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.

    Reader Comments

    Leave a Comment

    This is a first! Once the

    The Editors's picture

    This is a first! Once the wasp eggs hatch, the hornworm will be eaten. It is the cycle of life. We have never removed the cocoons and probably would not, but let us know what happens!

    We found a hornworm with 5

    We found a hornworm with 5 white, bumpy specks on it. Are those eggs from a wasp?
    We're guessing they are.

    Those are the white cocoons

    The Editors's picture

    Those are the white cocoons of the wasp.

    We live in southern Arizona;

    We live in southern Arizona; our backyard consists of grass, 4 trees (orange, desert willow, mesquite), and a large variety of roses, lantana, and vines. We have found tomato hornworms wandering in our yard approximately every 6-8 weeks for the last few years. However, for the last couple months we have been finding them dead all over the yard. There have not been any signs of involvement by wasps that we can tell. Their coloring is no longer bright but instead is kind of brown, and they are kind of soft and mushy (it is evident when I pick them up with a pooper scooper--the one I picked up this morning actually tore into two pieces). Does anyone have any idea of what kills tomato hornworms other than wasps? The only thing I can think of that has been unusual around here is a phenomenal weather situation July 15 (2013) when our neighborhood was hit, ripping 2-story high, decades old trees out of the ground, root and all, throwing them into homes, ours included, so I have wondered about the possibility of some soil disturbance or something, I don't know. Help! Thank you kindly.

    We're stumped. We can only

    The Editors's picture

    We're stumped. We can only imagine wasp predation.

    I too live in Arizona. I hear

    I too live in Arizona. I hear from a lot of people that soap and water and then just spray your plants repels the pests away and is safe for the plants. I have yet to try it but after finding 3 of those hornworms today on my tomato plants it will be tried effective immediately. also with some netting/shade screening as well.

    I planted about 6 or 7 plants

    I planted about 6 or 7 plants this yr . We had a ton of tomatoes , some plants were 3 to 4 feet wide, alas I too believe I have these ugly worms. I have found holes right through the tomatoes at times. I have a question , is it safe to cut up the tomatoe and eat what the worm has not eaten ? Are there effective moth traps out there ? I have read about the sticky traps for indoor cereal moths .
    Should my ground be rotatiled in the late fall to get rid of any edges , or worms? Next yr I will start going out to examine the plants in evening I guess , if they make good fish bait , worms beware!!

    I don't know, maybe they are

    I don't know, maybe they are fruit worms , I guess I will have to find one to identify it. Does newspaper work with deterring fruit worms?

    If your pests are tomato

    The Editors's picture

    If your pests are tomato fruitworms, you can control them by picking off any leaves that have tiny white or creamy eggs on them (check both sides of the leaves). Introduce beneficial insects, such as Trichogramma wasps or lacewings. Place row covers over the plants, at least until the plants flower, to prevent adult moths from laying eggs on the plants. Spray Bacillus thuringiensis (BT). Till the soil before and after the growing season. Plant tomatoes away from corn, which is a major host for these pests (in which case, it is called a corn earworm).

    As for whether to cut out the bad part of the tomato and use the rest, we wouldn't recommend it with fruitworms. Because these larvae live inside the fruit, they eat, tunnel, and leave waste inside.

    Hornworms, however, mainly attack the foliage but may also take bites out of the fruit. They do not live inside the fruit throughout their larval stage, however. If your pest is a hornworm, it might be possible to cut out the bitten area of the tomato fruit and use the rest (after a thorough washing); be sure to inspect the fruit thoroughly first, to see how far it has been eaten, and whether the insect has left frass (waste) as well--in which case, we'd suggest not using the fruit.

    I am a preschool teacher.

    I am a preschool teacher. Yesterday, my kids and I found a big fat beautiful Horned Tomato Worm on our tomato plants in our outdoor classroom. He is now living happily in our classroom munching on an endless supply of tomato leaves with 12 very excited and eager kids watching him. We have added tall sticks for him to climb and lots of leaves in hopes that he will build a cocoon and hatch into a moth. They have found books about caterpillars, looked at pictures on the internet, and even collected leaves to feed him. They are so excited to show him to everyone willing to look.

    Yes, I know these worms are pests for most of you, but for this class, this worm is a wonderful opportunity for the kids to experience the bear witness to the magnificent and wondrous cycle of life while fostering language, science, math (rulers to measure him and counting days if he forms a cocoon), cooperative learning, ownership /responsibility, peer interactions, and so much more. For me, finding this garden pest was just an excuse to turn a little pest into a teachable experience.

    Thanks for sharing,Denisestl.

    The Editors's picture

    Thanks for sharing,Denisestl. We can imagine that hornworm munching away as hornworms do. What a great purpose for these otherwise "cute" green caterpillars.

    My big geraniums were striped

    My big geraniums were striped in just a few days. I didn't think geraniums had many enemies but when I looked closer they are covered with baby horn worms. I want to just cut them way back to try and control the infestation.

