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Credit: Colorado State University 
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EmailHere are tips on how to identify, eliminate, and control tomato hornworms.
What are Tomato Hornworms?
If you’ve ever grown garden tomatoes, chances are you have dealt with these green caterpillar pests. They can be found in most any region of the US and can ruin your tomato crop in record time; they also feed on eggplant, pepper, and potato. They can blend in quite easily with the green foliage and feed non-stop, creating spotty and chewed leaves and fruit.
How to Identify Tomato Hornworms
Tomato 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 larvae, stage. They are pale green with white and black markings, plus a horn-like protrusion. (They are not capable of stinging.) The lifecycle is as follows:
- In late spring, large adult moths lay eggs on the undersides of foliage, which will hatch within a week.
- Caterpillar larvae will feed from 4–6 weeks before creating a cocoon for overwintering 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 can be identified by their orange markings. They will then lay eggs once again. More than one generation a year may be possible in warmer climates.
The larvae blend 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:
- Look closely at the TOP of your tomato leafs for dark green droppings left by the larva feeding on the leaves. Then look at the underside of leaves and you'll find a hornworm.
- Look for stems missing some leaves and wilted leaves hanging down. You may find white cocoons and their hornworm hosts nearby.
How to get rid of 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.
- Handpicking is an excellent tactic for control if you have the time and patience, or a small garden. The caterpillars are not dangerous and cannot sting. Don't crush the worms; drop into soapy water and they're done.
- Keep wasps around; they're "good" insects which feed on hornworms and act as a biological control. You may see hormworms with wasp larvae attached, which look like grains of rice. (See photo above.) These attacked hornworms will have little effect on your plants, so leave them and let the wasps carry out their lifecycle.
- If the hornworm population or the area of your garden is too large, insecticides can be a useful control. You can use the botanical Bt (Bacillus Thuringiensis), which is a bacterium that acts as a stomach poison (but doesn't harm other plants or animals). Please check with your local Cooperative Extension for a list of approved insecticides in your area.
- To keep hornworms away from your tomato plants next year, try interplanting dill; marigolds are also an excellent companion plant that keeps many pests away.
Comments
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!!!!!
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.
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.
Planting borage among tomato
Planting borage among tomato plants is a good deterent to hornworms as well.
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.
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 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?
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!
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 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 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.
I decided to plant dill
I decided to plant dill between my tomatoes this year and while the worms are back, they seem to like climbing the dill more and are much easier to spot. I have tried most methods for ridding my garden of them but being diligent and hand picking them works best. Get a good flashlight and go out a few hours after the sun has gone down. Best of luck!
I prefer Seven and old
I prefer Seven and old fashioned hand pluckn to remove those sob's. So best of luck in your garden.
If soapy water will take care
If soapy water will take care of the worms when placed in it will it take care of them if I spray soapy water directly to the plant? Thanks
Yes, but don't overdo it. A
Yes, but don't overdo it. A few drops in a LOT of water. Specifically: Mix 1 teaspoon of clear liquid dish soap in 1 quart of water to make an insecticidal soap. Spray just when you need it--and spray in early morning or late evening-or it will burn your plants.
I have tried every method the
I have tried every method the reader above have suggested for the last 10 yrs. None of them work except for 7 dust, and pluckin em off and giving them to the chickens. (they appreciate the ugly sobs)
I have been gardening and
I have been gardening and growing tomatoes for years. This is the first time I have seen one of these owful worms and by the time I found it it had destroyed my tomatoes and eaten nearly all the leaves on two plants. This thing was as big around as my thum and about 4 inches long. I pulled both plants out and tossed the whole thing since I didn't know what it was or if there were others lurking around. I have never ever seen one of these on my plants before. Now I will be buying tomatoes until next summer.
We had 4 of these worms on
We had 4 of these worms on our plants this year and I had never seen the wasp eggs on them in the past so I assumed they were their own offspring. They were completely covered with them. If I had known what they were, I wouldn't have thrown them in the firepit. Worked good to kill them! Next time I will just let nature take it's coarse and let the wasps hatch.
I'm a novice gardener with a
I'm a novice gardener with a few herbs and tomatoes in my front yard.
I'm surprised to hear about these plants that are supposed to keep the hornworms away. I have a very small garden and it contains one cherry tomato plant, along with two basils and two rosemarys, among others.
I first noticed that some of my lower and inner leaves were wilting and dying, but I thought it was because I have to rearrange the plant pretty often to support it. It wasn't until today that I saw some stripped branches and huge hornworms. Now that I look at it, it seems like almost all of the inner leaves and up to a third of the outer leaves have egg pouches on them! What can I do? I don't want to kill bees, as they're the ones making my tomatoes possible. Is the pesticide the right choice for me?
Most of the worms I found were parasitized, but it seems like there are too many for them all to get that.
Thanks for your help!
~CarolAnn
Hornworms usually start at
Hornworms usually start at the top of the plant, eating interior leaves. Handpicking is probably best, since you have a small garden. Use gloves to grasp them and drop them into a bucket of soapy water or, if you can stand to, squish them. Gently scrape the eggs off the leaves and destroy them. If you can, it’s good to leave the parasitized hornworms alone so that the braconid wasps can hatch from the eggs; the caterpillars will die at that time. If this doesn’t work, BTK (Bacillus thuringiensis subsp. kurstaki) can be sprayed on smaller caterpillars; it will not affect bees.
Thank you for the
Thank you for the info!
~CarolAnn
so if i understand this
so if i understand this correctly,if i have found 2 hornworms,chances are i will find many more?? i have never had this problem before in my garden,could they have been in the siol of the plant when i purchased them?
Hi, Nancy, Thank you for your
Hi, Nancy,
Thank you for your interest in The Old Farmer's Almanac.
To answer your first question, yes, it's certainly possible that you will find more hornworms in your garden. Watch to see if the leaves on your tomatoes "disappear" (get eaten) and for black "droppings" (poop). You might even find that bites have been made in your tomatoes.
As to whether they came in the soil, we can only offer a maybe. Just because you never had them before doesn't mean you'll never have them. Eggs are deposited on plant leaves and the mature larvae drop off into the soil at maturity. They dig into the soil where they form a pupal cell before attacking the plant.
Sources suggest that tillage can eliminate as much as 90% of the larvae. So can crop rotation.
One thing to note: if you see a hornworm with a lot of little "white things" on it that resemble grains of rice, let it live! The white things are parasites that will kill the worm and grow/emerge to become predator wasps.
I hope this helps!
I seem to get these SOBs
I seem to get these SOBs every year. Have done everything from seven to plucking them off. I HAVE discovered that if they have stripped a branch of leaves and you pluck off the worm that the leaves WILL grow back and they CAN produce after that. Now that I know what the Moth that starts this crap looks like I can KILL the MOMS and DADS of these dang things. Side story. I have two container pots of tomates that I have brought in for the season, and I am getting tomatoes from them. Imagine my surprise when I found TWO of these SOBs on my INDOOR TOMATOS! That SAME day I found a HUGE moth in the kitchen, across from where the plants are. We took it outside. If I had known then that THIS was the MOTHER!!! I would have killed it and been done with it. Noooo I let it LIVE! "I'll get you next time you ugly!"
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