a hornworm - or maybe six of them. Now what?
First, you need to get the caterpillar off of the plant. Use gloves if you have to. (For a long time I kept a pair of kitchen tongs in the garden specifically for hornworm duty!)
They hold on tight to the plant stem, by the way. Don't just yank; work them loose gently or you'll damage the stem of your plant.
Once you get it off the plant, you have several options.
- If you have chickens, this is their lucky day. Hornworms are apparently a delicacy. Toss it in the coop and enjoy the show.
- If you fish, this is your lucky day. Bass, bluegill, and catfish go crazy for these things. They're big, soft-bodied, and they wiggle, which is apparently irresistible to fish.
- If neither of these applies to you, the simplest method is to drop them into a jar of soapy water, put the lid on, and move on to your next task.
Yes, you can move hornworms to a "sacrificial plant" on the other side of your yard instead of doing away with them. I appreciate the idea in theory. But honestly, they’ll decimate that plant and move back to your garden in my opinion. So it’s your call.
Hornworms and parasitic wasps
If you come across a hornworm that has little white, rice-like capsules stuck all over its back, leave it on your plant. Here’s why:
You might think those are eggs, but they’re not: they’re actually cocoons from braconid wasps.
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| Parasitic wasp cocoons on a hornworm. Don't destroy this one! Image credit: R.J. Reynolds Tobacco Company, R.J. Reynolds Tobacco Company, Bugwood.org |
The adult wasp lays her eggs inside the hornworm. The larvae hatch inside the caterpillar and feed on it from the inside out.
When the larvae are ready, they emerge and spin those white cocoons on the outside of the caterpillar.
So as unpleasant as that sounds, that hornworm is the “walking dead,” and you should leave it in your garden, because the baby wasps in those cocoons will go on to control more hornworms for you when they’re adults.
Preventing hornworms: Companion planting
So how did I go from finding a horde of hornworms every single summer to finding two in an entire year?
Honestly, I think it comes down to what's growing around my tomatoes. Back then I planted one bed with tomatoes, another bed with lettuce, and another with cabbage, and so on.
Nowadays my beds look rather chaotic. I plant some of this and some of that and a few of those in each bed. No more monoculture raised beds for me, I grow in “neighborhoods,” planting certain groups of plants together.
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| Marigolds are another companion plant for tomato plants. |
This is known as companion planting. While it’s not an exact science, my own experience has made a believer out of me.
When I started planting certain things near my tomatoes, the hornworm problem largely went away. I can't prove that’s the reason, but the timing sure points to it. I know what my garden looked like before and what it looks like now.
The theory is that these plants either repel the moths before they lay eggs, or attract beneficial insects that take care of the problem for you, like those braconid wasps. Maybe they do both. Either way, my tomatoes are happier and I've retired the tongs I used to keep in the garden.
The plants I keep near my tomatoes are lemon balm, borage, marigolds, and basil. These plants give off a strong scent that might actually help repel tomato hornworms and other pests.
Dill and parsley are both good to include too, not because they directly repel hornworms, but because they attract the right kind of insects - like parasitic wasps - that help keep hornworm populations down.
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| Dill growing next to tomato plants |
Calendula is another hornworm-fighter. Their daisy-like flowers attract pollinators and beneficial insects like ladybugs and lacewings, but it also draws in parasitic wasps that prey on tomato hornworms.
These plants aren't exotic or hard to find. You can find most of them at any garden center, and some you can start easily from seed.
As a last resort, try Bt-K
If you feel you need even more help conquering the hornworm army, you might want to use Bt-K, a soil bacterium that targets and kills caterpillars, and is rated safe for organic gardens.
The trouble is that BT doesn’t know the difference between bad and good caterpillars, such as swallowtail butterfly caterpillars. (They'll eat the dill and parsley you might plant near your tomato plants, but honestly, I plant extra dill just for them. Dill isn't as important to me as tomatoes are, and the butterflies are so beautiful.)
If you're growing tomatoes this year, grab my free one-page Tomato Growing Guide. You'll find quick-reference information on companion planting, hornworms, fertilizing, trellising, blossom end rot, and other common tomato-growing questions. Download your copy here.
Protecting your tomato harvest
Tomato and tobacco hornworms are garden pests that feel overwhelming the first time you encounter them - partly because they're so big, and partly because by the time you find them, they've usually already done some damage.
But once you know what to look for, they're very manageable:
- Keep an eye on your plants. Observation is your best first line of defense.
- Check the tops of your plants for missing leaves and bare stems.
- Look for those little grenade-shaped droppings, known as "frass."
- Grab a blacklight flashlight and take a walk through the garden after dark. It's actually kind of fun once you get over the part where you're hunting caterpillars in the dark.
And if you want to get ahead of the problem before it starts, think about what you're planting near your tomatoes. Lemon balm, borage, marigolds, basil, dill and parsley are simple additions that have made a real difference in my garden.
.jpg "Borage is a good companion plant for tomatoes, and is thought to deter insect pests such as hornworms.") |
| Borage plant |
Tomatoes are the reason I started gardening all those years ago, and maybe they're your reason too. Those plants are worth protecting. And once you know what to look for, hornworms go from being a garden nightmare to just another problem you know how to solve.
Download your FREE Tomato Growing Guide here.
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Kathi Rodgers is the gardener and writer behind Oak Hill Homestead (est. 2006) and the host of HOMEGROWN: Your Backyard Garden Podcast. With over 30 years of gardening experience in a variety of climates and soils, she helps new and aspiring gardeners grow healthy, organic food right in their own backyards.
A passionate advocate for simple, self-reliant living, Kathi is the author of multiple ebooks, a published magazine contributor, and shares practical advice with readers who want real-life solutions they can trust.
Kathi lives in Oklahoma, where she grows more cherry tomatoes than she can count and keeps a watchful eye on tornado season. A proud grandma and great-grandma, she believes that wisdom - like a bountiful garden harvest - should be shared.
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