Tomato Horn Worms
Tomato Hornworms are the larva of a huge moth called five-spotted hawkmoth. Approximate size of the moth is around the size of a hummingbird so you can’t miss them. The hawkmoth is gray-brown with yellow spots on the sides of their body.
Tomato Hornworm-(left) Colorado State University, Five-spotted hawkmoth (right)-Floridagardening.com
The hornworm caterpillars are pretty small at first and hard to see because of their pale green color, but they become huge - 3 1/2 to 4 inches (7-10cm) in 3-4 weeks. You can’t miss them then! They are green-brown colour with v-shaped markings on the body and unmistakable ‘horns’. Hornworm eggs are green and are laid on the underside of leaves.
Hornworm Pupa (cocoon), Hornworm Egg (right)-Colorado State University
Hornworm Lifecycle
The five-spotted hawkmoths lay their eggs as soon as they mate after hatching. They appear in late June to August. Full grown larva (3-4 weeks feeding) wander around the garden digging themselves in where they form a pupa (brown and about 3cm long) that overwinters and hatches in the spring.
Hornworm Damage-Floridagardening.com
Hornworm Damage
Tomato Hornworms feed on leaves and stems of tomato plants. Ocassionally they will also eat the fruits later in the summer months. They also feed on peppers, eggplant and potatoes. They can defoliate a plant in just a few days. There can be two generations of tomato hornworms every year. A bunch of them can spell disaster in your garden!
How To Control Tomato Hornworms
- Use a liquid Bt spray like Green Step™ Caterpillar Control
Bt (Bacillus thuringiensis) does not harm animals, people or the environment. It paralyzes the horn worms and they die from starvation. Spray the top and bottom of the tomato plant leaves. Repeat every 5 to 7 days until you don’t see anymore worms. Bt is safe to use right up to the time of picking your tomatoes. - Another all-natural environmentally friendly pesticide that is safe for use around kids and pets is Plant Guardian™ Houseplant Insecticidal Soap
Spraying the undersides of the leaves with an insecticidal soap mixture kills the eggs at the first sign of seeing the moths. A hard spray of water will also help if your plants are strong enough. Wiping the eggs off with alcohol on a q-tip is also effective. - Introduce Parasitic Wasps into your garden
Parasitc Wasps (Braconid and Trichogramma) lay their eggs on the larva. If you see little white things on the worm don’t kill the worm, place it in a jar with a fresh leaf and keep feeding it until the wasps do their job. These are the cocoons of the wasp and their larva feed inside the host and will kill it. This guy below has just met his maker!
Hornworm with parasite eggs (left)-Joe Boggs, Braconid Wasp (right)-Perdue University - Hand Pick
Tomato Hornworms are so big you cannot miss these guys. If you don’t want to touch them I recommend cutting them in half with the kitchen scissors. In the fall when you turn your garden pick out any pupae (cocoons) you might find and destroy them. - Companion Planting
Plant marigolds as a deterrent around or between your tomatoes. Marigolds stink to a lot of different bugs and they avoid them.
July 19th, 2008 at 6:54 pm
I found my first Tomato worm! Were there is one, can I expect to find more? My plants have never been healthier and bam!! I happen to find one while pinching my ends.
Please help.
Distraught wannabe farmer.
July 10th, 2008 at 10:46 pm
This is my first experience with the tomato worm. I planted some of my tomato plants in the new upside down planters. The rest I planted in large patio containers. I did not see any of the moths that have been described. How did my plants get the worms? I used sterilized top soil and gardening soil.
June 13th, 2008 at 9:20 pm
HELP! I have been growing tomatoes for years and this year I put them in pots. The tomatoe plants grew like crazy and is producing a lot of fruit but…there are brown spots at the bottom of the tomatoe. Weird,huh? I know about the marigold trick and it works very well, also, I use ashes from my barbeque to put on my plants. I thinks it chokes out the bugs. It is organic so I have used it for years. But the brown spots at the bottom of the tomatoe. What is a gardner to do?
May 25th, 2008 at 9:54 am
Another way to spot them is to listen. They will make a clicking sound when disturbed, so I shake and feel around on my plants and listen for them. It’s pretty distinctive, so once you get to know the sound it’s easy to hear.
March 24th, 2008 at 9:02 pm
how do i purchase tomato worms if thats possible my beadred drogon loves them
February 19th, 2008 at 8:22 pm
FYI, Marigolds do NOT “stink” to insects, they actually kill insects!
I worked as a chemist in an insecticide manufacturing plant for several years. I became a toxicologist because of my work there and moved on to another area. One of the things I learned there is that marigolds and a few other plants actually generate a natural insecticide that is very effective in killing many insects, breaks down in only a few hours and has a very LOW toxicity to humans and animals. This IS a very effective and safe method of insect pest control AND it tends to discourage many Animal Pests because the plants DO “stink” to them and may cause the plants they want to feed on to taste bad, but that is speculation. Even if Animal Pests DO invade your garden, they are unlikely to be seriously harmed by this because they are most likely to come at night when the marigolds are least active in secreting their natural insecticide AND they would probably have to consume several times their own body mass in garden greenery to get enough natural insecticide to actually be a lethal dose. It’s very unlikely that ANY rabbit or deer is going to be able to do THAT! =^_^=
I would STRONGLY urge anyone who uses the companion planting method to wash their vegetables thoroughly with soapy water before eating any of them! No sense in taking chance with your children or loved ones or yourself. Be SAFE and Sensible. =^_^=
January 30th, 2008 at 12:54 pm
Thanks for a great site.
Since moving to Maine three years ago, I’ve tried to plant tomatoes. Each year the plants (50 of them) have been totally destroyed by these worms. Finally, I know something about them. I finally know that they come from the Five Spotted Hawk Moth. I’m searching for a good picture of this moth.
I’m going to give the tomatoes one more try this year with Green Step Caterpillar Control and Black Light at the ready.
Can the green step be used as a soil treatment?
Thanks for all the great information.
November 26th, 2007 at 10:05 pm
Your site was very helpfull, but man some of the people that have asked questions here must be very stupid.
I think that read about 10 variations of the same question and I am sure that there are more. Look people, search before asking questions because your question might have already been asked.
October 31st, 2007 at 12:12 pm
This has to be one of the most delightful sites - re Hawkmoths and tomato worms that one could ever wander onto. I cut open an heirloom tomato last night and found two green worms in it..and somehow just had to know more, wanted to keep them. seems I am not alone! Question - is it better to try to let them live indoors, cocoon, hatch…but its winter almost now..NYC…so then what? or would it be better to let them go to soil outside on fire escape in a clay pot with soil, and a few tomatoes?
thanks for getting back to me. and thanks for this wonderful site and all the great postings.
Patty
October 24th, 2007 at 3:50 pm
We found some tomatoe worms on our plants and would like to keep them for my grand children to watch… should I put dirt in the bottom of the container and when do they go under ground for winter? How long till they come out? Do they turn a brown color while still feeding? The largest one we have is turning colors? Your site has been very helpful and after 20 years now(second gneration of children) I really know where they come from. ha thanks