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Tomato Hornworms
How to Identify and Get Rid of Tomato Hornworms
How to Identify and Get Rid of Tomato Hornworms
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 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 eggplants, peppers, and potatoes. They can blend in quite easily with the green foliage and feed non-stop, creating spotty and chewed leaves and fruit.
Tomato 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.
- 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 will then lay eggs once again. More than one generation a year may be possible in warmer climates.
Tomato hornworm moth (female). Look out for the moths in late spring. Photo by Didier Descouens/Wikimedia Commons.
Identification
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 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!) The caterpillar also has eight V-shaped stripes on its green body. Tomato hornworms come from a mottled brown-gray moth.
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:
- Look closely at the TOP of your tomato leaves for dark green droppings left by the larvae 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.
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.
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 have tomato hornworms. The fruit also might be damaged by sunscald because of the reduced foliage.
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 cannot sting. 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 a useful control. You can use the organic pesticide Bt (Bacillus thuringiensis), which is a bacterium that acts as a stomach poison on some insects (but doesn’t harm other plants or animals). Please check with your local Cooperative Extension for a list of approved insecticides in your area.
A tobacco hornworm covered with parasitic wasp eggs.
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; they’re 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.
- To keep hornworms away from your tomato plants next year, try interplanting dill or basil; marigolds are also an excellent companion plant and keep many pests away.
See the Almanac Garden Pest and Disease Library for information on all your common pest problems.
Plants Affected
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Reader Comments
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Where the Hornworm eggs are
This is my 4th year growing tomatoes. Tomato Hornworms are a problem every year. I am determined to be their nemesis. We use tomato cages and the moths often lay their eggs on leaves near the metal of the cage. I suppose they use the cage for support sometimes. The moths can be largish and the metal of the cages offers more support than tomato leaves. The eggs are usually on the underside of the leaves, but not always. So looking for eggs near the cage metal can be quite productive. Rolling eggs off of a leaf is usually fairly easy and considerably less gross than dealing with the hornworms. Of course, the moths lay elsewhere, so keep an eye out for telltale damage. Cheers!
Hornworms
Do you step on them?
Has anybody tried netting?
I plant tomatoes in large containers on my back deck, and will try netting over each plant to hopefully protect the moths from laying their eggs in the soil. The fact that The Green Menace lays eggs twice a year doesn't help matters. I'll give a heads up if it works.
Attacking my Jalafuego pepper plant
I've noticed this is the first year I've had THWs got them 3 times now on a new jalafuego plant almost destroyed it, grew back just found number 2,3,4. #2 was about an inch long maybe 3mm thick other 2 were fresh hatched worms clear and tinyyy. I can't till because my bell pepper plant is 5 years old and is huge and would love to not destroy it. Anyway add any pepper plant to plants they attack, not just bells sadly :/
companion plants
I have basil, marigolds, and dill planted amongst my tomato plants in my raised bed...still got a hornworm. :(
Not Just Tomatoes
These devils bypassed my tomatoes and ate my potatoes down to the ground, then infested my datura plants. As these are night-blooming flowers, I am not entirely surprised, but pulling them off by hand is harder than you would think. Those suckers are STRONG. I have a small garden, so hand-picking works well, but planting dill only ended up feeding the grasshoppers. Did nothing to deter hornworms.
it's my first year gardening in Alabama after 20 years in Colorado. Takes some time to identify indigenous pests. A bunch of worms the size and thickness of my middle finger springing up out of nowhere? Didn't expect that.
hornworm problem
As I got older I started container gardening in one side of my driveway figuring it would be easier and less pest. Little did I know
these monster hornworms where more at my door step than I thought.They are a real wrestler when it comes to hand removal
so I now use needle- nose pliers to remove .Four Oxheart tomato plants this summer and removed ten of these rascals.
Horn Worms & holes in my tomatoes
I just went out and checked my 4 pots with tomatoes planted in them. I found a bunch of horn worms and actually one big brown worm that looked similar to a horn worm except for color. I picked off the worms I found and pulled them in half and threw them away but I also found that a lot of my tomatoes had holes in them and many of the holes were very discolored. I cut into one tomato expecting to find a worn or something but there was nothing there. Can you tell me what might have caused these holes in my tomatoes?
Hornworms
I bought a blacklight flashlight and go out after dark to look for hornworm. They glow really bright against a black light.
blacklight flashlight
Thank you! Didn't know about the black light! I will give that a try.
Hornworms Tobacco Worms Black Light
Black light at night is terrific. Got 144 worms last year (approx 16 tomato plants). Also look for miniscule green balls on leaves. Kill them all.
