The dreaded hornworm. Both tomato hornworms and tobacco hornworms can attack tomato plants in the garden. A single hornworm can wipe out a plant in a matter of hours, and several of them can decimate an entire row of tomato plants in no time!
If you suddenly find your lush tomato plants have become nothing more than stems, most likely a hornworm is the culprit. In fact, it’s a good idea to examine your plants a couple of times during the day, if at all possible, to head off the devastation. They often start near the top of a plant, so the tell-tale bare stems are fairly easy to spot.
The common advice seems to be that gardeners should rotate their tomato crops in order to prevent infestation, since garden soil can harbor the eggs from one season to the next. To be honest, I haven’t found that to be much help. Hornworms showed up the first year in soil that had never grown tomatoes before, and they continue to find my tomatoes even if I move them.
The best way I’ve found to deal with them is to watch carefully for damage. If any damage is seen, start searching for the hornworms. They can be very hard to find, since they are fat and green and blend in perfectly among the tomato stems. During the heat of the day, they are usually hidden on the undersides of stems. Look just below the damaged area and you will mostly likely find them there. I always handpick the caterpillars and destroy them, and follow it up by spraying the plants with BT (Bacillus thuringiensis).
BT is a naturally occurring bacteria that is found in soil and caterpillar guts (so I’m told). When sprayed on tomato leaves, the hornworm caterpillars eat the leaves but can no longer digest, and they die within a day. Damage to the plants is very limited after spraying as well. I don’t use pesticides or other artificial chemicals on the homestead, but BT is not a man-made pesticide. It’s an organic type of control that won’t harm beneficial insects, birds, or other animals and doesn’t leave any residual effect on the tomatoes. It is approved for use in certified organic produce gardens.
In fact, it can also be used proactively. If I’m not going to be able to check on my garden, or if I’ve already started seeing hornworms, I’ll go ahead and spray BT. Check the label since it is mixed differently depending on what kind of pests you are treating. I spray the leaves either in the early morning or late evening (I don’t like to have moisture on the leaves during the hottest part of the day) and from that point on, practice watering only from below. If it rains, it will be necessary to spray more BT.
I bought a bottle two years ago and paid about $10 for it, and it’s still more than half full. A little goes a long way, and it does a great job of protecting against hornworms. Guineas and ducks have taken care of most garden pests for me, but they usually won’t touch the hornworms. I’m told the long horn on the end is a stinger and they can inject a toxin. For whatever reason, the poultry usually won’t try to pick them or eat them, even if I cut one in half and toss it to them. Fortunately my outbreaks are usually limited to no more than a handful of worms at a time, and the BT does a great job of killing any I might miss when picking them off.
(Edited to add — hornworms will attack pepper plants and happily munch them down to nubs too. Since my peppers are usually planted near my tomatoes I keep an eye out for hornworm damage across both areas.)
salutations from across the sea. great blog I will return for more. Ducks for hire
The thing about caterpillars is, when you find and ratocele one, there are dozens that you never see. There may be a captured and ratoceled hornworm still gratefully consuming your volunteer tomatoes, while his stealthier sibs stayed put.Strangely, our Droop Mountain hornworms prefer the wild nightshade and ground cherry that grow in what we euphemistically call a lawn. Only rarely do we get one of these fellas on the tomatoes. If you’ve ever noticed a hummingbird at tobacco flowers just at dusk (or dawn), that was probably one of these big, honkin’ moths. They seem a bit ominous to me they blur the boundary between bug and bird.
You’re more patient than I am, beacsue I couldn’t stand to keep mine on my precious plants (I blogged about the hornworms and parasitic wasps in my garden last week). One thing I noticed, though, I think you have a tobacco hornworm and not a tomato hornworm, based on the red horn and the diagonal stripes. A tomato hornworm is supposed to have a black horn and V-shaped markings. The two are very closely related and feed on pretty much the same Solanum species. Perhaps the distinction isn’t important, but I like to get my names stright.
And in fact, he is still on the volunteers, Rebecca. Or he was yeatsrdey if my husband didn’t drown him too. I wasn’t being completely truthful.And yes about the hummingbird/moths being ominous. But I don’t think I’ve seen a tobacco flower since we stopped renting out our farm maybe ten years ago.We haven’t had this many hornworms for a while. We usually see one or two a year often with the wasp eggs on them. That also is a gruesome sight. But we usually leave them alone the egg-host ones.Interesting about the nightshade and groundcherry. We do have those around. Might be a better place for re-locating, but then that would probably just proliferate our problem next year. Don’t think they’re endangered.
