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

    Thank you for the info

    I just put a UV blacklight flashlight on my list for purchase. Really appreciate that info. I'm not sure I want to see all the other stuff it can reveal though!

    Also the info about leaving the ones that have the wasp larvae on them is interesting. Did this article really tell us they dont cause any more damage to the plant once they are studded with these little white things?

    I take great pleasure in chopping these things right in half, right on the stem they are on with my Fiskar pruning shears when I find them...like killing an alien life form when their green slime is spilled. I am so mad at them for robbing me of the produce my plants would have provided, I wish I could do worse to them.

    Also, when they are killed and left behind, especially the parts that fall off the plant to the ground (some parts stay clung on and shrivel right there), the rest of nature loves to eat them. I saw little yellow bees just gobbling the carcasses up and of course the ants and all love them.

    Hornworms with Wasp Eggs

    Your assertion is correct: infected hornworms will continue to feed until they are killed by the parasitic wasp larvae. If you want to ensure that there will be no further damage, you can remove the infected hornworm and place it far away from your garden. This way, the caterpillar won’t damage your crops, but the wasps will still be able to emerge and attack more hornworms.

    Below comment

    Worm / Caterpillar on Morning Glory plant and we have several other butterfly plants there but also used to have some tomatoes.

    VERY large green Caterpillar / worm on Morning glory

    Can I leave a picture to know if this is a GIANT Swallow tail OR a Tomato Horn worm

    Green worms on tomatoes

    Are Horn Worms the only GREEN worms to be found on tomatoes. I found 3 smallish green inch worms on my plants this morning, no horns I could see but many holes in leaves and one good size stem almost completely severed in half. Maybe they are baby Horn Worms?

    Green Worms on Tomatoes

    Hi Donna,

    It sounds like you have cabbage loopers on your tomato plants. They eat a variety of different foliage, and are 1 to 1 ½ inches long. Horn Worms are already babies, being the larval stage of the Sphinx Moth. Horn Worms are about 3 inches long. We hope this helps!

    Green Worms Imbedded In The Fruit Itself

    What remedy do you suggest for those smaller green worms found imbedded in the tomato fruit itself? Finding limp, mushy green tomatoes with worms busily devouring the fruit though no sightings on the limbs or leaves. Oddly, it's random-- surrounding tomatoes seem both uninhabited and healthy. So far, no sightings of the larger horn worm.

    Tomato Fruitworms

    The pest you’re describing sounds like the tomato fruitworm, which is known to bore into tomatoes and cause them to rot. Once they get inside the tomato, there’s not much you can do, so stop them beforehand by routinely checking for eggs on leaves and spraying with a natural insecticide, like Bt (Bacillus thuringiensis).

    Hornworm

    I just found the big est green horn worm or should I say the biggest Catapillar I've ever seen in my life

    Horn worms

    Very jnformative, thank you.

    hornworms on my collards and kale

    I've had whole collard plants eaten and kale that was chewed this year and could not find anything eating them, just some black "poop balls" left behind. Today I notice a tomato plant completely bare of its leaves and found this huge hornworm covered in the wasp larvae. My question is, Is it safe to eat greens that have been chewed by these creatures?

    safe greens

    The Editors's picture

    It should be OK; we haven’t heard about any cautions regarding hornworms affecting edibility of crops in that respect. After harvesting, cut out any damaged areas and throw out any rotten leaves. Then wash the greens thoroughly just before eating, using cool running tap water. You can blot the leaves dry with a paper towel or use a salad spinner. Be sure that your hands and any utensils/tools and food preparation surfaces are clean. (It is recommended that hands are washed for at least 20 seconds with soap and warm water before handling food.)

    worms on tomato plant

    i have what i thought was the cabbagelooper doing damage to my plants but now i'm not so sure. i've been collecting the cocoons at various stages and have come across many that look like a worm encasing hundreds of eggs. could this be a way of reproduction for them that i'm unaware of?
    please advise

    eggs

    The Editors's picture

    Are these cocoons on a caterpillar? See the photo of the tomato hornworm with the braconid wasp cocoons above - these are one insect per cocoon. Braconid wasps are parasites of the hornworm. If you see these on a worm, leave them be. The hatching wasp larvae will take care of the hornworm pest.

    The eggs of a cabbage looper are laid with no protective covering on leaves, singly or in small clusters, and are whitish yellow to green. Each pupa is encased in a thin white cocoon under foliage; the pupa itself is green, then turns brown to black, before transforming to a moth. A few insects make egg cases, such as praying mantids and spiders (egg sacs), which contain many eggs. A common tomato pest that might do this, though, does not come to mind at the moment.

    Fruit Trees - plums ,Figs , Tangerines , n more

    Don't like worms to see in my garden . Thanks for all the Infos.

