Tomato Hornworms

How to Identify and Get Rid of Tomato Hornworms

Tomato Hornworm
Amanda Hill

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Big, fat, and green! Here are tips on how to identify, control, and get rid of tomato hornworms in your garden.

What Are Hornworms?

If you’ve ever grown tomatoes, chances are good that you’ve dealt with these green caterpillar pests. There are two main garden pest species, tomato hornworms and tobacco hornworms, which can be found in most regions of the U.S. and in southern Canada. Both species can ruin your tomato crop in record time! They also feed on other plants in the Solanaceae (nightshade) family: eggplants, peppers, tobacco, and potatoes. They blend in quite easily with the green foliage and feed non-stop, creating spotty and chewed leaves and fruit.

Tomato (and tobacco) hornworms live according to the following life cycle:

  • In late spring, large adult moths lay eggs on the undersides of foliage, which will hatch within a week. The adult moths are easily recognizable; they’re commonly called sphinx or hummingbird moths.
  • Caterpillar larvae will hatch in late spring and feed for 4–6 weeks before creating a cocoon, overwintering in their pupal state in the soil. If the weather is warm enough, larvae may only burrow for as little as 2–3 weeks.
  • Moths will emerge in the spring, and will then lay eggs once again. More than one generation a year may be possible in warmer climates.

Tomato hornworm moth (female). Photo by Didier Descouens.
Tomato hornworm moth (female). Look out for the moths in late spring. Photo by Didier Descouens/Wikimedia Commons.

Identification

How to Identify Tomato Hornworms

Hornworms can be up to 5 inches long—which can be quite a shock when you first come across one! They do the most damage in the caterpillar—or larval—stage. They are pale green with white and black markings, plus a horn-like protrusion stemming from their rear. (Don’t worry, they aren’t able to sting or bite!) The caterpillar also has eight V-shaped stripes on its green body. Tomato hornworms come from a mottled brown-gray moth (see picture, above). 

    The larvae blend in really well with the plant greenery. Just get used to a daily patrol, looking for hornworm eggs and small caterpillars. Here are some cues of infestations:

    • Hornworms tend to start feeding from the top of the plant; look for chewed or missing leaves.
    • Look closely at the TOP of your tomato leaves for dark green or black droppings left by the larvae feeding on the leaves. Then look at the underside of leaves and you’ll likely find a hornworm.
    • Look for stems missing some leaves and wilted leaves hanging down. You may find white cocoons and their hornworm hosts nearby.

    Tomato Hornworm. Photo by Amanda Hill.
    Tomato hornworm

    Tomato vs. Tobacco Hornworms

    There are a few species of hornworms that inhabit North American gardens, including tomato hornworms (Manduca quinquemaculata) and tobacco hornworms (Manduca sexta). Both species feed on common garden plants like tomatoes, potatoes, peppers, and eggplants. Here’s how to tell which caterpillar is which:

    • Tobacco hornworms have parallel white stripes; tomato hornworms have white V–shaped markings.
    • Tobacco hornworms have black spots lining each of their stripes; tomato hornworms do not.
    • Tobacco hornworms have a red “horn” on their tail end; tomato hornworms have a black horn.

    tomato-worms-hornworms.jpg
    Can you tell which hornworm this is? (It’s a tobacco hornworm! Notice the white stripes with dotted black lines and a red “horn.”) 

    Tomato Hornworm Damage

    If you see leaves with large holes and severe defoliation, devoured flowers, and/or scarring on fruit surfaces, you might have tomato or tobacco hornworms. The fruit also may be damaged by sunscald because of the reduced foliage cover.

    Control and Prevention

    How to Get Rid of Tomato Hornworms

    • Handpicking is an excellent tactic for control if you have the time and patience, or a small garden. The caterpillars are not dangerous and can neither sting nor bite. If you are squeamish about crushing these large insects, drop them into soapy water instead (or feed them to your chickens, if you’ve got a flock).
    • If the hornworm population or the area of your garden is too large, insecticides can be effective, though they should be a last resort. You can use the organic pesticide Bt (Bacillus thuringiensis), which is a bacterium that acts as a stomach poison on some larval insects (but doesn’t harm other plants or animals). Bt must be ingested by the caterpillars to be effective, and it must be reapplied to plant foliage after rain. Please check with your local Cooperative Extension for a list of approved insecticides in your area.
    • Insecticidal soaps will also kill hornworms, but the pests need to come into direct contact with the substance.

    get-rid-of-hornworms.jpg
    A tobacco hornworm covered with parasitic wasp eggs. 

