Tomato Hornworms

How to Identify and Get Rid of Tomato Hornworms

Tomato Hornworm
Amanda Hill

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.

    2022_gardening_calendar_spring_ad.png

    Reader Comments

    Leave a Comment

    Dawn &Water Solution

    I did the same with similar result. Lost several tomato, jalapeno, and Italian pepper plants to the soap mix while trying to combat the worms. I was told later to only use a very small ratio of soap to water. This is my first year gardening so I expected a learning curve. Next time I try this I will do a small test area on a single plant.

    Hornworms

    I go out after dark with a flashlight and a pair of scissors. I just cut them in half and let the good bugs have dinner on me.
    Just one thing if you see a similar looking worm on your dill please don't kill it because it's swallowtail butterfly. I plant dill in various areas of my yard just for them.

    Natural prevention

    First year growing in containers and hope for a better yield. Last year due to excessive rain when growing in back yard I experienced cracked and bottom rot fruit so I went to containers to allow moving plants to control moisture. For insect repellent I read to mix in a cup of hot water a tablespoon of Baking Soda, oil I used olive oil though something called fern oil is directed and only a drop of dawn dish soap only to emulsify oil into solution for spraying. Once the cup is mixed pour into sprayer with water. Shake well and I always try to use water that has sat dormant for a day or two so any chlorine residuals are dissipated. I love and been growing home grown tomatoes for years and must enjoy the challenge and learning more about gardening because for the time and effort spent over the years it would be cheaper buying them from the local farmers market. Do to the deer, rabbits, raccoons, and birds I now have a potable fencing system.

    Blossom-end rot

    Blossom-end rot - rot on the bottom of the tomato - could be a result of insufficient calcium in the soil. Crushed eggshells break down and replenish the calcium in the soil.

    Calcium

    Tried this on my squash this year and very pleased. Crush tums (2 per gallon) and add to a gallon of water...works great to add calcium with very little cost.

    Horned worms

    These pests devoured my trumpet plant! I picked off at least 15 of them, thinking at first it was deer that devoured my plant. Upon looking further it was these same worms that affect tomato plants! We drowned them then fed them to the wild turkeys. Totally taken aback that they ate my plant! I hate them!

    Hornworm eggs

    I had those nasty creatures & ended up pulling off what tomatoes I could that were still geeen & hope they ripen in the house or the windowsill. Those nasty eggs(larvae) left my nice new deck with green spots! How do I get rid of the stain without harming my deck? It hasn't been stained yet. Those creatures are gross!

    Tobacco vs. Tomato

    The pictured worms are actually Tobacco Hornworms. The tobacco hornworm caterpillar has black margins on its white stripes and it has a red horn, the tomato hornworm has green margins on its white stripes and the horn is blue. Just as hungry though!

    Hornworms

    Is it okay to spray a dawn and water solution then spri lie with cayenne powder on purple Cherokee tomato plants to treat for hornworms?

    Dawn & water solution.

    I started having a problem with green tomatoe worms so i used a solution of dawn & water to spray the plants. I think it is killing the plants as the leaves are turning brown & the blooms are falling off. They are not looking good. I wouldn't use it.

    hornworm

    I noticed my tomato plant leaves curling, a week or so ago and attributed it to the Texas heat. It had been many years since I'd had a tomato garden, so I had forgotten all about that 'sign'. I'm hoping the pesky worms have all been located. My question is, will the leaves of my plants uncurl and look full and lush again?

    Hornworm Damage

    The Editors's picture

    Leaves that have been directly chewed or affected won’t recover, but any new growth should be fine as long as the insects didn’t infect that plant with a disease. Keep an eye on the plant to see how it develops.

    You have to rinse it off.

