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.

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    Reader Comments

    Leave a Comment

    Hornworm

    I find taking some small snippers outside with me when I check my tomato plants is my best option. Upon locating a caterpillar, I just snip it in half instead of grabbing it off the stem and placing it on a hard surface to squash. It’s also much faster. I then see wasps coming to feast on what’s left of the caterpillars.

    UV Light

    I've been checking the plants every couple of nights with the UV light ever since I put them in the ground. They glow nice and bright. I've gotten at least 5 of them while small and plants are doing great!

    Tomato hornworms

    Noticed several of our tomato plants' leaves "crinkling up" ... examined our 14 tomato plants closely, discovered 7 tomato hornworms - had never seen these little green buggers before. If we had chickens, we'd feed them the hornworms, but we don't, so the immediate remedy was/is to pluck them off the plant they are on and squish them, straight away.

    Horn Worms “black light”

    Use a black light at night. You will see every single one in your garden. Repeat for a few days until you see no more. Hit them quick. They will destroy your garden quickly.

    Tomatoe horn worms

    You can find them at night with a black light. They stand out like a flag.

    Tomato hornworms

    I only have one cherry tomato plant by the house and I planted basil around it. Basil is doing great but I picked 5 hornworms off of my tomato plant last night. So much for the basil plant idea. But my chickens did like the snack

    Hornworms = Perch Bait

    Our perch in the pond enjoy tomato hornworms for a snack. Grub worms are also a great bait!

    TOMATO HORNWORMS

    A Master Nursery in Lakewood CA suggested planting a Borage Plant nearby. Apparently it confuses the moth as to where to lay the eggs. in the last 3 yrs, I have not had a hornworm since I have planted Borage nearby.

    Is it fate or by chance?

    This morning I checked my tomatoes, about 60 Roma plants, and found about 15 nice sized hornworms. Put them in a cup, walked to neighbor's house, fed their chickens and I think the chickens were smiling. Came home and this article was in my email.

    Hornworms

    I usually find them on my moon plants (moon flowers) late in the summer. They destroy the leaves & can eat into the buds before they bloom in no time.

    Hornworms

    It is a fallacy to say hornworms stay with certain plants. Yes, they like tomatoes and plants in that family...but I have found them on lavender, surprise lily leaves, asparagus fronds, one got lost on the potted dahlia but didn't seem to like it much. I have everything in pots this year and the birds are flocking, but they are not getting them all. I use Bt npic.orst.edu/factsheets/btgen-html and it works, but this year the rain has hit more often than the sun so it is all soggy and the little buggers are everywhere.

    Hornworms

    First time I saw one of these it scared the living bejeebers out of me - I swear it turned its 3 inch long body towards me and hissed.

    Tomato hornworm/ tobacco hornworn

    These pests can also feed on other pepper plants. They can destroy a plant in less than a week once they have reached a good size.

    Don’t kill! These guys turn into very beneficial moths!

    As mentioned, hornworms turn into hummerbird moths which are very beneficial pollinators for gardens and the overall ecosystem. Instead of killing the hornworm how about planting a row of plants that they enjoy and that you are willing to sacrifice to them. This way you can move the worm over to those plants to eat instead, and your garden will get to benefit from the pollinating moths after the worms transform. Before jumping to conclusions about a so called “pest”, take time to consider it’s place and reason so that we can support the ecosystems that have evolved over thousands of years.

    Hornworms

    I examine my six tomato plants and red bell pepper plant daily. In the past two weeks, my husband has pulled off at least nine of these little monsters. It amazes me how quickly a hornworm just "appears". Does anybody have an evolution on how this little sucker grows? I swear I do look at the tomato plants very closely and see nothing, then I look again and a worm appears. We pull off three this morning and put them in a cup. I watched two ofthem latch their little caterpillar legs together while the third pushed them under as it tried to selfishly save itself.

    Found our 1st two

    We had been wondering if we would get these in our little raised garden bed, and just found two (the first one with a shriek). I didn't know drowning was a way to deal with them, but I dropped them into the planter platter we used for a bird bath and that definitely did them in. And some happy birds apparently snagged them before I made it back to my window five minutes later. Circle of life. I've noticed sparrow flusters (clusters of flutterbombs) paying a lot of attention to my tomato plants lately (the past week). I'm wondering now if they have been feasting on eggs and fresh hatchlings...

    Thanks to krp for the tip on biting. And thanks to Mr. Smesler for the tip on blacklights. I'll be trying that this evening!

    Biting

    You're a liar if you say they can't bite.

    Whenever I get pick one off, it tries to bend up and bite me. I once got a bigger one that actually drew blood!!!!

    If you want to say that they can't bite, I can assure you that they can AND WILL!!

    I don't care what your entomology textbook may have told you. I know from experience for a fact that they DO bite.