    How to Prevent Tomato Hornworms

    • Till soil at the beginning and end of each gardening season to destroy overwintering larvae. Tillage has shown to cause up to 90% mortality.
    • Keep wasps around; a number of species are beneficial insects which feed on hornworms and act as a biological control. You may see hormworms with parasitic wasp larvae attached, which look like grains of rice (see picture, above). These attacked hornworms will continue to feed for a little while, but will soon succumb to their hitchhikers, so it’s wise to leave them alone and let the wasps carry out their life cycle. Alternatively, remove infected hornworms and place them far away from your garden. This way, the wasps will still do their job, but the hornworm won’t continue to damage your crops. 
    • Other beneficial insect, like ladybugs and green lacewings, may feed on young hornworms or hornworm eggs.
    • To keep hornworms away from your tomato plants next year, try interplanting dill or basil; marigolds are also an excellent companion plant.

    See the Almanac Garden Pest and Disease Library for more information on common pest problems.

    Reader Comments

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    Used Dawn dish soap diluted

    Used Dawn dish soap diluted in sprayer, also Hot Chili Sauce, garlic mix it didn't faze them! Can't use Neem Oil due to the heat. Going to try BT.
    Thanks

    I read a few articles last

    I read a few articles last year regarding the use of hot peppers, garlic and water, that you spray on plants to keep such as aphids, hornworms, etc, away. I can tell you that it was not only messy, but it didn't work. I tried everything except for bt, which I've read about this year. I tried sevin dust but for some reason it made the leaves of my tomatoes turn very hard . I had 7 tomato plants last year and the few tomatoes that I had were very small and not good.
    I had 2 square foot gardens, that I grew okra, eggplant, beets, peas, zucchini, jalapeños, Lima beans, radish, green beans, bell pepper, and cow peas, which all yielded a great crop. I also grew pickling cucumbers on the east side of my house that also did extremely well. I did have a problem with aphids, and read that neem oil worked well, but for me after it got hot, it killed a few of my plants. I live in the Southern Central Valley of California, and the summer temperature easily tops 100+ degrees sometimes a month or more straight. It was 112 degrees just two days ago. So I've got to be careful what I use on my plants.
    I planted pickling cucumbers again in the same spot as last year. I noticed that the leaves were being eaten rather quickly, so I researched the Web, most site's either said that it was slugs or a beetle. I put down slug bait, and the next morning, I noticed that more leaves were eaten. I went through the plants, turning the leaves over to find a slew of hornworms noshing away on my cucumbers.
    I haven't found anything yet that's worked without harming the plants, other than inspecting and picking off the hornworms by hand. I will be definitely looking into BT as a remedy. It is a cornstarch based bacteria, once the hornworms eat it, it will paralyze the stomach and they die. Its also approved for organic gardening. I hope that this helps you.
    Good luck with your garden.

    I haven't found any big green

    I haven't found any big green worms. Just little fuzzy ones eating holes in the tomato leaves. The leaves look like swiss cheese. Are these the baby horn worms? Is there any way to get ride of them before they turn into the big worms and destroy the fruit and the plant? They are all tiny and fuzzy and black and white, about 1/4 inch at most right now.

    Another of nature's

    Another of nature's mysteries: It sounds like you have tomato fruitworm, which will soon become a moth...but we can't be sure.
    Yes, they could destroy the plant, esp the fruit. If it's the fruitworm, some sources recommend Trichogramma spp. egg parasites; the larval parasite Hyposoter exiguae; and predators such as bigeyed bug and minute pirate bug. (The idea is, fight nature with nature.) However, some even advise using organically acceptable Bt (consult your local extension or nursery). In the meantime, pick them off and eliminate them.

    a friend told me she heard

    a friend told me she heard that putting pennies around the base of your plants will stop the worms from crawling up the stalks, something about the copper in the penny they dont like, will this not harm my plants?

