Are you looking for ways to deter or repel hornworms? Or are you seeking a guide on how to get rid of hornworms completely? Either way, this article will help you.
Notorious for devastating crops and plants, hornworms are true nightmares for farmers and gardeners. If you have a vegetable garden or an agricultural farm, you’ll likely encounter these green pests at least once.
Hornworms are voracious eaters and need only a couple of days to destroy a plant completely. These relentless pests can eat up to 4 times their body weight every day.
Thankfully, getting rid of these garden pests isn’t too hard. There are several ways to repel them, ranging from the manual removal of the pests to chemical treatments.
Should I Kill Tomato Hornworms?
As much as you might hate killing insects, you don’t have much choice when it comes to tomato hornworms attacking your plants.
Remember, tomato leaves are not the only thing tomato hornworms munch on. They feed on a variety of other vegetables, too, including eggplants, potatoes, celery, etc. The nightshade plant species are particularly prone to hornworm attacks.
Ignoring a hornworm infestation in your garden can make all your work on the plants go to waste. As long as the garden has plants it can feed on; these garden pests will wreak havoc.
The same goes for a tobacco hornworm infestation. You need to kill them as soon as you can. You can easily locate hornworms by looking for their black droppings on the plant’s leaves.
How To Get Rid of Tomato Hornworms Without Pesticides?
Gardeners often refrain from the use of pesticides, which is indeed sensible. Considering the potential side effects of pesticides on beneficial insects, they should be a last resort when natural methods fail. Let’s explore how to get rid of hornworms naturally:
Handpicking the hornworms off your plants is the simplest way to remove them. You may either feed the handpicked hornworms to birds or simply kill them yourself.
You can easily identify tomato hornworms – they look like green caterpillars with black horns and white V-shaped markings.
2. Beneficial Insects
Releasing natural predators in your garden is an effective long-term strategy to deal with hornworms and other pests that can damage your plants or crops. Ladybugs, lacewings, and parasitic wasps are some of the beneficial insects that kill hornworms.
Parasitic wasps such as paper wasps and braconid wasps use hornworms as hosts to lay eggs. Once the eggs hatch and the baby wasps grow through the larval stages, they feed on the hornworm’s body and ultimately kill it.
3. Predatory Birds
Having more birds in your garden is a good idea not only for the ambiance but also because the birds feed on pests. Some birds, such as Baltimore orioles, downy woodpeckers, flycatchers, bluebirds, and sparrows, are voracious hornworm eaters.
Setting up birdhouses, birdbaths, and bird feeders in your garden will invite more birds and help keep the hornworm population under control.
4. Plant Trap Crops
As an alternative to handpicking the hornworms, you can use trap plants to draw them away. Take a nightshade plant and place it near the plants infested by hornworms.
Once the pests move to this trap plant, you can kill the pests easily or dispose of the plant altogether. Tobacco plants are particularly good for trapping hornworms.
5. Plant Dill
Like the other trap plants mentioned earlier, dill helps draw away the hornworms. However, it deserves special mention because dill also attracts predatory insects that kill hornworms. This makes it very effective at trapping and killing hornworms naturally.
6. Floating Row Covers
Installing floating row covers or high tunnels over your plants will bar hornworm moths from reaching them at all.
This way, you don’t have to worry about the moths laying hornworm eggs on your plants, which could hatch into hornworms and cause an infestation. Remember to remove the covers in time for pollination.
7. Ground covers
You may also cover the ground around your plants with a layer of black plastic mulch.
Once the hornworms pupating in the soil mature into moths, this ground cover will prevent them from coming to the surface. They’ll die without being able to lay eggs for a new generation of hornworms.
8. Use Companion Planting
Companion plants like basil, borage, parsley, and marigold repel hornworms. Some companion plants also attract pollinators and insects that prey on hornworms. Interplanting companion plants in your garden will aid in pest control.
9. Crop rotation
Rotating your crops is always a good idea, for growing the same crop on a patch of soil repeatedly can drain the necessary nutrients from the soil.
However, it also helps control hornworm populations by removing pupae in the soil, burying them too deep, or simply making it harder for the moths to find the crops.
10. Till the soil
While pupating in winter, hornworms may hole up in the soil. Overwintering in the soil allows them to pupate safely. By spring, the pupae will mature into adult moths and fly off.
