Tomato Hornworms

How to Identify and Get Rid of Tomato Hornworms

Tomato Hornworm
Amanda Hill

Rate this Article: 

Average: 3.8 (648 votes)

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

    I have green worms that eat

    I have green worms that eat everything in the garden, veggies and flower leaves. They especially like morning glory leaves. They are not tomato hornworms. There is no horn, what are they and how do I get rid of them?

    We believe that you have an

    We believe that you have an inch worm problem. You can try to spray with horticultural oils or use Bacillus thuringiensis, a wilt pathogen that is only toxic to insects.

    Kill two birds with one

    Kill two birds with one stone.....with each tomato plant you plant, also plant a basil plant about a foot away. You will not see a horn worm all season and you will always have fresh basil....learned this from grandmother over 50 years ago. Been doing it all my life...trust me it works

    Sorry guys, but I have

    Sorry guys, but I have marigolds and basil in the same pot as the worms. That is not working.

    same here had both marigold

    same here had both marigold and basil planted right under and next to my cherry tomato plants and my plants were destroyed.. help please i have gone out to my raised beds last week as i had some radishes planted there last fall and picked some ,and found live hornworms right under the surface of the soil,this is Feb. and the soil is frozen...what do i do before planting comes

    The pupae overwinter in the

    The Editors's picture

    The pupae overwinter in the soil. Put black plastic on the soil where you are going to plant your tomatoes. This can help prevent the moth from emerging in spring and laying eggs on your plants. The eggs will become the horn worms.

    I live in Maine so if I

    I live in Maine so if I tilled the area I was going to plant in and placed the black plastic over it until it was safe to plant, this would possibly kill the moths? I think sometime in April is possibly when I could till but planting doesn't happen until end of May. Thank you!

    Considering that I do not

    Considering that I do not have tomatoes in my yard; I'm growing three different varieties of basil and hoping to sell them in my local farmers' market, and the hornworms are decimating my basil bushes, I think we can re-evaluate this particular notion of companion planting. I had aphids in my basil, whiteflies too....got rid of them with daily spray of organic soap and weekly neem oil treatment. Both of these I do as early in the morning as possible so the plants don't "cook". The hornworms are a most unwelcome surprise that I'm going to deal with by handpicking.
    I'm going to try woodash on a section and see if that helps. Fingers crossed

    PS. Not trying to discredit you, but I suspect there is something in addition to your basil (maybe wasps or assassin bugs) that's keeping the bugs off your tomatoes. Wish all were as lucky as you and that your luck never wavers.

    This year has been terrible.

    This year has been terrible. I usually plant marigolds but didn't this year..We have taken over 70 hornworns off. I'm sure there are more. They are destroying my 4 tomatoe plants...I have two basil plants next to one of it and that hasn't detterred them at all. I'm wondering is it too late to plant the marigolds this year? The tomatoes are still green what is left. They are heirlooms and I live at 3800 ft. Thanks for any anwers you may have!

    I haven't gardened in years.

    I haven't gardened in years. This year was the first time we purchased three tomato plants from a co-op. When my Early Girl hit 4 ft I noticed leaves missing and there a huge 3" ugly hornworm on the stem (blending in). Since we've never had a garden in the area we planted the tomatoes we were wondering if eggs were in the co-op soil... anyone else had this problem?

    I took the article in OFA to

    I took the article in OFA to heart and planted marigold plants amongst my tomatos this year and we had NO tomato worms at all. I'm assuming it worked, we have ALWAYS had these grose worms and they can devour a plant in short order.

    I do not have any hornworms,

    I do not have any hornworms, but I would welcome them for they are VERY good fishbait. just break them in to two pieces and turn one wrong side out over your hook and bream love them. Sometimes you can catch several fish with one bait.

    Planting borage among tomato

    Planting borage among tomato plants is a good deterent to hornworms as well.

    We have several different

    We have several different tomato plants planted in our garden,only a few have these small "Orange" worms eating on them, does anyone know what they are? Sevin does not kill them either.

    I have found that using a

    I have found that using a strong solution of dish soap and water in a spray bottle works great on just about any pests, no chemicals!

    I used to do that but it

    I used to do that but it destroyed my marijuana plants and my bell peppers too.

    I would like to find "won't

    I would like to find "won't kill bees" product, or alternatives to "Sevin" that really work against hornworms.

    Saving the bees is easy if

    Saving the bees is easy if you have the patience. Simply interplant complanion and compliment plants with your tomatoes: basil, borage, bee balm, dill, and french tall marigolds are best. In addition, plant parsley away from your tomatoes and the hornworms will be attracted to the parsley like bees to pollen. I have thousands of the hornworms on the parsley plants and it is very easy to flick them off into sudsy water. I think I got rid of most of them this year and the tomatoe plants produced thousands of tomatoes with no damage this year. If I had known about parsley last year, I wouldn't have lost my whole crop. Best wishes!!!!!

    PLEASE DON'T KILL TOMATO

    PLEASE DON'T KILL TOMATO HORNWORMS!
    SIMPLY MOVE THEM.
    They become the "precious great" pollinators HUMMINGBIRDS.

    Tomato hornworms... Do NOT

    Tomato hornworms... Do NOT like lavender or rosemary next to their food. We had a BAD infestation on out eggplant, but the tomatoes that were next to the rosemary and the lavender had none. BT works best when the critters are young.

    Diatomaceous earth is

    Diatomaceous earth is supposed to be effective. It must be dry to work. It is safe for bees, animals and humans. Dust it on the plants and soil.

    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