Black Bugs Attacking Tomato Plants

shekanahhJuly 10, 2009

I am baffled by this sudden infestation of large black bugs appearing on my tomato plants. I didn't notice them until late this afternoon when I went to check the garden.

I couldn't identify them by any of the images online, but they aren't a worm, and they don't look like a beetle, or a stink bug. They are about 3/4 of an inch long, and rather thin, and are eating the leaves of the tomato's and leaving nasty looking black "frazz" on the leaves.

I sprayed with Spinosad, and some of them dropped off the leaves but at last check, many were back and munching away and doing quite a bit of damage.

This is the first time I've ever encountered these in my garden, but I guess there's a first time for everything.

Just wanting to warn folks to watch out for these as they seem to be appearing in large numbers, and doing significant damage, seemingly overnight. I am hoping the Spinosad will do them in before they have demolished my otherwise healthy looking plants.


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Upon further browsing online to try to identify these tomato destroyers, I now think they are Blister Beetles.
Now I have to find a control for them! Apparently they are are very destructive garden menace.

Here is a link that might be useful: Blister Beetle Images

    Bookmark   July 10, 2009 at 12:35AM
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Barbara, be very careful. I've crushed them with my fingers, and still do, on occasion. But the juices from their abdomen will cause burns and LARGE blisters on your skin. The best solution I've found is to go through, several times a day, and knock them into a can of water with some oil on the surface. I'd be tempted to try Sevin dust. These are the worst scourge of tomato plants I have ever encountered!

Tahlequah, OK

    Bookmark   July 10, 2009 at 7:18AM
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Okiedawn OK Zone 7


I don't usually have big outbreaks of them here, but I saw one a couple of weeks ago. I haven't seen any since. I don't know of any beneficial insects that eat them either, although I suspect praying mantids might.

I'd think that the most likely organic solution would be neem oil sprayed directly on the bugs themselves more so than on the leaves. There's a citrus-based spray insecticide some organic gardeners use called Sharpshooter that might be effective on them, but I'm not sure I'd spray anything citrus-based on tomato foliage in this awful heat, especially if the tomato foliage is in full sun. Or, if you go the chemical route, either Sevin dust or liquid Sevin. I don't use Sevin myself, but one of my neighbors uses it in his veggie garden and feels it is pretty effective on most things.

Because we have so many grasshoppers this year (the guineas can't keep up with them because the guineas are locked up about 20 hours a day to keep them safe from the cougar), I'm tempted to put up with the few blister beetles we see every year because they prey upon grasshopper eggs. Of course, if I was seeing large numbers of them on my tomato plants, I'd probably be out in the garden with the hand-held mini-vac trying to vacuum them up.


Since I don't like to touch bugs of any kind, you can bet I wouldn't touch one of these. Sometimes I do flick potato bugs into a bowl of soapy water with a finger, but I really hate touching bugs.

I've never had them on my tomatoes. Do they attack the foliage and the fruit? Or, do they only attach the foliage?

Y'all, I've linked J. Howard Garrett's discussion of blister beetles from his website.


Here is a link that might be useful: The Dirt Doctor discusses Blister Beetles

    Bookmark   July 10, 2009 at 9:03AM
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George and Dawn...
I searched high and low on the Internet last night for a control for these voracious plant eaters, and couldn't find any organic controls for them. Dawn, I should have checked Dirt Doctor, but I wouldn't have had the ingredients on tap that he suggested anyway. I did check Dave's Garden, and all he had on his site for Blister Beetles control was floating row covers. Too late for that, and I didn't have those either.

This is my first year gardening organically, which I am still determined is the best way. But still, I didn't want to see my entire tomato crop decimated by these nasty things.

I finally came to one website, which suggested Spinosad, which is what I sprayed them with late yesterday afternoon. When I went out to check this morning, I only saw one or two left on the tomato plants.

The specs on the Spinosad said it usually works in a day or two on most pests. It must be that Spinosad hasn't been on the market very long, but I am thinking that it IS going to work against these pests. I will spray with the Spinosad again today, and try to really drench the leaves good.

On the plus side, I checked my other plants, cucumbers, green beans, squash, etc, and didn't find any evidence of the black nasties on those.