    My preferred method of dealing with them is to either take a long-nosed lighter and set their horned tail on fire, or strip off the leaf they are on and drop the whole thing in a bucket of water. Doesn't have to be soapy water, they will still drown

    Seen these little beasts in my herbs and celery.

    I can attest that I've seen these little beasts twice so far. I live in Colorado and we recently were hit by a huge swarm of moths which have thankfully died down now. I caught the first one eating my sage and basil, which I quickly removed and put it outside to eat some more wanted-to-remove plants. The second one came just today where I caught it in one of my pots with a celery stalk missing most of its leaves. It was also removed and humanely released into the weeds. Hopefully the rest if my plants, including my tomatoes, will be spared from this creature's attacks.

    Hornworm

    Can a tomato plant survive a hornworm attack? Mine were left with only a few leaves overnight, can they be saved?

    Survive Hornworms

    The Editors's picture

    Hi Lisa,
    With only a few leaves left, chances are the plant cannot be saved. You could try leaving it and see if it starts to grow again, but the loss of leaves will most likely stunt the overall growth of the plant. Another option is to purchase a new transplant from a local nursery, as it’s not too late to try replanting. We hope this helps!

    Tomato Hornworms HUGE!

    Today we found these little devils eating the plants. At least 6 on one small plant. I planted seeds that had already sprouted inside the tomato - as an experiment. Could the larve have been inside the tomato?

    Lost (and found) tomato hornworm

    I've been gardening since the 1970's.

    This year I had a problem with my rhubarb being eaten. It was a mystery and stunting the plant. Yesterday after finishing weeding I found a rather large tomato hornworm eating it. I had no idea that they ate rhubarb. I viciously killed the beastie. I felt better. I hope the rhubarb will start putting out taller stems.

    The only reason I can come up with for this behavior is I didn't put out my tomatoes, peppers and eggplants until late and in beds far from the one I had last year. It was about 5' from where the tomatoes were last year. This years plants are in the opposite direction and at least 8' away.

    Tomato Hornworms

    I used to have problems with these pests until I planted Borage next to my tomatoes. The Borage plants have a prickly underside on their leaves and the Hornworms don’t like it. I haven’t had problems since. Make sure to start your Borage seeds as early in the spring as possible so they’re ready to plant with the tomatoes.

    Tomato worms

    This is my 1st year with a raised vegetable garden. I have tomatos and eggplant. I have notice a few holes in my tomatos. I decided to spray my whole garden with Dawn dish soap and water in a small spray bottle. So far so good. No worms, no more holes in my tomatos. It has been raining for the last 4 days. I will check them again and spray if necessary. I really did not want to use pesticides. When I turn the garden this winter I may add something to the soil at that time. Hoping this simple trick works.

    Finding Hornworms

    The tip I read about using a handheld UV light to finding hornworms on my tomato plants proved to be correct. They almost glow against the black color of the the leaves. Good stuff.
    These weren't the big muthas but the juveniles, inch or two mostly. The black light works and makes it so much easier. I won a battle.

    They love my jalapenos as much as I do!

    I started a container garden this year with red and purple bell peppers, jalapenos in a separate container and a sweet meyer lemon tree in another container. I first came across these nasty guys with the bell pepper plants a few months ago. I thought I had it taken care of with neem oil but yesterday had to throw away all 6 bell pepper plants. Although I inspect my plants every day, today I will be throwing away my jalapeno plant due to the magical overnight appearance of the hornworms feasting on the jalapenos (and I just picked about 15 jalapenos this weekend to freeze, did not notice a thing). Please help me save the Sweet Meyer Lemon tree with any suggestions!!!

    Hornworms

    Do tomato or potato hornworms attack rhubarb plants ?

    Hornworms and Rhubarb

    The Editors's picture

    No, tomato hornworms feed primarily on plants in the Solanaceae (nightshade) family, which includes potatoes, eggplant, tomatoes, peppers, and others. Rhubarb is not in this family, so it is not in danger of being devoured by hornworms!

    Hummingbird Moths

    I’m concerned about our pollinators- the Hummingbird Moth. Any suggestions for where to PUT the tomato worms INSTEAD of killing them?

    Where to Put Hornworms

    The Editors's picture

    Hornworms feed on plants in the Solanaceae family (commonly known as “nightshades”), so they’ll need to be placed on another plant that’s in this family in order to be able to develop into moths. Tomatoes are a nightshade, as are potatoes, eggplants, peppers, and tobacco—but these are all plants that you normally wouldn’t want them to eat! There may be wild Solanaceae in your area, such as jimsonweed, horsenettle, or nightshade itself, where you could move the caterpillars to. However, these plants are poisonous, and thus hard to find. 

    Hornworms may feed on petunias as well. If you can’t find any wild nightshades, perhaps you could set up a couple petunia plants for the hornworms. Or, in future seasons, plant more tomatoes than you need, designating some as “caterpillar-friendly!”

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