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 1st, 2009 at 6:38 pm
To the person who says “horned worms help to “prune” the tomato plant and keep them from getting too leggy or consumed in Plant production” I say…ARE YOU CRAZY?!? I have beautiful 5 foot tall tomato plants that as of last week are almost destroyed due to the lovely horn worm. So you go ahead and keep up your bed and breakfast for bugs and I’ll send them your way. I will be happily trying some of the above mentioned remedies so my family can have a chance to eat the tomatos that we have so carefully tended to over the last few months.
June 30th, 2009 at 9:14 pm
For all of you folks who have to kill insects… remember that they have been placed here for a purpose. I have found and my grandfather before me told me that horned worms help to “prune” the tomato plant and keep them from getting too leggy or consumed in Plant production. In fact a good gardener will prune out some of the tomato plant growth to help grow the tomatoes. What I usually do is relocate the horned worms to various plants and let them have at it. Ok, ok if they get a bit carried away, I have removed a few but we always look forward to seeing them in the garden and even the moths!!
PS to the guy who lives in Florida - if you can’t stand the heat in the kitchen, get out and quit your complaining. Florida is/was a swamp and should always be. I liked your idea of going back to New Jersey.
June 30th, 2009 at 2:42 pm
Saw 7 between two plants this morning, have then in a bucket with leaves from plants and threw in some lettuce we had from dinner last night. Ive seen different suggestions from this site on how to bury them as a science experiment, how can we do this safely for them? How big do they need to get before they go into the soil. How much soil?
We don’t want to dust anything on the plants for fear of hurting them or our food source, how can we keep them away naturally.
Thank you
Barb
June 27th, 2009 at 11:31 pm
To rid you garden of the…plan carrots right next to your tomato plants! Carrots repell them!
June 17th, 2009 at 6:59 pm
I don’t have any tomato plants, but these little guys are eating all my flowers. I planted them a month ago and one day I walked out there and I thought they were little catapillers. My husband corrected me and said that I need to kill them right away. I used the marigold technique and a pesticide and its work really well! It took them about 5 days to all finally die off but I havent seen one in like 2 or 3 weeks. Thanks to this site for all the help!
June 16th, 2009 at 12:55 am
The first time I saw a moth emulating a humming bird, I was astonished. I had never been aware before, that such a large insect…which at first glance might even be mistaken for a humming bird…existed. Maybe even second or third glance. Are these the full adult forms of the dreaded horned tomoato worms? If so, I have seen them visit peach blossoms and other flowers, and so might be considered valuable pollinators, even if the larvae have a taste for tomatos. But I’m really not sure we are talking about the same thing…?
June 14th, 2009 at 9:13 pm
I’m now saving on fish food. I’ve got two Blood Parrot fish that seem to think the fat little worms are quite delicious.
May 1st, 2009 at 4:42 pm
Boy was I supprised when I looked at my tomato plant today (what the heck is that?) I replied to my wife. Yikes there is another one, and one more.They are hard to see but some were about three inches. I quickly put them in a jar to study and tonight I,m going to spray.This is the first summer we have tried porch plants here in Florida,This has always been a buggy place, what’s next??first it was fire ants,carpenter ants,then fruit rats, big roaches(palmetto bugs) huge spiders and so on.Don’t forget the snakes, snapper turtles, otters,rabbits,possoms, gators,ect. that frequent our back yard. I love this place??? should have stayed in Jersey.
April 22nd, 2009 at 9:39 am
My students are doing a science project on tomato worms and I was wondering how we are suppose to keep the dirt while we wait for them to turn in to moths.
February 12th, 2009 at 2:45 pm
Nasty little critters. Beautiful yes, the moths are gorgeous but my kids love to ‘quish ‘em’ into the grass. They absoulutely ruined 20 sq feet of tomatoes last year. In ONE day while we were away, all of our plants were destroyed. I wish we had the parasitic wasp around here! Do not feel sorry for the critters! And as for the science prjects.. good for you! My husband had never heard or seen of these before last year.. and I probably wouldn’t be so grossed out by them if I knew more about them.