If you’ve raised tomatoes for any length of time, you’ve probably experienced the devastation of the Tomato or Tobacco Hornworm. I originally thought that I was dealing with the Tomato Hornworm (Manduca quinquemaculata), but truly, the caterpillar that is defoliating my tomato and tomatillo plants is the Tobacco Hornworm (Manduca sexta). The two are very closely related and can both be found on the same plants, primarily members of the family Solanaceae (tomatoes, peppers, eggplants). You can distinguish them by appearance: the Tomato Hornworm has eight V-shaped marks on each side and their horn is straighter and blue-black in color, whereas the Tobacco Hornworm sports seven diagonal white lines on the sides and a curved reddish horn (below).
Your first clue that you have a tomato or tobacco hornworm problem will likely be checking on your tomato plants. Instead of finding beautiful, lush green foliage, you may be greeted by this sight:
Look at that defoliation! No wonder! Tomato and tobacco hornworms can grow to 4 inches long! You might also find their poop on your plants:
If so, look closely, particularly on the underside of stems, because there is probably one or more of these eating machines lurking on your tomato plants!
Luckily, adult tomato and tobacco hornworms are very easy to control by handpicking. I check my tomato plants twice a day (dusk and dawn are the best times to look), hand pick the caterpillars off my tomato plants, and feed them to my chickens. There is nothing more entertaining than watching a flock of chickens fight over a four inch long caterpillar! If you don’t have chickens, simply crush the caterpillar, or drop it into a jar of soapy water.
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I’ve always heard from relatives that Marigolds repel Hornworms but in the book “Carrots Love Tomatoes” it actually specifies “Pot Marigold” being the deterrent of Hornworms. Garlic agrees with Tomatoes as well and repels many bad insects. I normally plant garlic cloves and Marigolds with my Tomatoes to help with pest control. I haven’t had a Hornworm so far so it seems to be working. I know companion planting doesn’t always work when there is a pre-existing problem but sometimes it does help prevent problems. I am going to enjoy reading your blog!
Thanks Marissa! I have been getting such good tips from readers. I think my real problem is that this is a first year garden, so I have not had a chance to really build the soil health in the way that I’d like. I like to plant a very diverse garden, including lots of onions, garlic, and flowers – it always seems to help!
My experience has only been with tomato hornworms, but I think the control options should be the same for tobacco hornworms. Since the rate of plant damage increases geometrically as the worm gets larger, it’s crucial to find them when they’re about an inch long or so.
Of course it’s much, much harder to spot the small ones than the big lunkers, so here is what I do. Lay an old white sheet section, light-colored fabric or white plastic under each plant. These help to show their droppings, especially the smaller ones. Once you see this, you can zero in on the tomato vines directly above. One thing I find is that they often move to uneaten areas to rest, since this helps with concealment. Seeing droppings under an otherwise healthy-looking part of the plant is a clue to hornworm presence. And even if you can’t find any, it will be the first place you look every time you walk by.
Another thing I do is cut off the defoliated parts so there’s no confusion over new damage and old. This also makes it easy to remove the beast without having to wrestle it off the branch. Our chickens loved hornworms and hung around the fence every time we were in there checking. I imagine the size of the things startled your new young chickens, but with time they should develop at taste for them and be right there cheering you on with your searches.
Finally, as was mentioned earlier, these hornworms also love pepper plants, so keep an eye on them as well!
This is all fantastic information, Ron. I might have to share your thoughts with readers in a future blog post!
Baker Family says
I didn’t even have to see the pictures to know what you were talking about. I saw “horn” and “worm” and immediately thought of dead tomato plants. I always take a stick and pry them off the plant, step on them, and then look for the white eggs they’ve laid so I can kill them too, but I’m always just a little too late. They can eat half a plant in just a few seconds it seems. Did they get all of your tomato crop, or were you able to save some of them? I hope you’re able to get everything you need in spite of the hornworm’s attempt to take over. Best of luck!
I was able to save most of them, but several of my plants, particularly the cherry tomatoes, were really hit hard. We picked off a dozen one morning and that seems to have slowed them down a bit, although I remain vigilant! Our tomato crop will not be large this year, but at least we can make fresh salsa!
Oh wow! Thanks for sharing…we just had our first run in with the hornworm last week. We thought it a Tomato, but we’d never heard of the tobacco hornworm! I’m going to have to look more closely, because now I can’t tell what we have!
They look pretty similar, and the damage they inflict is pretty much the same! They are same genus, just a different species. But they both like tomatoes!
Ed Brown says
Teri, Hornworms are common here and I have dealt with them every season I have grown tomatoes or peppers. First, you can repel the moths that lay their eggs on the plants by hanging a large sachet of mint or lavender above the plant. 1/4″ mesh net or screen around the plants also works and intercropping with basil seems to help. The moth does her work at night, and if you are out with headlamps you might swat some down with a badminton racket (which you should have on hand for cabbage loopers)! When you notice the first signs of infestation, look for the clusters of white eggs under the leaves and destroy. If you spray water on the plants in a misting fog, you may hear the caterpillars making a clicking sound and locate them. There are sprays with Bt available and I have had success with them in a heavy infestation, but Bt should be applied every few days. Good luck
Good to know, Ed. I’ll look for the eggs under the leaves. I have been looking for adults, but didn’t think about turning over leaves to find the new eggs. Ah, gardening was so much easier in Oregon!