    Hornworms

    I have this worm eating my tomato plants,but it is black with gold v-stripes. What should I do with it

    tomato plant pests

    The Editors's picture

    This sounds more like an armyworm. Besides handpicking, you could try applying the natural bacterium Bacillus thuringiensis (Bt) for control. Talk to your local garden store.

    Tomato Hornworms

    We're under attack!!! Never one to be afraid or grossed out by bugs, but these are no bugs! They're creatures! We never had them before & planted our tomatos & peppers in containers with new soil. We're checking daily & removing them regularly. Also spraying with soapy water. Lots of great info on your site & now that we know about the wasp eggs & the villain moth, we'll be on the hunt. Thanks!

    Saw one hornworm

    I found and removed one large hornworm from my tomato plants today. This is the first time I have ever seen one. Can they be found in isolation, or do I probably have more?

    Tomato Hornworms

    The Editors's picture

    If you find one tomato hornworm, look for others.  Their mothers deposited a bunch of eggs from which they hatch. Plants should be examined at least twice per week during the summer to check for tomato hornworms. They’re easy to find because they’re big!

    hornworm

    While pulling outthe last of the tomato plants I found 2 hornworms, one about and inch long and the other about two inches long. The smaller was covered with the wasp eggs but the larger was not. I have a 5 year old nephew, I gave him the worms and he put them in the little screen cage that he has. The next morning the larger worm also has these eggs. Does this mean that the worm was 'attacked' by the wasp at an earlier time. how is this process done, does the wasp 'bite' once or does one 'bite' produce all of these eggs?

    hornworms as pets

    The Editors's picture

    Hi, Mary Anne, Yes, it is possible that the worm was attacked by the tiny wasps before it went into the cage. The “eggs” are actually cocoons; the eggs were laid under the “skin” of the hornworm and these are the result. As for how it’s done…a special type of braconid wasp inserts its eggs into the caterpillar (hornworm). The eggs hatch into wasp larvae that feed on tissue in the caterpillar. This eventually changes the color of the hornworm but—fear not—it is still alive. The wasp larvae eventually chew through the hornworm’s skin to pupate…and each white “egg” attached to the caterpillar/hornworm is the cocoon of another special braconid wasp. Before long, the new wasps will break free and be ready to mate and attack next year’s hornworms.

    There is a lesson—or one heck of a bedtime story—here for you and your nephew. Good for you for going after the detail! And thanks for asking us. (We learned something too.)

    Tomat worms

    I found 4worms destroyed them. About thirty minutes later found another. Today I have checked my plants 4 times and just found one that was not there earlier. I have marigolds close to them. Never had this many worms on my plants before. Does the marigolds draw them?

    Hornworm

    You need to add jalapeño to the food list

    Tomato hornworms

    I only planted two tomato bushes and two green pepper bushes this year. This morning I came across these buggers. I thought my bushes were looking a little wilted after I picked a big bowl of tomatoes last week. I picked off 7 and am so creeped out about these bugs that I may just cut down the bushes!! I have never had these bugs in the 25 years I have been planting. They are not on my green peppers but there is a lot of dropping on the leaves so may pull them out too!

    Tobacco Horned Worm

    This was a great article. :) You do need one correction though. You say these worms do no sting. You have never got tapped with that horn on the back then. lol They do sting and it feels like fire when you get hit. Adults need to be very aware when removing them not to get stung and children do not need to handle them because they can get hurt.

    ... it does not have the capability to sting or pierce the skin

    If you have ever suspected that you have been bitten by a tomato or tobacco hornworm, chances are it wasn’t a hornworm that bit you. A tomato or tobacco hornworm (or any hornworm or insect for that matter) will do whatever it can to protect itself, especially if you handle it for too long. However, it doesn’t defend itself by biting. A hornworm will spit out the contents of its stomach, it will wiggle and thrash about, and it may even wrap itself around your finger, but it does not have the capability to sting or pierce the skin.

    (Ref: www. allaboutworms. com/tomato-and-tobacco-hornworms)

    Thank you

    Thank you

    Hornworm tragedy

    I agree with the one comment as to “Feels like fire” , in reference to being stung/bitten by these things. Anyone that has felt the sting/bite from one of these things will never pick one up with their bare hands again. The first time I had this happen I thought possibly it was me or a wasp encounter etc.

    The second time my father-n-law tried to warn me to look for them before picking the tomatoes. Too late as one was under a leaf above the tomato and it pierced the back of my hand. Felt like fire and a stabbing pain all in one. I do not claim to understand whether a bite or sting, but. I now look before I pick tomatoes and I use pliers to remove these things. As they may have gotten me twice, but never a third time if I can help it.

    wasp larva

    So the white grains on the back are wasp eggs. How do you insure they multiply?

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