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

    Leave a Comment

    Hi, Donna, It sounds like the

    The Editors's picture

    Hi, Donna,
    It sounds like the tomato pinworm. These overwinter in soil, especially that of greenhouses. The first recommendation is "clean soil." (Don't we all think we've got clean soil?) Essentially, if you buy transplants, get your tomatoes from a trusted source. Keep your garden clean last season's plant refuse. Rotate your crops.
    If you see evidence again (small holes in the leaves, for example), remove the leaves from the plant. If you see holes in the tomatoes in season, use any that are edible and dispose of the remainder.
    We hope this helps.

    I'm in the Boulder, CO area

    I'm in the Boulder, CO area and I've never seen hornworms as big as here! Moved here from Illinois last year and had them there, too. I have Marigolds all over the place right next to the tomatoes and basil less than a foot away - tons of it. Nothing helps except picking them off although I haven't tried the Bt stuff - afraid to!

    Last year when I noticed that

    Last year when I noticed that I had tomato hornworms feasting on my tomatoes, I picked and destroyed what I could find. Later, after dark, I went out in the garden armed with a blacklight on an extension cord, and lo and behold those that I missed lit up like neon lights among the leaves! Easiest way I know to get rid of the little beasts!

    Just had to share: My

    The Editors's picture

    Just had to share: My community garden has been plagued with hornworms for years. This year not so: I saw only two on my plants, and each was covered (and so destroyed) by tiny white wasp cocoons.
    To attract parasitoid wasps, provide beneficial plants nearby, such as those in the carrot or cabbage families. Specifically you could include sunflowers, coriander, cornflowers, sweet alyssum, and asters.
     

    I just seen one for the first

    I just seen one for the first time today and was bigger then a bic lighter and long ..

    I also just saw my first one

    I also just saw my first one ever!! Thought it was some kinda mutant caterpillar lol

    bT is safe and it works. One

    bT is safe and it works. One bite and they stop feeding. It works on all kinds of caterpillars, not just hornworms. Spray seems to not be the problem since you can wash it off,and it is in the soil naturally in small amounts, but when it is used in corn or other seeds as a GMO not so sure that it is safe.

    You wrote earlier by saying:

    You wrote earlier by saying: "don't crush them", why not? When I found one on one of my tomato plant, I sniped him in two. Is there a consequence?

    I'm curious about this as

    I'm curious about this as well. Why not crush them? Prior to reading this, I found one and I did crush it - will it attract others or something?

    Other than it being a icky

    Other than it being a icky job that could leave a stain, it is OK to crush them; it is a popular control method. For those who are squeamish about crushing so large an insect, though, dropping them into soapy water is less gooey. We'll revise the article so that it is clearer. Thank you!

    Today I found several leaves

    Today I found several leaves of my potted tomato plant eaten...there were several "horn worms" attached to the branches, so with a long handled pair of plyers I pulled them off and dropped them in a bucket...I then sprayed the plant with liquid "Sevin"...about an hour later I found several large and small worms laying on top of the soil in the pot...by the way I also sprayed the ones in the bucket and they were dead...

    Ridding cut worms from tomatoes

    Pest verses Plant
    I've been told by an agronomist that using "Sevin" on tomato plants for Hornworms will also eliminate the beneficial insects such as the pollinating bees and without bees we have no garden yield.
    Has anyone tried spraying plant with soap and water mixture?

    I found Hornworms on all my

    I found Hornworms on all my pepper plants, I am sure they have been munching on my strawberries as well. They are really harming my garden! Is there a way thatI can get rid of them through a "biological cycle" so to speak? Can I purchase these wasps as opposed to attempting to attract them? Or is picking/killing them and using BT the best option? Does Neem oil work? Is there a use for these worms? I would rather not mass murder creatures who are just trying to survive. (I know it sounds new-agey, but I would rather avoid that. Thank you!!!