Horn Worms
I'm surprised this article did put the best and easiest way to keep horn worms from eating your garden.. Which is planting onions in between your plants whatever they are.... It always works every time....
Tomatoes
What do you think of DE for the pests?
Diatomaceous Earth
Diatomaceous earth (DE) does work against hornworms, though you should only use it when the plant is NOT in bloom. DE will kill pollinators, so avoid using it on or around flowers.
My chickens love them
A time consumer finding them and picking them off my tomato plants, but a tasty treat apparently for my chickens.
Dawn & water solution.
After picking off what worms i could find i sprayed a solution of dawn & water on my tomato plant leaves. Now the leaves are turning brown & the whole plant is looking poorly. Also what blooms there were are falling off. I thought this was supposed to be a safe way to rid the plants of worms. I think i have lost all my tomato plants. Any ideas??
The leaves may have gotten
The leaves may have gotten burnt. You don't want to have wet leaves getting scalded by the sun. Pick off or cut off the brown leaves. See if the plants gain strength.
Hornworm
Do not spray dish soap spray on a sunny day it will burn up your plants recommended for cloudy days
dont use dawn dishwashing liquid
Don't use dawn it is to harsh , if they use it to take oil off of birds etc imagine what it would do to a tomato plant! yikes . I use Thuricide Bt Caterpillar control. I also use pure Neem oil and Dr Bronners Pure Castile liquid soap.
Dawn &Water Solution
I did the same with similar result. Lost several tomato, jalapeno, and Italian pepper plants to the soap mix while trying to combat the worms. I was told later to only use a very small ratio of soap to water. This is my first year gardening so I expected a learning curve. Next time I try this I will do a small test area on a single plant.
Hornworms
I go out after dark with a flashlight and a pair of scissors. I just cut them in half and let the good bugs have dinner on me.
Just one thing if you see a similar looking worm on your dill please don't kill it because it's swallowtail butterfly. I plant dill in various areas of my yard just for them.
Natural prevention
First year growing in containers and hope for a better yield. Last year due to excessive rain when growing in back yard I experienced cracked and bottom rot fruit so I went to containers to allow moving plants to control moisture. For insect repellent I read to mix in a cup of hot water a tablespoon of Baking Soda, oil I used olive oil though something called fern oil is directed and only a drop of dawn dish soap only to emulsify oil into solution for spraying. Once the cup is mixed pour into sprayer with water. Shake well and I always try to use water that has sat dormant for a day or two so any chlorine residuals are dissipated. I love and been growing home grown tomatoes for years and must enjoy the challenge and learning more about gardening because for the time and effort spent over the years it would be cheaper buying them from the local farmers market. Do to the deer, rabbits, raccoons, and birds I now have a potable fencing system.
Blossom-end rot
Blossom-end rot - rot on the bottom of the tomato - could be a result of insufficient calcium in the soil. Crushed eggshells break down and replenish the calcium in the soil.
Calcium
Tried this on my squash this year and very pleased. Crush tums (2 per gallon) and add to a gallon of water...works great to add calcium with very little cost.
Horned worms
These pests devoured my trumpet plant! I picked off at least 15 of them, thinking at first it was deer that devoured my plant. Upon looking further it was these same worms that affect tomato plants! We drowned them then fed them to the wild turkeys. Totally taken aback that they ate my plant! I hate them!
Hornworm eggs
I had those nasty creatures & ended up pulling off what tomatoes I could that were still geeen & hope they ripen in the house or the windowsill. Those nasty eggs(larvae) left my nice new deck with green spots! How do I get rid of the stain without harming my deck? It hasn't been stained yet. Those creatures are gross!
Tobacco vs. Tomato
The pictured worms are actually Tobacco Hornworms. The tobacco hornworm caterpillar has black margins on its white stripes and it has a red horn, the tomato hornworm has green margins on its white stripes and the horn is blue. Just as hungry though!
Hornworms
Is it okay to spray a dawn and water solution then spri lie with cayenne powder on purple Cherokee tomato plants to treat for hornworms?
Dawn & water solution.
I started having a problem with green tomatoe worms so i used a solution of dawn & water to spray the plants. I think it is killing the plants as the leaves are turning brown & the blooms are falling off. They are not looking good. I wouldn't use it.
hornworm
I noticed my tomato plant leaves curling, a week or so ago and attributed it to the Texas heat. It had been many years since I'd had a tomato garden, so I had forgotten all about that 'sign'. I'm hoping the pesky worms have all been located. My question is, will the leaves of my plants uncurl and look full and lush again?
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