This is why it’s a good idea to till your soil after a harvest. Do this at the onset of winter because it exposes the hornworm pupae to cold weather and kills them.
11. Spray Homemade Cayenne Pepper Spray
Natural homemade insect repellants like cayenne pepper spray are a great alternative to chemical pesticides. Spraying it on the plants will repel hornworms and might even kill them. You can make the spray using water, cayenne pepper, and soap.
12. Neem oil
Neem oil is one of the most effective natural pesticides, but does neem oil kill hornworms? Yes, neem oil is very good at killing hornworms, but it can also kill other beneficial insects. Try neem oil only as a last resort before switching to chemical pesticides.
How To Kill Tomato Hornworms With Chemicals?
In case you’re dealing with a large-scale hornworm infestation, and the natural methods fail to get rid of these green worms, you may have to resort to chemical pesticides.
Choose your pesticide carefully and use it in carefully moderated amounts. Two of the most effective pesticides you can use to repel hornworms are:
1. Bacillus Thuricide (B.T.)
More commonly known as B.T., Bacillus Thuricide is a natural chemical obtained from Bacillus Thuringiensis, a soil-dwelling bacterium. B.T. is an excellent insecticide that kills pests by paralyzing their digestive system. The hornworms eventually stop eating and die.
B.T. also deters cabbage loopers, cabbage worms, and other caterpillars. Moreover, it is safe to use as it doesn’t harm humans, kids, or other animals.
B.T. is not quick acting. You have to apply it several times for it to work. It’s less effective in sunlight and dries off quickly, so it might be a good idea to apply it at night.
2. Monterey Garden Insect Spray
Like B.T., Monterey Garden Insect Spray is a biopesticide made with the help of bacteria. It contains Spinosad, which is highly effective for pest control.
Using Monterey Garden Insect Spray will help you quickly and effectively eliminate the hornworms. Besides tomato and tobacco hornworms, this pesticide is also effective against moths, flies, borers, butterflies, leaf miners, caterpillars, etc.
Mix Monterey with water as per the specifications on the label. Spray it on both the top and bottom of the plants. Make sure only to mix as much spray as is needed for one use. This insecticide is harmful to bees, so don’t use it on plants that are pollinating.
How To Prevent Tomato Hornworms
Of course, it’s better to prevent a tomato hornworm infestation altogether than work on repelling the pests later. There are various preventive measures that you could try out to protect your plants from these pests. Let’s check out some of these.
1. Try Diatomaceous Earth
Diatomaceous Earth (D.E.) is both an insecticide and a repellant. Sprinkling this powdery substance on and around your plants will help deter hornworms.
Diatomaceous Earth has the texture of broken glass and can easily shred the small bodies of these pests. Once the D.E. enters their bodies, it will cause them to dry up and die from dehydration.
2. Use Black Plastic
This method is similar to the use of black plastic mulch as ground cover. By laying sheets of black plastic over the soil, you can trap the pupating moths in the soil and prevent them from getting out.
Eventually, they’ll die before even getting a chance to lay new eggs. You may also use a thick layer of cardboard as an alternative to black plastic.
Frequently Asked Questions
Will Soapy Water Kill Hornworms?
Yes, soapy water is also effective at killing hornworms. Moreover, a soap and water solution won’t harm bees and other beneficial insects in your garden, which makes it a better option than insecticides. Alternatively, you may also use insecticidal soap for this purpose.
What animal eats hornworms?
A variety of small insectivorous animals, like chameleons, leopard geckos, bearded dragons, scorpions, spiders, etc., feed on hornworms.
Hornworms have a high calcium and moisture content, so they are healthy food for most smaller insects and animals. They are low in fat and also have a decent amount of protein.
Where do hornworms go during the day?
During the day, hornworms hide beneath leaves. Their green bodies are perfect camouflage and allow them to blend in with the leaves. They come out in the evening to feast on plant leaves and are much easier to spot at twilight.
Will tomato plants recover from hornworms?
Yes, even if your tomato plants have suffered a hornworm attack, they will likely recover. You may help stimulate new growth by pruning the damaged branches and leaves. When you remove the leaves, the plant will produce new ones quickly from the existing leaves’ axils.
Despite their dreaded reputation, you can easily get rid of them and protect your plants from future infestations. It’s best to remove hornworms before they can mature into hawk moths ( also known as hummingbird moths)
Hawk moths would lay more eggs in the hundreds, and those can hatch into new hornworm larvae very quickly, leading to a full-blown infestation. Thank you for reading!