Dawn, they seem to work in clusters on a certain plant, or a "swarm" as it said on the Internet. So, I can see where they'd destroy one plant and then maybe move on to others. In my garden, I saw them working on one tomato plant in particular, and then a few scattered here and there working on neighboring tomato plants. They seemed to just be eating the leaves, and not the tomatos, and then leaving their nasty black "frazz" behind.

Yes, I too am thinking they followed the grasshopper invasion that preceded. It's like they appeared out of nowhere suddenly! So, if other gardeners have seen grasshoppers, maybe they should be watching for Blister Beetles as well.

George, don't worry, I am not inclined to be touching bugs. You never know when a seemingly harmless looking bug may sting the daylights out of you, and I am very sensitive to stings. After reading the take on Blister Beetles, I was sort of worried about my cats eating one of them and getting sick or dying. One silly young tomcat likes to play with and chase any kind of a bug that moves.

I'll check back later on the results of Spinosad, but on first observation today, it seems to be working!


    Bookmark   July 10, 2009 at 11:36AM
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Yes, here in my garden, I've seen them swarm a plant and reduce it to nothing but bare stems in one day. It's maddening since they are so fast to drop into the mulch and/or weeds, when one is trying to catch them.

I did hear someone say that one can dust the plants with self-rising flour, and that they eat it and die. I have not tried that. Spinosad, eh. Will have to look into it for the future. This has been my most pest free garden year to date. Hardly anything here except beneficials.


    Bookmark   July 10, 2009 at 5:53PM
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Okiedawn OK Zone 7


I use spinosad in a couple of different formulations. Spinosad is one of two ingredients (the other being iron phosphate) in Sluggo Plus, which I use for sowbugs and pillbugs. Spinosad is the active ingredient in the organic fire ant killer I use in the veggie garden, and it is the active ingredient in "Come And Get It" which we use once every 2 or 3 years for fire ant control in the yard around the house. It was originally marketed by Monterey as a fungicide and it worked great for me as a fungicide the first year I used it, but wasn't so great after that, so probably that first year was a low-fungus year anyway.

I haven't used any of the liquid sprays with Spinosad,
only the granular ones, but they have worked really well.

One thing I really like about Spinosad is that it doesn't harm the beneficials.

I did have blister beetles hit our Sweet Autumn clematis one year, about 4 or 5 years ago, and they did defoliate it pretty quickly.

Barbara, I'm glad the spinosad is working. Just think if that one scientist hadn't brought it back from the abandoned ruins of the rum distillery, then we likely wouldn't have it now since it never has been found any other place in nature.


    Bookmark   July 10, 2009 at 6:08PM
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Blister beetles are here too. They took out the last of the potatoes in two days. We killed as many as we could find, knocking them off the plants and stomping them. They love Sweet Autumn Clematis and hostas as well as potatoes and tomatoes. I too have many times squished them with my bare fingers but have also been blistered by them.

    Bookmark   July 10, 2009 at 10:21PM
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Yea, the little black devils like tomatos laced with Spinosad too, and it was their last meal around here. Heh heh. My tomato plants are still standing and vigorous enough to recover from what little damage the Blister Bugs did to them. I'm glad I caught it early enough to prevent a real plague.
In years past I probably would have wrung my hands and said, "oh dear" and then coated the entire garden with Sevin until it looked like a giant biscuit.
It was simply an accident that I happened onto the Spinosad. I'd been looking for SemiSpore to control the outbreak of hoppers I'd been going crazy over, but couldn't find any locally, and had to settle for the Spinosad because it was the only organically based product I could find. Actually, it's working for a lot of things, including the flea beetles lacing my eggplants. So, it was a happy find, and maybe it's a sleeper and will become more well known as time goes by.
Yes, Dawn, that was an amazing story about this being found only in that one abandoned Rum distillery. One good thing that happened as a result of "demon rum" I suppose.


    Bookmark   July 11, 2009 at 10:34AM
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I have them on my tomato plants and my eggplants too. They are eating just the foliage and doing it very quickly! I did a search on google to figure out what they were and I ended up here. Thank you for helping me figure out what they are. I have been hand picking them off for four days and the next day they are back. I haven't sprayed anything on them yet but it may be time to try some Spinosad. Can you find it at Lowes, Home Depot or TLC?

    Bookmark   July 18, 2009 at 10:58PM
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Okiedawn OK Zone 7

I buy it in Texas at a nursery that has a nice selection of organic products, so hopefully Barbara can tell you where she found it in Oklahoma.