    To clarify my earlier post I

    To clarify my earlier post I had a huge infestation of hornworms the first year. I did a lot of research on organic gardening during the off season. Borage is an herb and when planted in a cross section between the tomato plants it gives off a scent that Hornworns hate and will not go near. Ever since i started using this method I havent seen another worm on my plants. Hopefully it works for everyone else as well.

    I watched a red wasp hover

    I watched a red wasp hover in, bite a hornworm, about 3 inch long, fall about 3 leaves down and then eat the entire hornworm. The hornworm kinda melted into the wasp jaws.

    Since then I have left the two wasp nests alone out near the garden.

    I haven't really had much of a problem but those worms can really do damage in a short time. I am trying container potatoes this year, and 1 hornworm decimated one plant and half another before I found him. I find the droppings the dead give away. Sort of look like green mini croquet balls. Anyway after seeing these I started looking harder and sure enough a huge hornworm chowing down hiding in plain site. Similar to how the article describes finding one as shocking. Anyway killed it and placed it on the bird offering alter so he should be gone by this evening.

    Tomatoes are a total disappointment this year anyway so no big deal. Next year only heat loving varieties.

    Really appreciate your most

    Really appreciate your most informative article/response.. Just found my FIRST hornworm today, bagged him up and threw in in outside trash bin(and, YES, Very cold-hearted since I have a difficult time killing insects, rather go out of my way to spare and relocate them OUTSIDE!!! At any rate, 1/3 of my tomato plant was eaten..and Not by deer(due to tall fencing!!) LOVE the idea of offering the "Little Devils" to the birds though..LOL!!:):)

    When I found my first

    When I found my first hornworm, and double-checked it's identity using google images, I was intrigued by a photo of one being held in the mouth of a cardinal.
    So I put this 4" long caterpillar on the pavement near my bird feeder (so it would be easily seen). Sure enough, within about 10 minutes, a female cardinal took it. She dropped it twice, but she was determined. I don't like squishing, but I am happy to provide the cardinals with food.

    Be Careful With Neem Oil I

    Be Careful With Neem Oil
    I also read that neem oil work's well at getting rid of garden pest, but before you spray check the label, it will definitely kill your plants if used in area's where the weather is Hot. I have also tried hot sauce, garlic, dish soap with water and needless to say it was not effective in the least.
    I inspect my plants daily, and pick off the nasty hornworms by hand. It is the only thing that I have found that works the best so far.
    Happy Gardening to All of you.

    No, these are not the worms

    No, these are not the worms I'm talking about. I have never seen these before. I know what the hornworm looks like. These are BLACK WITH YELLOW STRIPES DOWN EACH SIDE.

    Just look up tomato hornworm

    Just look up tomato hornworm on Google and there are lots of pictures. I saw a worm just as you described

    It is a catawba worm.

    It is a catawba worm.

    I think the catapillar you

    I think the catapillar you may be describing is a milk weed catapillar..which will turn into a monarch butterfly...

    Last year was my first year

    Last year was my first year dealing with hornworms. I take pride in my tomatoes. From seed to harvest i trend my pants. It was a surprise that these large lazy worms were treating my hard work like a buffet. We also have chickens so we let them loose in the gardens. Chickens are a great way to help control the pests and the chickens really seem to like the hornworms. However there is still a need to check my gardens everyday to make sure there are no pests. But i don't mind. Looking forward too another great gardening season.

    dishwashing liquid IS A

    dishwashing liquid IS A chemical...hello....

    Everything is a chemical or

    Everything is a chemical or chemical mixture...HELLO

    Thanks for your comment. So

    Thanks for your comment. So true.

    The cocoons were stuck tight,

    The cocoons were stuck tight, and the worm kept flailing sbout, so we quit. It the escaped, time to find a new one!

    Connor, Thanks for sharing.

    The Editors's picture

    Connor, Thanks for sharing. That worm is what they call the "walking dead" due to those cocoons.

    My kids also want it as a

    My kids also want it as a 'pet', so is there a way to take the eggs off? Thanks!

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