Over the years, our readers have sent us several emails on this topic. Please go through them below.
Letter 1 – Hornworm of a Leafy Spurge Hawkmoth from Canada
Subject: Caterpillar possible sphynx
Geographic location of the bug: Brandon Manitoba canada
Time: 02:04 PM EDT
Your letter to the bugman: Hello, I can’t fond this guy in my books. Yellow stripe down the back with white spots surrounded by black. Horn on tail.
How you want your letter signed: Angela
These are Caterpillars of the Leafy Spurge Hawkmoth, Hyles euphorbiae, and according to Sphingidae of the Americas: “The leafy spurge hawk moth, Hyles euphorbiae (length: 2-3 cm, wingspan: 5-7 cm), was the first classical biological agent released against leafy spurge in the United States, with approval for introduction granted in 1965. Populations of this insect are present in several western states, including Montana, Idaho, North Dakota, Wyoming, Minnesota and Oregon, and now Washington (Spokane County; David Droppers; BAMONA). The moth was also introduced from Europe into Ontario, Canada, and then into Alberta where specimens are occasionally still taken. I recently received an image of larva (July 2003) from Neepawa, Manitoba.” Here is an image from BugGuide. Often knowing the plant upon which a caterpillar or other insect is feeding is a tremendous assistance for identification, and the image of Leafy Spurge on Idaho Weed Awareness is a perfect match for the plant in your image.
Letter 2 – Rustic Sphinx Caterpillar Parasitized by Braconids
Subject: Parasites On Tomato Hornworm
Location: Tampa, Florida
September 22, 2013 5:17 pm
Dear What’s That Bug,
We are HUGE fans, for many years. Here is a great shot we though you’d enjoy! We sure enjoyed watching the bug show!
Signature: Bug Love, Ana & Cory
Hi Ana & Cory,
This is definitely a parasited Hornworm, and the parasites are Braconids, however, we do not believe this is either a Tomato Hornworm or a Tobacco Hornworm. The caudal horn does not resemble either species and the caterpillar appears to be feeding on some plant other than a member of the family Solanacea. Compare your caterpillar to the images of a Tomato Hornworm or Five Spotted Hakmoth on Sphingidae of the Americas, and to the photos of a Tobacco Hornworm or Carolina Sphinx also on Sphingidae of the Americas. Can you provide the name of the plant for us? That might help assist in the species identification for your caterpillar. Our best guess is that this might be the caterpillar of a Rustic Sphinx. Compare the texture on the caudal horn and the head of your individual to the images posted to Sphingidae of the Americas and to BugGuide.
Thank you so much for responding! I have to admit, that since I’m such a huge fan, I was on cloud nine all day from your nice response. Years ago, when I began college, I was curious about insects, and your site really inspired me to learn more. I learned so much from you. Now I’m a science teacher, and we play with bugs every chance we get, and my students are encouraged to catch them and display them (alive) in the classroom for a few days. You’ve never taught a lesson, until a giant katydid crawled on your (and your students’) arms! Cory is an environmental scientist and a lover of all “bugs” as well. He was also the photographer of this stunning shot.
After your help, we concur that it is a Rustic Sphinx Caterpillar. He/she was on a Beauty Berry, callicarpa americana, that is in my front yard. After research, the beauty berry is a rustic sphinx moth host plant. I can’t wait to share this with my students tomorrow. Unfortunately for the caterpillar (and the Braconids), it was eaten by a bird 🙁
Thanks again for your reply. We absolutely love what you do!
Ana & Cory
Hi again Ana & Cory,
Thank you for your inspirational email.
Letter 3 – Hornworm parasitized by Braconid Wasp Pupae
caterpillar with white sacs
Location: Church Hill, Tn
August 11, 2010 6:17 am
Can you identify this caterpillar found
in my backyard?
