Controlling Garden Pests Naturally and Organically

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.

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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.

Tomato Hornworm Pupa (Cocoon) hornwormegg_1.jpg
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.

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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

  1. 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.
  2. 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.
  3. 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!
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    Hornworm with parasite eggs (left)-Joe Boggs, Braconid Wasp (right)-Perdue University
  4. 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.
  5. Companion Planting
    Plant marigolds as a deterrent around or between your tomatoes. Marigolds stink to a lot of different bugs and they avoid them.

512 Responses to “Tomato Horn Worms”

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  1. 512
    Thomas Says:

    I live in central Florida. Just yesterday, I found a tobacco hornworm chewing on my hummingbird bush in my front yard. It caught me by surprise, since I’ve never before found them on any of my 4 hummingbird bushes, and my tomato plants are in the backyard. Where I’ve found one, there were always more chewing nearby. It was easily dispatched with my hedge trimmers.

  2. 511
    debbie Says:

    I have a trapped one…after picking about a dozen off my plants…lol…I have him in an insect habitat…hoping he will caccon soon…is there anything I can do to get him to burrow faster? Keeping him fed takes a lot of foliage…little pig…lol…and what do I need to do to the habitat once he has burrowed? add water or anything? Or just keep it sheltered till spring? (I just want to film it coming out)

  3. 510
    Paula Says:

    These horn worms are destroying my tomato and pepper plants… I leave out in the Palm Springs area of California, so my plants have been in the ground since March 1st. I thought it was grasshoppers but then I saw this huge caterpillar… The reason I noticed them was the poop they leave behind and of course all the leaves were gone….I just killed 8 on one plant – all different sizes and 3 on another…. They creep me out!!!

  4. 509
    Another dreaded garden foe | Says:

    [...] but we did have a crappy tomato crop last year and this could be to blame. The caterpillar/worm causes a lot of damage to tomato plants, mostly chewing through leaves and [...]

  5. 508
    Sami Says:

    melissa luque… if you want to make sure the worm is dead… smash it with a brick. Some people like those destructive critters, and while the Moths they turn into are beautiful, the WORM Destroys gardens. I don’t know about you, but the food from my garden is more important to me that a worm or moth. Good Luck with your garden.

  6. 507
    melissa luque Says:

    i cant tell if my tomatoe worm is dead its getting darker and it still stays bent when you move it. hut it still feels mushy though and i still have a feeling that its still alive but i dont know what to do

  7. 506
    Stacey in TX Says:

    Very interesting to read all the comments of those for and against the horn worms. Our family first noticed the gorgeous huge sphinx and hawk moths hovering around our flowers. They really do look like hummingbirds when you first see them. And of course as moths, they do in fact pollinate plants. We absolutely love those moths–one of the coolest insects on the planet as far as we’re concerned.

    As much as I feel for those of you trying to grow a garden, now that we know that the horn worm (both the tomato and tobacco) turn into the sphinx and hawk moths, we’ll never harm one of those giant green caterpillars. As a matter of fact, we just saved one from a friend who was going to feed him to her chickens. He was great-big and green, so we named him Hulk–naturally enough. He ate about half of a red grape pretty quickly but didn’t seem all that interested in the other things we put into the container for him (wheat germ, dandelion greens, a mint leaf, slice of bell pepper and slice of tomato). And the very first evening we had him (last night), he buried himself under the soil we put into the container. We are looking forward to him coming out in his new duds–and releasing him so that he can pollinate fall flowers.

    Here’s something I read on another site that might give folks a little different perspective–

    “I happen to fall into that category of gardeners who don’t mind the nightshade-eating Manduca hornworms. While one can do some damage to a young plant, here in central Oklahoma, nature sends them late enough in the season, to ensure plants are well-established in their growth and foliage. Since hornworms also find the tender suckers as well as leaves, this pruning is beneficial to force more fruit, less leaves.

    Our Manduca hornworms here are largely endangered, and I do NOT recommend or condone the killing of pupae or moths. We have too many tachinid flies [a non-native parasitoid and responsible for wiping out over 33 native giant silk moth species].

    I strongly advise Oklahoma gardeners to give live hornworms to teachers and home schoolers to rear indoors for education. If a larva dies, it needs to be destroyed as it’s full of tachinid maggots.

    By the way, in your picture of the adult M. quinquemaculata moth, the flower is not a morning glory, but a Datura moonflower. The relationship between the Datura and Manduca’s is completely mutualistic, too. This is one valid reason we need our sphinx [hawk] moths!”

  8. 505
    Anna Says:

    Hi every one!
    I live in Mallorca Spain and this morning I found my first ever Hornworm which was walking across my path in the woods Wilst I was out walking my dogs.
    What a beautiful little creacher it was and I feel lucky to have seen it!
    About tree weeks ago I had the biggest hawk moth (humming bird moth) in my loung which was wonderful to see.

  9. 504
    linda Says:

    i have a huge green worm eating ny lilac bush -i have tomatoes and moon flowers-has anyone ever had a tom worm on lilacs

  10. 503
    bondo Says:

    I found about 10, 2 1/2 to 4′ long on our tomataos. The dear ate the plants, so im going to let them grow and show my children, 2 and 3 1/2, the life cycle. I think they are awsome to look at, next year we will plant plants that keep them away, rather then kill them or hurt them. I try to teach my children to not harm animals, and enjoy the ones you can watch grow. We also have giant praying mantis all over.

  11. 502
    Sm1th Says:

    I just caught a hawkmoth that must have just emerged because his wings were still small. I picked him up and put him in my pet toad’s cage. I couldn’t believe it when my toad hoovered it in about 10 seconds! He is a small western toad, with a HUGE appetite. He can eat about 10, one-inch roaches a night!

  12. 501
    Rose Says:

    The little white things on the horn worm is from a parasite from a wasp. They turn into a pupa, Then next year a beautiful Moth. I did not have any horn worms on my tomatos at all. I have moon flowers. They like the moon flowers.

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