If you have tomatoes in your garden, then chances are good at some point that you will encounter (cue scary music) “the dreaded” tomato hornworms.
That may have seemed dramatic, but they truly are a tomato grower’s horror show.
Tomatoes have a lot of enemies, but if you don’t catch most of them the first day it’s usually ok. Not so much with the tomato hornworm. They can decimate your tomato plants overnight.
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How To Get Rid Of Tomato Hornworms.
Chewed fruit, missing leaves, bare stems. What is happening to your tomatoes?!! It must be the dreaded tomato hornworm.
These garden bullies grow very fast. In fact, they can double in size every day! And it goes without saying, when you grow that fast, you will have a voracious appetite. And tomato hornworms LOVE tomatoes! They eat other garden vegetables too. Peppers, potatoes, and eggplants are host plants too, but tomatoes are their real preference.
Even though they are one of the largest caterpillars, It’s easy not to notice them because their green skin and markings blend in perfectly with your tomato plants. What really makes it hard is they like to hide on the underside of the large tomato leaves so you really have to look to find them, even though they are so big.
But all is not lost. Godzilla has not won. It may take some careful planning to get rid of these nasty garden pests and then keep them from attaching your precious tomatoes again next time around, but it can be done, and I’ll show you how.
What Are Tomato Hornworms?
The tomato hornworm (it’s really a caterpillar) is the larva of a large and beautiful hawk moth. It is also sometimes called hummingbird moths, or sphinx moths. The adult moth is huge, often reaching wingspans of 4-5 inches. (well that’s huge for a moth.)
It is a bright green caterpillar that grows to up to 5 inches long at full size. It has a spike or horn on its tail, giving this insect pest its name. It can be found throughout North America and Australia and has long wreaked havoc on tomato, pepper, tobacco, potato, and eggplant crops. (all nightshades)
What Do Tomato Hornworms Look Like?
Tomato hornworms are some of the biggest caterpillars you’re likely to find in your garden. They are bright green with around seven diagonal V-shapes along their sides. A black tail-like horn protrudes from the rear.
Their green color matches tomato leaves exactly, and their light striping helps them blend right in. They have a stubby green face with pointy claws for shoving food into their hungry little mouths. At full size, they are as big around as your finger.
There are two species of hornworms. The tomato hornworms and a close relative, the tobacco hornworm. It has a red-colored horn and diagonal white stripes instead of V-shapes but is otherwise identical. People get them confused all the time because they are so similar. And since both tomato and tobacco hornworms prey on the same plants, it really doesn’t matter which you have in your garden, you treat them the same way.
A hornworm in your garden is a hornworm. It has to be stopped! (cue the music again)
(If you notice, all the photos on this site are of the tobacco hornworm. I noticed all my photos of the worms in my garden and the ones my daughter took, were of the tobacco hornworm. So I looked at stock photos. Once again ALL tobacco hornworms….hmmm I guess the tomato hornworms are shy. 🙂 But in all honesty, they look very much the same.)
(This made me curious and I discovered that the tobacco hornworm is more common in the southern US and the tomato hornworm is more common in the northern US. But I’ll refer to them both as tomato hornworms.)
Related: 16 Top Secrets For Growing Great Tomatoes
How Do You Find The Tomato Hornworms?
Where do tomato hornworms go during the day?
It can be really hard to find these critters. During the day they hide under the large leaves of the tomato plant and they blend in perfectly, so how do you locate something you can’t see?
The easiest way to find them is by finding the damage that they do, which includes devouring whole leaves and smaller stems on the plant. They generally start by eating all the nice tender leaves at the top of a plant and sometimes leave holes in the side of the fruit.
As they become larger, the amount of defoliation increases.
You need to check for these caterpillars EVERY SINGLE DAY! If you let a week go by, your whole crop could be gone. Get eye level with them and look under the leaves. Run your hands over them too. They will thrash around if touched making them easier to spot.
Or you can spray the plant with water. Then stop and watch. The tomato hornworms will writhe and wriggle around and with a very keen eye, you will see their hiding place.
Follow The Poop
Another way to find them is by the green or black frass (poop) on the leaves or ground around the bottom of the plant.
Shine The Light
Since the hornworm is most active at night, one of the easiest ways to find these pesky hard to find critters is to shine a light on them. But not just any light. Go out at night, sit on the ground, and shine a UV flashlight on your tomato plants. Your worms glow under UV light. They look like bulbs on a Christmas tree. Then you can easily see to pick them off. (By the way, this works on scorpions too.)
If you find one hornworm, there are sure to be others so make sure to check your whole plant, and others around it, for more hornworms.
Will Tomato Hornworms Hurt You?