    I, too, am a fan of

    I, too, am a fan of hornworms. They have been on my tomato plants and seem to only prune the tops. Almost always, they get the cocoons on them, meaning they are dying. I don't like the idea of something being eaten from the inside out. I just found one on a flower and it has eaten the top out, but I don't care as I get the opportunity to study him up close. Tonight I am observing him trying to find something to eat as there are no tomato plants where he is, and he is trying to eat, I believe, my small yaupon shrub. I don't how he can eat these tougher leaves. I did notice that his mouth is protruding when looking for food. I have never noticed this because I have never seen one at night. Very interesting.....He does not have the parasite cocoons on his back. Hopefully, he doesn't get them. He is pretty large. (I am a former teacher, retired) and a lover of science.

    What a wonderful teacher you

    What a wonderful teacher you are!!

    Good job! Your kids are so

    Good job! Your kids are so lucky to have you as a teacher. The worms may be Pests perhaps, but just the sort of thing to fire a child's imagination and, who knows? May start someone on the road to being a scientist ... Or better yet, an inspiring teacher!

    The first tomato horn worm my

    The first tomato horn worm my dad found in the garden became my pet at the age of 4. They are beautiful, soft and easy to care for. The cocoon and transformation was so fun as a kid, and they are so unusual, I couldnt wait to find a new one the next season. I spent hours patiently tracking their munching and pooping so I could bring it into my kindergarten class to share. We ended up keeping it as the class pet, and watched the transformation throughout the fall. Every year, my old kindergarden teacher would call me out of class to ask if I could find her another worm for her current kids. I brought her a worm each year until high school. I am almost 30 and just started a tomato garden in my first home. I hope I find a fat, green horned worm:) sooner than later...

    Lucky kids in your classroom!

    Lucky kids in your classroom!

    They are very lucky kids in

    They are very lucky kids in your classroom. I have hornworms on my tomatoes but I think you are doing a great job teaching these kids!!!!

    I have done this with my

    I have done this with my kids. When it is time, the caterpillar needs to dig into dirt to form its cocoon. I was surprised to hatch 16 large flies instead of the moth! Fortunately, they were in an aquarium!!!

    Growing tomatoes in a

    Growing tomatoes in a container" the plant box" first time in sev. Seasons for us. In louisiana using 'heat-resistant' tom. Var.good flavor!!! Thanks for great info on hornworm...we thought damage was being done by these little orange guys w/ black legs ~ 20 that hide in a group on cool side of one tomato, on the far side of container fr my two spectacular horn worms on other end.,will use light trick tonight to find more of these green rascals. Now to find out about the orange bugs...thanks FarmersAlmanac. My husband and i are from different generations of gardening., ya'll have restored peace in our garden and marriage.

    I have a hanging Topsy Turvy

    I have a hanging Topsy Turvy and found three of these monsters have eaten everything. I was trying to figure out how they got there but apparently they hatched on my plant.

    The little black bugs with

    The little black bugs with orange bodies and black legs that hang out in groups of 20 or so on the underside of the leaves are milkweed assassin bugs. They're kinda awesome. You're seeing them before they're fully grown. As adults they will assassinate garden pests and suck all the body fluids of their prey. Unless they're just milkweed bugs. If they remind you more of ants, like little soldiers, they're assassin bugs and safe to keep around.

    I'm battling the horned worm

    I'm battling the horned worm as well but this morning found them on my milkweed plant! I've been waiting and waiting for the monarchs to lay eggs but instead an infestation of horned worms! I'll go out and get rid of them now that I've seen a pic of the monarch worms and know that's not what's on my plant! Gardening is such work and I'd like to eat my egg plants growing and not feed the worms!

    What can you tell me about

    What can you tell me about these guys all over my lawn in Albuquerque for the past week? They are about 3" long and eating the grass and/ or spurge on my lawn. They are yellow with red and black spots with a stripe down both sides. Wish I could include photos...

    I draped bird netting over my

    I draped bird netting over my plants to keep the birds off the tomatoes and chilis, and found it has the added advantage of keeping the tomato worms away. The mesh is big enough to let the pollinating insects through, but keeps the large Mandunca moths out.

    Now that gigantic green worms

    Now that gigantic green worms ate all of my lovely tomatoes my grandson found a huge worm in the soil After I had remove the destroyed plant. So my question is. Can I plant some other plant in this same soil and Not have these creatures destroy??

    Tomato hornworms are the

    Tomato hornworms are the scurge of tomato growers. The larvae burrow into the soil to pupate and emerge next spring as a moth. You can plant in the same soil—but not plants of the same famiy. Practicing crop rotation, as well as introducing natural enemies (parasitic braconid wasp, for example) can help to relieve the problem.
    Some folks suggest that growing your tomatoes in containers can minimize the presence of hormworms. Remember, too that crops in containers (or the soil used) also should be rotated for best results.

    Forget the idea that

    Forget the idea that containers are safe zone, I planted 2 patio tomato plants and I have a hornworm invasion.

    I also had a patio tomato

    I also had a patio tomato plant up on a deck and it too has got a hornworm. It is so gross and has devastated the only productive tomato plant that I have. Bad year for tomatoes

    I also container planted

    I also container planted tomatoes in an screened in patio. This morning I removed two hornworms. Not having the heart to kill them, I removed them out to my yard. The more I read, do I really have to kill :(

    Pages

    FREE BEGINNER'S GARDEN GUIDE!

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

    The Almanac Webcam

    Chosen for You from The Old Farmer's Store