Identifying the Caterpillars Eating Your Tomatoes

Updated on April 12, 2017

Tomato Caterpillars—What Are They?

Do you have big green caterpillars on your tomato plants? That's a sure sign that your garden is playing unwilling host to one of the most common tomato pests in North America, the hornworm caterpillar.

The scientific name for these big boys is Manduca quinquemaculata, and they are the larval form of a big brown moth known as a "hawkmoth" for its powerful, swooping flight. Chances are good that you will never encounter the moth, since it hides during the day and is pretty inconspicuous despite its size.

But if you grow tomatoes, you are almost certainly familiar with its immature forms. Read on for some information and advice about what to do with those big green caterpillars!

How to Get Rid of Tomato Caterpillars

  1. By hand.
  2. With poison.
  3. Via organic solutions.

Scroll down to learn everything you need to know in order to identify those tomato-eaters and get them out of your garden.

How to Identify a Hornworm Caterpillar

  • Usually pale leaf green in color, but sometimes black
  • Seven V-shaped white stripes along the side
  • Eight black and yellow spiracles on each side of the body (look like eyes)
  • Dark blue or black horn on its tail
  • Grow as large as 4 inches long
  • You'll probably find them near tomato, pepper, or eggplant, since that's what they like to eat.

How Can I Tell if Caterpillars Are Eating My Tomatoes?

  1. First, examine your plants. The first sign of a caterpillar infestation is missing leaves. These guys can eat a leaf right down to the stem, and if enough of them attack a plant they can turn it into a cluster of bare green stems and stalks. It's probably the big green larva of the hawkmoth, and once you have them, it can be hard to get rid of them.
  2. Then check for young tomatoes and leaves that have been partly (or completely) eaten. If you have leaves with big chunks missing, and baby tomatoes with even bigger chunks eaten away, you probably have hornworms in your garden.
  3. If your eyes are sharp and you do find one munching away on a leaf, don't stop! Keep looking—where there is one, there is almost certainly a whole bunch more close by.
  4. Check the undersides of the lowest branches, near the main stalk. They like to hide there.
  5. If you still don't see evidence, have a look around the ground under your plants. You are looking for poop, and these big caterpillars make big poops. They look a little like tiny hand-grenades. A pile of these under a tomato plant means someone up above is doing some serious eating.

Even when you know what you're looking for, these big caterpillars can be hard to find. They are unbelievably well-camouflaged on the bright green leaves, and the little slanted marks on their sides blends perfectly with the angled veins of the tomato plant leaves. So when you look, you may find some, but you may not—they are truly well-adapted to evade discovery by predators, which you are now.

Tomato Hornworm and Damage
Tomato Hornworm and Damage | Source

So You've Identified Your Caterpillars as Tomato Hornworms—Now What?

Let's say you do find a few fat green hornworms gobbling up your tomatoes. Now it's time to deal with the problem. You may simply decide to live and let live, and really, unless you rely on your tomatoes to survive, why not share the wealth a little? Hornworms will eat a few but overall they are usually not a huge problem, much less serious than aphids or disease. Also, the birds who would usually peck away at your tomatoes will fill up on fat green caterpillars instead. Consider making them part of an educational experience. They are pretty easy to raise—they eat tomatoes, duh—and after they pupate, they turn into big brown moths, which is pretty cool if you have kids. So don't just assume that your hornworm problem is real ALL that serious. Has anyone ever said, "wow, I really don't have enough tomatoes from my garden this year"?

But okay, let's say you want those hornworms gone. Here are a few options.

How to Get Rid of Tomato Caterpillars

Method #1: By Hand

The first method to eliminate them is to physically pick them off the plant. This is labor-intensive, but work like this is, I believe, the reason that children were invented. Children and pocket change: offer the neighborhood scamps a dime for every hornworm corpse they bring to you, and there's a pretty good chance your caterpillar problem will be over. You might be down a few dollars, but it's a better deal than paying for store-bought insecticide that may or may not work.

The drawback to this method is the same reason that hornworms and other prey insects are not extinct: it's really impossible to kill every member of a population, unless you also destroy their habitat (predator animals don't do that, while humans are sadly very good at). So yes, some caterpillars will survive and keep munching on your plants. But the problem will be a lot less serious—maybe you could even live with it?

Method #2: Organic Solutions

The half-way step between removing them with your bare hands and plain old poison is insect soap or dust. There are several recipes for this online, and they usually affordable and generally fairly effective. They work by blocking the spiracles (the holes along the side of the body that the insect uses to breathe).

Diatomaceous earth will do the trick. Again, this method will not kill all of the caterpillars, but will knock out enough to leave you with a healthy tomato harvest at the end of the summer.

Another product that I have used with success is pure cedar oil. It's safe, effective, and it smells good too! It's been used as an insect repellant for eons. If you're determined not to use chemical insecticides, cedar oil may well be an answer for you.

Ladybugs, green lacewings, and common wasps are its natural predators. They can also be reduced by planting marigold close by.

Method #3: Poison

Okay, if you must, there are compounds available at the hardware store or garden center that may kill off your tomato hornworm population for good. You can research these on your own. There are various kinds and substances on the market, and they all claim to be safe, and maybe they are, but they can't be as safe as paying a bunch of kids pocket change to pick caterpillars off your plants is.