Your caterpillar is a Sphinx Moth Caterpillar, commonly called a Hornworm. Since the caterpillar was found on tomato (as evidenced by the name on the photographic digital file), it is one of two species in the genus Manduca. It might be the Carolina Sphinx, Manduca sexta, whose caterpillar is known as the Tobacco Hornworm (see BugGuide), or it might be the Five Spotted Hawkmoth, Manduca quinquemaculata, whose caterpillar is known as the Tomato Hornworm (see BugGuide). The distinguishing features on the caterpillar are obscured by the angle of view and by the pupae of a Braconid Wasp. There are many different Parasitoid Wasps that look very similar, and it is believed that Cotesia congregata may be host specific to Manduca sexta, according to BugGuide. The female wasp lays her eggs inside the caterpillar using her ovipositor. The eggs hatch and the wasp larvae feed on the inner organs of the caterpillar, eventually burrowing to the surface where they form the cocoons visible on your specimen. The caterpillar is doomed from the point the eggs are laid, but it continues to live and feed so that it can provide nourishment for the growing Braconid Larvae. Both the Tomato Hornworm and the Tobacco Hornworm feed on tomato plant leaves.
Thank you for your prompt response to my question. I am amazed at the wealth of knowledge that
can be found on your website. Keep up the good work.
PS I grew up loving bugs and at age 55, I am still facinated by them. I am one of 8 children. My sister, who
is 2 years older than me, hated bugs as we grew up. Since there were always baby food jars at our house,
I would take an empty one and go outside to “catch bugs”. One night, I took the jar with me to bed. I shared
the same bedroom with my sister. During the night, the lid accidentally came off and the bugs were in our bed.
My sister woke up, screaming. The bugs were rolly-polly’s and were crawling in the bed. Needless to say, my mom
ask me not to take them to bed with me anymore.
Thought you might need a chuckle.
Letter 4 – Hornworm of a Pink Spotted Hawkmoth
Subject: Caterpillar eating Morning Glory
Location: Victoria, TX
April 22, 2017 6:14 pm
Hi bugman been a long time fan and have always found your site useful and informative. We have a butterfly garden and love insects. We also do not exterminate and plant sage with our tomatoes. etc. Something ate an entire wall of morning glory and we finally found one. There may be many culprits, (we get excited) but our collection of field guides did not identify him. I appreciate your help and we are so excited about him. Thank you for your knowledge. God bless and we love your site.
Signature: Kristy Mower
This Hornworm is the caterpillar of a Pink Spotted Hawkmoth, Agrius cingulata. According to The Sphingidae of the Americas: “Larvae feed on plants in the Convolvulaceae family, especially Ipomoea batatas (sweet potato) and in the Solanaceae family, especially (Datura) (jimsonweed) and related plants in the Americas. “
Letter 5 – Hornworm from Puebla, Mexico
Subject: caterpiller question
Location: Puebla, Mexico
October 12, 2013 4:21 pm
My nephew is in Puebla Mexico and found this caterpillar. What is it?
We are unable at this time to provide you with an exact species identification, but we can tell you that this is a Hornworm, the caterpillar of a Sphinx Moth or Hawkmoth in the family Sphingidae. If you or your nephew has the energy to search for the exact species, you can start with the Sphingidae of Mexico page of the wonderful Sphingidae of the Americas website. If you find a match, please write back to us with the information.
Here is the response I received from Bill Oehike.
Looks like an unusual color.
Bill Oehlke Responds
I am pretty sure it is Agrius cingulata, the Pink-striped Hawkmoth.
The larvae of this species are quite variable, and I have never seen this particular form before. However, it is a very good match for most diagnostic characters.
I wish permission to post image credited to photographer and sender/finder.
Can you check that out for me and get back to me, also with date and names.
You should also check out Bostjan’s comment on the posting.
Letter 6 – Hornworm Pupa: Manduca species
Subject: White Lined Sphinx Moth?
Location: Nevada, USA
February 28, 2017 6:38 am
Would this be a cocoon or pupae?
My neighbor found it in her garage so I placed in a protected outdoor plant, just barely covered with soil. I live in Las Vegas, NV & it’s Feb 28, with currently 45degree lows. I’ve seen many White Lined Sphinx Moths around here so I’m guessing that’s what I have. Did I do the right thing with it? I’ve also included a photo of a tree in my yard which has white flowers that remain open at night. There are also many wild Primrose plants growing in the desert near me.
Signature: Renee Rhodes
This is definitely a Sphinx Pupa, but is it not that of a Whitelined Sphinx. Your individual has a “handle” that is the casing for the proboscis and that detached casing is absent in the Whitelined Sphinx Pupa that is pictured on Sphingidae of the Americas. We believe your individual is from the genus Manduca that contains at least two species that feed on the leaves of tomato plants and other related plants in the family. See images on Things Biological and Russell Labs.