    I use dawn (actually the store brand version of it) on my plants all the time to get rid of soft-bodied bugs. It works great. HOWEVER, you have to rinse it off. Spray the plant then wait about 5-15 minutes then use a hose to rinse the soapy water off thoroughly. It doesn't take long to kill soft-bodied insects with soapy water. Most die instantly. Some people say using soapy water sprays with dawn or other soaps with degreasers damages your plants as it kills the good bacteria on the leaves. But my plants always look and grow healthy as long as I rinse the soapy water off. You have to understand that most gardening information, whether on blogs, videos, books, etc, is purely anecdotal. For me, I use what works so I can have a bountiful harvest. I grow organically - the only exception is my use of soapy water sprays. I have to keep the bugs at bay or else I might as well stop gardening altogether.

    Horn tomato worms

    They are not just tomato eaters. I just found 3 large juicy ones on my small petunia like plants. WOW, didn't expect that. I pulled the plant out since it was just a twig now and placed the plant with worms attached in a plastic ziplock Baggie. Off to the dump they go!

    My method for diposal

    Since I use no chemicals in my garden and hand pick off all pests found I feed them to wild birds. I have a platform made from scrap wood in the middle of my garden space where I toss the pests. This, in turn, attracts more insect-eating birds to the garden I have seen them scratching and feeding on something just below the surface of soil on several occasions. If have chickens or ducks just add pests to their feed. When I had chickens I would let them into garden in spring before planting and in fall after crops pulled and let them feast.

    Tomato Hornworms

    My grandmother used to go out in the evenings or early mornings with a pair of scissors and just snip in half every hornworm she found - never had to touch them.

    1st time I've seen these

    I noticed a lot of black dropping on the ground around my cherry tomato plants about 1 month ago they looked like coffee grounds because we had some gusty winds the night before I thought that they had blown off the roof and as I was sweeping them away I notice a large green caterpillar I googled it and discovered it was a tobacco hornworm so I went over all my plants and removed over 20 all varies sizes then I got my husband to check over them behind me and discovered a few more that I missed. The next morning there were more droppings and I removed another 10 and for the next 3 mornings after more droppings but only 3 this time then 1. Then nothing I thought I was in the clear then just last week I found a huge amount of dropping around by Better boys and discovered the biggest fattest hornworm yet. This is the 1st year I've seen them do you think I will get them every year now? I forgot to mention that all my Tomatoes are in containers on my deck with fresh soil every year.

    Tomato Hornworm

    The Editors's picture

    Hi Lesley,

    The tomato hornworm pupates into a sphinx moth, also known as a hawk moth. They lay eggs on tomato plants that will turn into the hornworms. Since you change your soil every year, it is unlikely that they will be a consistent problem year to year: No pupas will overwinter in your soil. The moths are just finding your plants. Keep in mind, right now is prime moth season. As summer moves on into August, you will see less sign of caterpillars and moths.

    Cutworms or hornworms on tomato plants

    Years ago, cutworms would devour my tomato plants just before I could harvest tomatoes until my mother-in-law passed along some tried and true Wisdom to me. When you plant your tomato plants take a "WHITE" Styrofoam cup size Large, cut the bottom out of it, place it in the hole and put your tomato sprout in it, be sure to leave the cup up out of the ground most of the way (use just enough dirt to hold it around the plant). As your tomato plant grows make sure that you prune any stems that can touch the soil which are usually the first stems so the worms cannot crawl up the stems that they can reach from the ground outside the cup. The white cup acts like a barrier to keep the cutworms off the plant, this is the same reason that crickets are kept in white Styrofoam bait boxes, cutworms & hornworms like crickets will not pass over WHITE - True story, I never have had a problem since nor has anyone I have shared this knowledge with - Blessings from Mary Joe Green Taylor !

    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

    The Editors's picture

    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

    The Editors's picture

    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 Editors's picture

    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?

    Pages

    FREE BEGINNER'S GARDEN GUIDE!

    Sign up for our email newsletter by entering your email address.

    BONUS: You’ll also receive our Almanac Companion newsletter!

    The Almanac Webcam

    Chosen for You from The Old Farmer's Store