To Poison or Not to Poison?

Would you ever decide to use poison or chemicals to control tomato hornworms?

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Are Hornworm Caterpillars Dangerous?

Although the tomato hornworm does have what looks like a stinger coming out of its tail, it's completely harmless. There are some other species, though, that are venomous and can give you a pretty nasty sting if you touch them or brush up against them.

Learn how to identify these stinging caterpillars at Guide to Stinging Caterpillars of North America.

What's Up With the Horn?

The curved tail or horn on the hornworms's rump is not a stinger, though scientists think it may look enough like one to provide protection to the caterpillar. There is no sting, or even a sharp tip to the horn, so its use as a protective device is debatable. It has also been suggested that the tail resembles a snake's tongue, or that it draws attention to the back end, sparing the head of the insect from attack.

Questions & Answers

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      • profile image

        Phil 4 days ago

        Moths lay their eggs UNDER the leaf of the tomato plants and they is why you do not see them until they have begun chewing your tomato plants to death. These litle green base tards double in size every other day, so you need to keep an eye on your tomato plants every day. I cure my problem by covering my tomato plants with some fine mesh fbaric that allows light, air and water to penetrate the material. It cost a few bucks but I cannot watch my garden 24/7 and if you buy a decent fabric it will last a few years so you can sue it over and over again. I garden organically but I do not see the point of spraying neem or orange oil on my plants all the time especially since it rains often here in the Houston area. The fine mesh netting does it all for me and tomatoes are self pollinating so you don't have to worry about that. However, I have increased my yield once the flowers appear I will take an old electric toothbrush and brush on the top of the flowers to simulate a bee and the pollen will drop and help set fruit. I do this either early in the morning or at sunset. You can also shake or thumb the leaves to loosn the pollen but the tooth brush is more useful and doesn't knock the flowers off.

      • profile image

        Chris Grina 7 months ago

        Every time I grow tomatoes, the horn worms seem to appear out of nowhere, now they are in my that normal?

      • profile image

        Judith Maier 7 months ago

        My deck is about 15 feet off the ground. I have several tomato plants in pots. I had these droppings on my deck which looked like little pellets just below one of the plants. I would wash the deck down every morning and then they would reappear the next day. Today the droppings happened while we were right there and one of our guests spotted the caterpillar. It was unbelievable the way that it blended right into the plant. This guy was pretty big. Should I expect more? Your article was a big help in identifying this caterpillar.

      • profile image

        Gaia 7 months ago

        Thanx for article!

        What to do with those tomatoes that just had worm eggs on them and after washing there are spots on them where eggs where?But otherwise tomato looks decent.Can I eat such tomato?

      • profile image

        Jean Bailey 7 months ago

        I think that I found a tomato hornworm on a leaf of one of my pepper plants this morning. It was covered with small white oval attachments that from your article are probably wasp eggs. I took pictures but I guess I cant post them. I would like to be able to verify my find but since the damage to a few of my tomatoes is as pictured here I have to assume that is what I have.

      • profile image

        TinaHutto 8 months ago

        Luckily I haven't had a problem with the tomato hornedworm this year but I have little black worms this year with a yellowish stripe..anyone know what kind of worm it is and how to wipe it out before it wipes out my crop?

      • profile image

        Marlane Renner 8 months ago

        I have marigold plants in a container right next to the container tomato plants, and guess what? I've got the hornworm caterpillars! They are beautiful, but boy, do they like to eat!

      • profile image

        Nina 8 months ago

        They already ate all of my tomato plants...I only had 2 of them. So I guess they get to live.

      • profile image

        Theresa 19 months ago

        The eggs are wasp eggs. when they hatch they will kill the caterpillar. They are a natural way to get rid of them.

      • profile image

        erinbliss 19 months ago

        OMG, just found one this morning! AND it has eggs hanging off it like crazy. In fact the eggs are how I found it. I wish I could post a photo.

      • profile image

        joe 19 months ago

        Wasp eggs. They eat the worms.

      • profile image

        tina 20 months ago

        what are those little white things. Eggs!!!

      • profile image

        Don Cooper, DC 20 months ago

        Simply plant marigolds near your tomatoes. Presto! No horn worms will appear.

      • profile image

        George 20 months ago

        I was going to blame the dozen or so squirrels for munching my few tomatoes for moisture until I discovered the beautiful hornworm. Your suggestions are great. Thanks

      • Pamela Kinnaird W profile image

        Pamela Kinnaird W 3 years ago from Maui and Arizona

        Great hub you've done here and you're braver than me -- using close-ups of these critters. I couldn't use close-up photos. Voting way up and sharing. T'is the season for the critters.

      • profile image

        Susan 4 years ago

        My Hornworms are feeding on the poisonous Angel Trumpet plant. Holy moly, how toxic are these moths going to be to anything that eats them.

      • Esmeowl12 profile image

        Cindy A. Johnson 4 years ago from Sevierville, TN

        I encountered my first ever tomato hornworm today and was thankful for your hub for more information. While certainly destructive, the caterpillar is quite beautiful. Thanks for enlightening me!

      • profile image

        Sharfire 5 years ago

        I'm going to try the water, dish soap, baking soda and cayenne pepper spray and see if this will turn off those caterpillars.