    Many gardeners say copper

    Many gardeners say copper pennies deter snails and slugs. However, only pennies before 1982 are made of copper; now they are mainly zinc. See our Pest section for good ways to deter differently kinds of worms.

    Since the moth lays the eggs

    Since the moth lays the eggs on the leaves, it makes since to me, that the worms hatch in the leaves, and never have to crawl up the stem, that is in the ground. Thus the penny, whether it has copper in it or not, would be ineffective.

    I don't think that idea will

    I don't think that idea will work. Pennies haven't been made with copper for many years.

    That makes CENTS!

    That makes CENTS!

    Has anyone tried to use

    Has anyone tried to use beneficial nematodes to control tomato hornworms? We had a flea problem in the backyard and were looking for nonchemical flea control when we came across beneficial nematodes. We released three different varieties which will invade and use pests in the soil as hosts, killing them. beneficial nematodes do not harm plants or animals, only soil dwelling pests.

    I used to have hornworms I

    I used to have hornworms
    I used to get hornworms on my tomato plants every year but ten years ago they disappeared, and this year I discovered their demise was caused by Spined Soldier Bugs that live in my garden. The Soldier Bugs look like brown watermelon seeds with a tent-shaped back and sharp points on their shoulders. They pierce other bugs with a sharp beak and suck their juices out, but their favorite food is tomato worms and every plant has one patrolling it.

    This year I put ducks in the

    This year I put ducks in the garden and they patrolled for bugs all season long. I found not a single hornworm on my tomatoes!

    I remember this from my

    I remember this from my childhood and it works. But only if ducks are allowed where you live which unfortunately is not the norm these days.

    I seem to get these SOBs

    I seem to get these SOBs every year. Have done everything from seven to plucking them off. I HAVE discovered that if they have stripped a branch of leaves and you pluck off the worm that the leaves WILL grow back and they CAN produce after that. Now that I know what the Moth that starts this crap looks like I can KILL the MOMS and DADS of these dang things. Side story. I have two container pots of tomates that I have brought in for the season, and I am getting tomatoes from them. Imagine my surprise when I found TWO of these SOBs on my INDOOR TOMATOS! That SAME day I found a HUGE moth in the kitchen, across from where the plants are. We took it outside. If I had known then that THIS was the MOTHER!!! I would have killed it and been done with it. Noooo I let it LIVE! "I'll get you next time you ugly!"

    HA HA HA Diann! Your comment

    HA HA HA Diann! Your comment made me laugh! :] I just looked up their adult form photo so I can kill them BEFORE they destroy my tomatoes!

    Loved reading this. I found

    Loved reading this. I found an UGLY on my tomatoes yesterday and tried to figure out what the heck it was. Thanks to this link, I identified it and am now looking for the MOTHER of this SOB! Mine had eggs attached, which I am assuming are wasp eggs. It is now in a zip lock bag and not long for this world. Perhaps I should let it go because the baby wasp will soon have it to snack on...or I'm assuming so! Thanks for your enlightening comments! Happy Gardening!! Fondly,
    Sonji

    Thanks for the laugh! I just

    Thanks for the laugh! I just came inside to get on the internet to identify this little creature because they have destroyed 4 tomato plants overnight. I squished two that I found but I know there are more out there. I couldn't wait for the white pods to change into a wasp!!! There has to be a solution to this problem. Somebody needs to HELP us out here so we can enjoy our fresh tomatoes.

    so if i understand this

    so if i understand this correctly,if i have found 2 hornworms,chances are i will find many more?? i have never had this problem before in my garden,could they have been in the siol of the plant when i purchased them?