Cool pics. I’ve never seen the entire prsoecs before (mostly because I pick the caterpillars off my plants and throw them into the woods whenever I see them). I have a friend who asked me what these things were on her tomato plants. When I explained it to her, she was completely grossed out; I think it was a factor in her trying to grow some of her own food for only one year. On the other hand, it’s a sad commentary on how far most people have gotten from their food and what’s involved in brining that tomato to your plate…
I’m a little squeamish myself and to be honest, I feel a little — ugh — when I have to smash them. But smash them I do. And it would never stop me from growing tomatoes — I LOVE fresh REAL tomatoes! But the gross factor had me bringing a bucket of water into the garden this year, so I could pick them up and drop them in. They CAN get out by the way, but they may also just drown. But it was easier for me to kill them that way.
Sounds like your friend was grossed out by the idea that the worms existed at all though? Not sure what to say about that. I know a lot of people who are grossed out at the idea of natural fertilizer. That’s a shame though, since compost and manure are so much better than chemical fertilizers, for the soil, the plants, and our bodies when we eat the produce. You’re right … a sad commentary indeed …
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Thanks for the nice blog. It was very useful for me. I hope you keep sharing ideas like this in the future as well. This was actually what i was looking for, and i am glad I came here!
I had never seen the moths beofre you think I’d'a noticed something that big!
Oh, yeah, you get over the squirmish REALLY quickly when they start eating up your plants.
I will say it absolutely grossed me out when the chickens found a nest of baby mice but then, they took care of a generation of vermin in one fell swoop! High quality protein and all that.
Lola,I missed your last comnemt! Sorry
Do you have a picture of the worm? I may have similar one’s in our garden.Skeeter,Yuck is fairly accurate!Hap,They are very hard to see among the foliage of the tomatoes. These particular worms climbed to the top of the tomatoes otherwise I might not have noticed them. I think the best thing you can do is plant enough tomato plants so that what damage they do can be easily replaced by the other plants.
That is one good thing … they do often climb to the top and can be seen there, but when I search I often find several more that haven’t made their way up the stems yet. When you see one, there are often more. I guess they hatch out together? Not sure about that.
I wouldn’t rely on numbers of plants to get around the hornworms though. I usually plant about 30 tomato plants, and if I miss the hornworms, they can do serious damage to a half-dozen within a couple of days. If you let them go, I imagine they would decimate even a large garden. I could be wrong, I’ve never just left them once I discover them, but I really think they could wipe out 100 plants if you leave them!
The damage is hard to miss though once they get going, and you at least know they are there. The good point is that they become easier to see once they eat everything! If you don’t have a reason to avoid it (such as potential danger to a few other species) I’d recommend the BT at first sign, if you can’t control them with handpicking. This year we had a great variety of butterflies (they seem to be replacing the bees!) so I haven’t used the BT as I did in the past, but it works well and is considered “organic”.
Thanks for the advice. Picked 3 off this morning and 1 a few days ago. First time gardener and my tomato plant in new soil raised garden is about 8 feet tall! Big bumper crop but then this morning an entire stem was gone. When I found the little black crap I usually found one. Marigolds have not deterred these b*****s. But my question is on average how many of these will be found on a tomato plant in one season? Thanks for the help!
Glad you are finding them and picking them off! I’m not sure how many someone else may get on their plants, and it varies a lot for me. Sometimes I’d say I only find a few in a garden with 25 or so tomato plants, so far less than 1 per plant average. And then sometimes I find a lot more. This year was probably the worst I’ve personally had, with probably a total of 40 or so hornworms on about 25 plants, so still less than 2 per plant, on average.
If you have a lot of eggs in the soil though, I’d guess you could expect a lot more. I think it’s possible to plant only one tomato plant and have to pull off dozens of hornworms, so I think the average per plant wouldn’t mean much.
Just keep an eye out for them, and especially watch for damage, so you can control them quickly. Good luck with your tomatoes!
I’ve said that least 4666684 times. SCK was here
Where do you smash them when you picked them off ? I usually squish them under my shoe where i find them. But it seems easier to crush them dead if they are on a hard surface !
Hi Karin!
I did squish them the first year, after unsuccessfully trying to get the poultry to eat them. And yes, it was too difficult to crush them in the garden, since the soil there was pretty well-worked and soft. Believe it or not, I’m a bit squeamish about it though so … I found it a lot easier to have a small bucket of water out there, and drop them in it. Most of them will drown. BUT … there will be a few who don’t drown, and they can actually crawl out of the water if you don’t watch. I carry the bucket to the house after I’m finished, and smash any still living on the concrete in front of the garage. Since most of them are already drowned, I don’t have to smash as many that way.
Thanks for stopping by!
Excellent post. I am having problems with hornworms as well..
i think everyone does a fine job here and just wanted to make that known.
You got a really very good web site, Gladiolus I found it by way of yahoo.
Nasty buggers hornworms. Kill them all lol
Thanks, we had a lot of trouble with these last year. Now I know what to do about the hornworms. Was spraying them with chemicals but didn’t do any good, probably no good for us either!