Nope! They look like they could poke you with their horn, but the truth is, it’s neither sharp nor poisonous. The only thing the caterpillar will do is grab hold of your finger with its many legs, which does feel pretty weird but doesn’t hurt. So grab right a hold of those suckers and yank them off your tomato plant. (they can hold on pretty tight)
Related: 6 Tips To Grow The First Ripe Tomato In Your Town
What do you do with hornworms you have picked off?
Should I kill tomato hornworm?
Like any garden pest you pull off your plants, you have a few choices of extermination. My favorite is to feed them to the chickens and ducks. This is a wonderful source of protein that is FREE!
If you don’t have chickens, you can drop them in a jar with water and a little dish soap. Or you can squish them. Be aware they make a real mess because they are very big.
My daughter can’t squish them between her fingers so she keeps two blocks of wood in the garden to use as squishing blocks. Set bug on block A and squish with block B. Whatever works for you. They have to die! (dun dun duuun)
Related: 12 Best Hot Weather Vegetables.
Should You Ever Let Tomato Hornworms Live?
After that last paragraph, you would think that my answer to that question would be NO. Kill them all!! But you would be wrong.
If you ever see a tomato hornworm with what looks like grains of rice on its back, leave it alone. Those are the eggs of a predatory insect, the braconid wasp. This is a good guy, a beneficial insect, and if you kill the hornworm, you kill the wasp eggs and the wasp babies that will hatch and eat the worm. The hornworm will continue eating however so you may decide to move it to a better location. Maybe a plant you don’t care as much about. (I know, I know they are all our babies.)
Also, understand, that I don’t think ALL hornworms should be wiped out. Bugs are very important to the ecosystem. These bad guys just don’t belong in my garden. I’m sure you agree.
The Hornworm Life Cycle
The tomato hornworm life cycle begins as the overwintering adults crawl out of the garden soil, starting in late spring or early summer. These moths then mate and lay eggs on the underside of the leaves of your vegetable plants. The tomato hornworm eggs are spherical and are whitish to light green in color.
In a few days, the tomato hornworm larvae hatch and begin eating and growing for the next 3-4 weeks.
When it is finished growing it will drop and burrow into the ground and pupate. This takes 2-4 weeks and then the moth crawls out of the soil again to start the process all over again.
At the end of the season, they overwinter in the soil and start again next spring.
Why is this important to know?
For one thing, you need to know that you are likely to have 2 to 3 rounds of fighting this caterpillar every season.
The second thing is to know that they pupate in the soil at the base of the tomato plant. …more about this later.
Keeping Tomato Hornworms Out Of The Garden.
It is so much better to use a combination of control and prevention methods to save your plants from hornworm damage than to try to keep up with them once they are already chewing away. Here are a few ways to win the battle against the green menace.
Related: How To Start A Vegetable Garden From Scratch.
Tilling your garden in the fall and spring.
I’m not a huge proponent of tilling your garden every year. I like to use the no-till method of gardening …most of the time. But this is a method that can be tried if you have a big hornworm problem. It is said to reduce your hornworm population by 90%!
Till the top two inches of your garden in the fall and allow the birds to access any worms or pupa on the surface. After two days, rake the soil again to expose any more that may have hatched, and after another day or two, plant a cover crop or mulch heavily.
As you rake through, pick out any you see, by hand.
Related: Should You Grow Determinate Or Indeterminate Tomatoes
I like to use organic methods whenever possible and beneficial insects fits that bill.
Beneficial predatory wasps are the single most important biological control gardeners have. These are a major form of tomato hornworm control. These wasps will lay their eggs inside or on top of the hornworm, and when the wasp larva hatch, they will devour the hornworm. (cue music again)
Trichogramma wasps and braconids are the most commonly available predatory wasps, and while they won’t harm humans or pets in any way, they love to eat garden pests!
Don’t worry. These do not sting people.
There are some companies that raise these insects and sell them to consumers. You can purchase these and release them into your garden or just plant lots of herbs and flowers that will attract them from your natural environment.
Ladybugs and lacewings are also helpful because they eat the hornworm eggs.
Remember, they are all very sensitive to any insecticide. If you use even the organic stuff you will be killing off the good guys too.
Floating Row Covers
One of the most effective means of tomato hornworm control is simply not allowing the moth to reach your plants in the first place. To do that, use floating row covers or high tunnels over your plants until they need to be removed for pollination. If they can’t reach your plants, they can’t lay their eggs.
Related: The Ultimate Beginning Vegetable Gardening Course.
Using black plastic mulch will prevent the moths from creeping their way to the surface. By keeping the moths in the ground, the cycle is interrupted, as the moths have nowhere to go and will eventually die before laying new eggs. Thick cardboard around your plants may work too and have the added benefit of discouraging weeds.
Solarizing the soil may be an option to try for a bad infestation.
Planting basil near tomatoes will improve the flavor of your tomatoes while at the same time repel tomato hornworms. Similarly, borage also repels the hornworms while attracting bees and other beneficial insects.
