Wednesday, October 14, 2009

Blister Beetles


Blister Beetles in the Family Meloidae are found throughout most of the United States. There are many different species, but each one has an elongated body with a very narrow thorax. This cylindrical shape is very typical of blister beetles. They are commonly found in  vegetable and flower gardens. Look for them near croplands, especially forage crops. The adults feed on a wide variety of foods like clover, alfalfa, soybean, radish, carrot, beans, cabbage. In the wild they will feed on pigweed. They also will feed on ornamental plants like Hostas. The black variety is especially fond of goldenrod. After mating, the females will lay eggs in clusters in the soil. After the larvae hatches it will seek out grasshopper eggs and young grasshopper nymphs that are beginning to surface from underground. Sometimes they will also feed on bee larva. This makes them an important natural control measure for these often time invasive insects. Blister Beetles aren't always the "good guy" however. They have a dark side. Blister beetles contain a chemical in their legs called cantharidin. This chemical is extremely toxic, especially to horses. The horses come in contact with the beetles in their feed. The beetles feed on alfalfa, then the horses also feed on the alfalfa. As few as 550 beetles can kill a young horse weighing 275 pounds. This chemical is also found in the controversial drug called "date rape drug".  


I myself have had a run-in with these beetles. A couple of summers ago we had 100's of these beetles all over our farm. They were in the gardens, in the flowers beds. They were feeding in large numbers on my hostas, and had nearly defoliated the hostas before the summer was over. At night they were around the pole lights. I also spent a lot of time near the pole lights, looking for bugs to photograph, or capture for my collection. One night I felt one of these beetles land on my neck, as I went to brush it off me it released some of this awful chemical and blistered my skin. This blister hurt for days and left a welt for over a week. These beetles mean business, this is chemical warfare at its finest.



These beetles are best looked at and not touched. They are common and easily found, some years there seems to be more of them, than other years. In the past two years I've not seen populations of them anywhere near like what I had two summers ago.

Pictures:
1.) Ash-Gray Blister Beetle
2.) Black Blister Beetle
3.) Striped Blister Beetle (picture by: Steve Scott) This is the variety that blistered me, and from what I've read this species contains higher concentrations of cantharidin than the other two species pictured here.



18 comments:

  1. Thanks so much for clarifying the grasshopper/blister beetle relationship. I'd heard there was a connection, but didn't know exactly what it was.

    Our experience over the past 20+ years in Arkansas has been similar to your. Blister beetles can be a real problem in the vegetable garden some years and other years there will be just a few around. They are especially bad about defoliating tomato plants when their population is high. Since we garden organically, we pick off and drown the blister beetles in bad years and have never suffered any reaction. Of course, we are careful not to crush them.

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  2. You are very welcome, these beetles are very interesting, equally destructive and beneficial. This year the numbers of these were way down, makes me wonder if it was because of all the rain. I'm sure saturated ground would be hard on the eggs and larvae. My incident with the blister beetle was unfortunate, but a definite learning experience. That hurt like crazy!

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  3. I took a photo of the black ones earlier this year. Never had an ID. THanks!

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  4. You're welcome Moe. I found several of the black ones this year, and they were all on goldenrod. I didn't see hardly any of the other two species. It seems they are an on again, off again species.

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  5. I'm trying to identify a beetle that I think is a blister beetle. I've been finding them in the house. Will they come in and actually live inside? Mine have the body of the blister beetle but have a red neck and legs. I found pictures of ones that look exactly like mine but the descriptions I've found all say they are native to Hawaii and the southern coast.

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  6. Did you happen to keep one? Or do u have a picture of the one in your house? It is not out of the question for an insect found in Hawaii to make it to the mainland.I would like to see a pic and I will try to help u ID it. If I can't figure it out, I have several friends that are bug experts and I am sure they will be happy to help.

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  7. Yes I did keep one. How can I send you a pic?

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  8. I'm so glad you kept one, I must admit I am extremely curious what your little bug looks like. You can email the image to me at
    MOpiggys@aol.com

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  9. I just sent you a photo!

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  10. I just looked at the image and I am pretty sure your beetle is a false bombardier beetle. From the image it is hard to tell if it is Galerita bicolor or galerita janus. They are beneficial at controlling insect populations. Both can emit a chemical defense that makes a loud "pop" sound when expelled.

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  11. All of a sudden, for the past few days, I have seen SEVERAL black bugs crawling across the carpet in my living room. I have looked at many pictures of different kinds of beetles and the bugs seem to resemble blister beetles. Why are they coming in to my house??? I have lived here for 10 years and I have never had this kind of problem before. What could be attracting them inside my home and how do I get rid of them?

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  12. Thank you for your information, I am glad I learned this before making a bug collection. Last year I just grabed them up and put them in a jar... I must have gotten lucky.

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  13. for the past several weeks, during a horrible heat wave and no rain, these monsters started in on my hostas. they are now on all sides of my house, as i have a large hosta collection with over 500 varieties. they are devastating them all. will sevin work as a control? i am heartsick over this i have never seen these awful things before. susan

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  14. i have a large hosta collection that is being destroyed by these. will sevin work to kill them?

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  15. These little beetles have a voracious appetite, and play havoc on my hostas a few years ago. I would say Sevin would work fine to repel them, certainly can't hurt to try.

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  16. I live in Middletown, CT and am finding these beetles in my grass in October. I have no garden and not many flowers. A neighbor does have ground bees and also has Blister Beetles a plenty near where her ground bees are, but to my knowledge I have no ground bees either. Not sure about the grasshopper population. Have see a few, but not many. I have so many questions that I am not able to get answered. I.E. Are these beetles nocturnal? Where do they go at night? Do they live undergrown? I hear a killing frost will kill them, but then also read, they live only a few weeks. Are both points true? I am scared because I have two pups that use the area I have seen these beetles in to potty outside. I am fearful they may eat of play with one and what the result might be. Therefore, I do not want to treat with chemicals and killing them, I realize that the chemical may live on anyway.

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  17. Has any one tried using Diatomaceous earth? I find it is great for many, many uses and effective for many different kinds of bugs. It is very fine, almost like cornstarch or talc. It works because even though it is very fine, it retains microscopic sharp edges...nothing to us, but deadly to bugs. It causes cuts in the ectoskelton shell of the bug, they dry out and die. Using a special duster that can apply the dust finely to your plants is the secret. It has a long nozzle and has an adjustable end so that you can apply the earth on the underside of leaves. It works for fleas, slugs, roaches, beetles and a lot of other bugs. It has to be reapplied after rain.

    It can be purchased at almost any farm store, I get mine at Tractor Supply in the poultry section. I use it mixed with sand and wood ashes, 1/3 of each in a large box as a dust bath for my chickens...they love it, and it works great. I have even mixed it into their food, it works for internal parasites also.

    I hope this helps.

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  18. I think this a false blister beetle. Will send a photo. Thanks!

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