    Hi, Nancy, Thank you for your

    Hi, Nancy,
    Thank you for your interest in The Old Farmer's Almanac.
    To answer your first question, yes, it's certainly possible that you will find more hornworms in your garden. Watch to see if the leaves on your tomatoes "disappear" (get eaten) and for black "droppings" (poop). You might even find that bites have been made in your tomatoes.
    As to whether they came in the soil, we can only offer a maybe. Just because you never had them before doesn't mean you'll never have them. Eggs are deposited on plant leaves and the mature larvae drop off into the soil at maturity. They dig into the soil where they form a pupal cell before attacking the plant.
    Sources suggest that tillage can eliminate as much as 90% of the larvae. So can crop rotation.
    One thing to note: if you see a hornworm with a lot of little "white things" on it that resemble grains of rice, let it live! The white things are parasites that will kill the worm and grow/emerge to become predator wasps.
    I hope this helps!

    I'm a novice gardener with a

    I'm a novice gardener with a few herbs and tomatoes in my front yard.

    I'm surprised to hear about these plants that are supposed to keep the hornworms away. I have a very small garden and it contains one cherry tomato plant, along with two basils and two rosemarys, among others.

    I first noticed that some of my lower and inner leaves were wilting and dying, but I thought it was because I have to rearrange the plant pretty often to support it. It wasn't until today that I saw some stripped branches and huge hornworms. Now that I look at it, it seems like almost all of the inner leaves and up to a third of the outer leaves have egg pouches on them! What can I do? I don't want to kill bees, as they're the ones making my tomatoes possible. Is the pesticide the right choice for me?

    Most of the worms I found were parasitized, but it seems like there are too many for them all to get that.

    Thanks for your help!
    ~CarolAnn

    Hornworms usually start at

    Hornworms usually start at the top of the plant, eating interior leaves. Handpicking is probably best, since you have a small garden. Use gloves to grasp them and drop them into a bucket of soapy water or, if you can stand to, squish them. Gently scrape the eggs off the leaves and destroy them. If you can, it’s good to leave the parasitized hornworms alone so that the braconid wasps can hatch from the eggs; the caterpillars will die at that time. If this doesn’t work, BTK (Bacillus thuringiensis subsp. kurstaki) can be sprayed on smaller caterpillars; it will not affect bees.

    Thank you for the

    Thank you for the info!
    ~CarolAnn

    We had 4 of these worms on

    We had 4 of these worms on our plants this year and I had never seen the wasp eggs on them in the past so I assumed they were their own offspring. They were completely covered with them. If I had known what they were, I wouldn't have thrown them in the firepit. Worked good to kill them! Next time I will just let nature take it's coarse and let the wasps hatch.

    I have been gardening and

    I have been gardening and growing tomatoes for years. This is the first time I have seen one of these owful worms and by the time I found it it had destroyed my tomatoes and eaten nearly all the leaves on two plants. This thing was as big around as my thum and about 4 inches long. I pulled both plants out and tossed the whole thing since I didn't know what it was or if there were others lurking around. I have never ever seen one of these on my plants before. Now I will be buying tomatoes until next summer.

    I have tried every method the

    I have tried every method the reader above have suggested for the last 10 yrs. None of them work except for 7 dust, and pluckin em off and giving them to the chickens. (they appreciate the ugly sobs)

    If soapy water will take care

    If soapy water will take care of the worms when placed in it will it take care of them if I spray soapy water directly to the plant? Thanks

    Yes, but don't overdo it. A

    Yes, but don't overdo it. A few drops in a LOT of water. Specifically: Mix 1 teaspoon of clear liquid dish soap in 1 quart of water to make an insecticidal soap. Spray just when you need it--and spray in early morning or late evening-or it will burn your plants.

    Last year I had eight large

    Last year I had eight large hornworms on two small container tomato plants. This year I am going to try diatomaceous earth. I have read that it destroys the insides of the worms. It has to be dry to be effective, dust it on the plant and soil. It is organic and harmless to pets and humans.

    I prefer Seven and old

    I prefer Seven and old fashioned hand pluckn to remove those sob's. So best of luck in your garden.

    I decided to plant dill

    I decided to plant dill between my tomatoes this year and while the worms are back, they seem to like climbing the dill more and are much easier to spot. I have tried most methods for ridding my garden of them but being diligent and hand picking them works best. Get a good flashlight and go out a few hours after the sun has gone down. Best of luck!

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