Other good choices are mustard, dill, yarrow, and parsley. Let these all go to flower to attract the good guys. Finally, marigold is a wonderful plant for all kinds of beneficial insects, including parasitic wasps, and its aroma tends to repel most caterpillars so they don’t move in.
Related: Growing Epic Tomatoes
Welcome the Birds
Do things to invite birds to the garden. Build birdhouses, put out bird feeders and birdbaths. They are natural predators to the tomato hornworms and will gladly give you a helping hand.
Letting your ducks and chickens into the garden at the end of the season will help rid your garden of overwintering hornworm eggs and pupa.
Rotating crops can also serve in reducing hornworm invasions. Although not the best prevention method, moving the crops each season can remove them from the pupae in the soil and make finding the crops a little harder for the hornworms. I have more information about crop rotation that I give to my email subscribers.
Although I haven’t personally tried this, dill is reported to be a favorite of Tomato Hornworms. Plant one near your tomatoes as a sacrificial plant. Let me know if you try this. I’d like to know if it really works.
If You Must Use Insecticide
Because we love the good guys, the beneficial insects, insecticides should be a last resort. Even organic insecticides have consequences. But if it is the difference between getting a crop to feed your family or not…
One of the best insecticides is diatomaceous earth sprinkled on the leaves and stems of your plants. Diatomaceous earth (DE) is harmless to humans and pets, (unless inhaled) but to all forms of caterpillars, it’s sharp like crawling over shards of glass and will cut up their tender bodies. It will cause hornworms, and all types of caterpillars, to dehydrate and die if they are sliced up often enough. It has to be reapplied after a rain.
DE is most effective on young hornworms while their skin is still tender.
You can also make a cayenne pepper and soap spray then spray it directly onto the leaves. The capsaicin in the peppers should make them drop from the plants.
As a very last resort, BT or Neem Oil can be used, but remember, these kill our precious beneficial insects too. They can even hurt the bees.
Learn More: Control Bugs In Your Garden, Naturally.
When tomato hornworm season starts, walk those rows daily. Don’t let that hungry little (little?) caterpillar cause you to have nightmares this year. Take immediate action. When facing the dreaded tomato hornworm, (duh, duh, duuuh) the best defense is a strong offense.
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19 thoughts on “Simple Ways To Get Rid Of Tomato Hornworms”
I planted dill in my garden to attract butterflies, went out yesterday and saw about 6 hornworms. I have some tomatoes right next to them and they,so far, have stayed on the dill🙏
Woo Hoo! It’s working!
I use spinosad soap, I have had every type of worm you can think of this year. Sprayed spinosad soap and all worms gone. And it’s organic.
I’m glad it worked! You just need to be careful that you don’t kill off all your pollinators and beneficials at the same time.
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We have two tobacco hornworms in our classroom right now so we can get video of how fast they actually destroy foliage, and may add some soil and film the complete metamorphasis.
Smashing/grinding hornworms into paste, putting into a spray bottle with water, and spraying down the plants/surrounding area will prevent Sphinx moths from even approaching, let alone lay eggs. They can sense the “mass deaths of their own” and avoid the area all together.
Since tomato leaves used to make Sun-Tea (don’t steep over 24 hours…the smell is almost as bad as Erwinia) are an effective ‘organic’ control of aphids and some other soft-bodied pest/pathogens, I hypothesized to the class that hornworm frass would be a concentrated version of that similar to an extract, and would probably be more effective/concentrated…so that is something we set up a proper lab experiment to control all variables for later.
That sounds so interesting. I’d love to hear your results.
Do you brush the frass of the plant and leave it as fertilizer or do you clean it up?
I never pay any attention to the frass once the worm is gone. The only reason to brush it off is to make sure you have all the worms. (if you see more the next day…hunt again)
Thank you for growing my garden knowledge…xoxoxoxo
Thanks! Glad it helps.
Is there a way to feed them so you can enjoy the moths without involving the tomato plants?
Not that I’m aware of.
Do you have any advice on keeping the bugs and worms off of ears of corn?
I’m still working on that one. I’ve heard you can add oil to the top of the ear after it silks, but the worms always get my corn before it silks, so it doesn’t work for me. I do have more luck growing mine in the fall rather than the summer, though. If you can figure out the timing in your area it will help a lot.
Wow! Thank you so much for writing this incredible resource. I love how detailed and thorough you are…super helpful!! I have only had tomato hornworms in my garden once but once was DEFINITELY enough. Now, when I plant tomatoes and peppers, I make a “paper collar” around the base of the plant and the grubs can no longer climb onto the host plant to begin with. No more hornworms. It’s kinda magical!! Again thanks for this awesome post! Love your blog!
So glad you like it. The collar is a great suggestion. Love your blog by the way 🙂