Both Monterey and Green Light brands have a liquid organic insecticide that has spinosad as the active ingredient. It also can be found in pelleted form in some fire ant killers and snail/slug/pillbug/sow bug killers. Finally, there is one other formulation of liquid spinosad that I've seen, but I've only seen it in gardening catalogs and not in local stores and it was called Captain Jack's Dead Bug Brew, I believe, which is a reference to the fact that the microorganism was discovered in an abandoned rum distillery.

I've linked a photo of one product to give you an idea of what to look for.

It also can be found in some other agricultural products like Conserve or Entrust that you're more likely to find at a farm supply, tractor supply or feed-n-seed type store.


Here is a link that might be useful: One Example of a Spinosad Spray

    Bookmark   July 18, 2009 at 11:19PM
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I hate to say this but I've never had problems with them but it could start today. I looked in all the stores in a local town yesterday for liquid BT and did see Spinosad but believe it was for ants so assume it was the pelleted form. Will have to do some looking. Overall the Garlic Barrier has kept insect number down in my garden when I've kept it applied. Only found a few it doesn't work on. Hornworms are one. A good thread and will be on the watch in the future for these. Have seen the bugs around here just not on my tomatoes in huge numbers. Jay

    Bookmark   July 19, 2009 at 8:57AM
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Okiedawn OK Zone 7


I've only had them attack Sweet Autumn Clematis and that was only once, but they stripped it that year.

I suspect maybe they like more moisture and humidity than you and I normally have at our places, because people in central OK thru northeastern OK seem to have them in large numbers. When I see the blister beetles, I see one or two, but not great hoards of them. I've seen them around tomato plants, but not on them.

Until Barbara mentioned them in the first post on this thread, I didn't know they bothered tomato plants. Last year someone did have trouble with them on potato plants.


    Bookmark   July 19, 2009 at 9:40AM
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I found the Spinosad at Atwoods, under the label of Nature Guard. It really knocked out the Blister Beetles in a hurry. I suspect they were imported by by DS inadvertently. He'd bought a pickup at a fantastic deal from a guy, who couldn't use it anymore due to health, ...on the condition that DS haul off a bale of straw, which then ended up in a pathway close to the tomato plants in question. I've suspected the BB eggs hatched out of that bale, and then onto my tomatos.
Anyways, there is now no evidence of damage.
I am sold on this product and have been using it for a lot of leaf eating bugs, such as flea bettles. I don't know if it will work on grasshoppers, but we'll find out because some have started nibbling various things in the borders, and in a small corn plot.
I do think it knocked out the nymphs that were eating my grape hyacinth vines, because they have stopped showing evidence of damage, and I just don't see them hanging out there anymore. This was way before I applied the SemaSpore, which I had to order online.


    Bookmark   July 19, 2009 at 10:17AM
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I just had a coworker last week mention that he had them attack his squash. Of course he is like most and uses Sevin for everything. Guess it worked. But as I said I've been lucky and have only seen one I believe so far. Maybe they don't like the Garlic. Jay

    Bookmark   July 19, 2009 at 10:25AM
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devilwoman(7a Warr Acres OK)

Felton, depending on where in the state you are, Horn Seed in NW Okc had it when I was in there Friday afternoon. They are also having a 40% off sale on everything in the store this weekend.


    Bookmark   July 19, 2009 at 10:33AM
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    Bookmark   July 19, 2009 at 8:05PM
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I've had them attack hot pepper also, ate leaves and fruit, nothing but a stem when they got done. they will strip alot of plants if allowed.

    Bookmark   July 20, 2009 at 11:42PM
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Okiedawn OK Zone 7

Well, I found three in the garden yesterday while harvesting tomatoes (never had them on tomatoes before) and snipped them in half with my garden scissors. I did pick up some spinosad spray today so I'm ready for them if they appear in large numbers.

Every time I say "I haven't seen those here", they show up within a few days, so I am going to stop saying that!

    Bookmark   July 21, 2009 at 5:41PM
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Dawn as you and I both know the quickest way to bring a plague is too state you've never had a problem with something. Hopefully you are ready and they won't be too bad. Jay

    Bookmark   July 21, 2009 at 7:11PM
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Okiedawn OK Zone 7


I also did something highly out of character yesterday--I killed three tomato hornworms. Snipped them right in half with my trusty garden scissors. Normally, as you know, I'd let them live and move them to a datura or something. However, I wasn't in the mood to put up with them yesterday and they were on my SunGold and Black Cherry tomato plants. All smart hornworms know you don't mess with my favorite plants. So, that's three less hummingbird moths we'll have to enjoy, but I don't care. They were just in the wrong place (in my garden on my favorite plants) at the wrong time (the same time as me)and I am still recovering from the flu and cranky, so...snip, snip went the scissors and bye, bye went the worms.

I'm ready for any other blister beetles that show up! I've got a bottle of Spinosad spray concentrate so all I have to do is mix up a bit and put it into the sprayer. I've got my trusty scissors. I've got a "no blister beetles allowed" attitude.

And, I hesitate to mention the next thing here in an insect thread, so am going to put it on a new thread. It involves purple tomato leaves and it is a disease that is new to me.


    Bookmark   July 21, 2009 at 7:30PM
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Whoa guess everybody and everything better tip toe around Dawn's place for a few days!!! LOL. Odd you mentioned the hornworms. A lady at work who had 12 heirloom/op plants asked me yesterday about the hornworm problem. I'm afraid she is too late to do anything. She had always picked them off as she don't like spraying. I told her I was now up to 45 and thought they may of ruined another plant. As it was a late and small one and not enough time to recover and set fruit. She said how many she had pulled and it was over 60 off 12 plants. Said they have devastated them. I told her it might be too late now too spray. Being they are basically without leaves as she said. Like I told her they are worse than I've ever saw them and that includes last year when the drought was even worse. In fact she is where it has rained some. Like I said everyone around here has had terrible problems with them. And I've never seen them go on for a month like this year. She said the same thing. But another coworker 35 miles north of me and about 15 miles NE of her claims he hasn't had a one. He moved here from north central KS and claims he don't know what they are. He did have the bad hail and maybe that destroyed them I'm not sure. Jay

    Bookmark   July 22, 2009 at 7:14AM
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Okiedawn OK Zone 7


Well, until this week I would have said all "my" hornworms were hanging out in SW Kansas, but then a few more showed up here, so we know that is not true.

When we have a bad hornworm year here, I usually start seeing them in March or April and I am not as kind to the very early ones because you know they could strip my seedlings bare before they can grow. I try to catch them very small in the earliest spring and feed them to the chickens. Once the hornworms are 4" long or so, the chickens won't touch them either.

And, you're right, no one had better get in my way for the rest of the week. I am so far behind on garden work, and on putting up produce, that I am not putting up with any nonsense from anyone. LOL

The break in the weather is rejuvenating both the garden and me. I worked in the garden for 4 hours this morning because the cool temperatures were too lovely to pass up. I didn't see any hornworms or blister beetles today, and only one stinkbug, so that added to my good mood. This afternoon, I'll be trying to work my way through a huge mound of tomatoes and peppers. I'm going to can most of the peppers, and maybe make some jalapeno jelly, and then roast some big tomatoes and boil them down to make sauce, and dehydrate a few hundred smaller ones. If I finish all that today, then tomorrow I'll get the onions into the cellar for long-term storage, dig potatoes, pick several dozen sweet peppers and put them up, and pick black-eyed peas. The melons are coming in at the rate of one or two a day, but we eat them about as fast as I pick them.

Your ongoing drought seems like it has really contributed to the insect problem this year. I know we always have more pests in drought years, and they are just relentless.

Your coworker who hasn't had a single hornworm will have some soon enough. I don't think I've ever had a year with absolutely none. His turn will come. (Not that I am wishing them upon him or anything!)


    Bookmark   July 22, 2009 at 12:55PM
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We were suddenly attacked by these bugs. They were eating the tomatoes and hostas. We had great success spraying the plants with a dish soap/water mixture. In three days the tomatoes were clear of them and only a few stragglers on the hostas!

    Bookmark   August 1, 2009 at 10:47AM
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I had these blister beetles attack my tomato plants and seemed to triple in number overnight. Read about the soapy water treatment this morning and it seems to have solved the problem. I sprayed the beetles right off the plants. I saw a couple of them a few hours later and they seemed disoriented.

Thanks for sharing. My tomatoes thank you too. These bugs are far worse than horn worms and they really multiply fast. I saw a few of them a couple of days back and ignored them. I would say if you see a few, get right on top of them. They really multiply fast.

    Bookmark   July 19, 2011 at 12:08PM
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