In this article, we look at the blister beetle, why it is so dangerous, and whether it can fly or not. To answer clearly upfront- yes, they can fly!
Blister beetles are brightly colored toxic little beetles often found in alfalfa fields.
They are toxic and called blister beetles because they secrete a liquid when threatened or injured called cantharidin.
The toxin can cause irritation and blistering if it directly touches human skin.
It can also cause serious health issues in animals and be fatal.
Blister beetles have wings to move from flower to flower or plant to plant. So they can fly, but they are slow fliers.
What Are Blister Beetles?
Blister beetles are insects that belong to the family Meloidae. They are sometimes called acid flies or even Spanish flies.
Blister beetles are considered aggressive in nature because they secrete a toxin called cantharidin when disturbed.
If cantharidin comes in direct contact with human skin, it can cause irritation and blistering.
Furthermore, if ingested in large amounts, it can cause irritation to the gastrointestinal and urinary tract.
Blister beetle poisoning can be fatal to animals, especially horses that feed on alfalfa hay, where these bugs are often found.
There are about 4000 species of blister beetles across the world, out of which nearly 410 species are found in the United States.
How To Identify Blister Beetles?
Blister beetles have small bodies that appear leathery in texture.
These beetles appear long and cylindrical in shape but, in reality, have small torsos.
The cylindrical illusion results from the wings that curve around their abdomen.
They have a wide head, long legs, and beaded antennae.
Another distinct characteristic of blister beetles is their varied color palate.
They can be found in dull colors like ash brown, black, and gray or in bright colors like green and yellow.
For example, the Lytta and Pyrota species are brightly colored in hues of green and yellow.
The bright colors often serve as a warning to predators to stay away.
Yet other species of blister beetles belonging to the same genus Epicauta are starkly black in color.
The black blister beetles and striped blister beetles are the most commonly found species in the North American states.
Can Blister Beetles Fly?
Since they are plant pests and also dangerous to livestock, it is important to know whether they can fly or not.
If they can, how well do they fly, and how dangerous is it?
Well, blister beetles do have wings, and they can fly. But thankfully, they are not big fliers.
Do They Have Wings?
Yes, they do have wings, as mentioned above.
The wings of adult beetles cover their abdomens completely.
The curved wings create an illusion of the beetle being slender and cylindrical when their torsos are far smaller.
Unlike other insects, their wing covers do not meet in the middle.
Blister beetles can fly but are slow fliers, given their heavier body weight.
As discussed earlier, various species are colored differently when it comes to blister beetles.
Some species have striped wings and solid-colored bodies, making them appear dangerous to predators.
Which Species of Blister Beetles Can Fly?
All species of blister beetles have wings and can fly.
As discussed above, blister beetles have wings covering their relatively short bodies.
They are not fast fliers because the wings cannot fully sustain their heavier body weight.
But they use their wings to fly toward lights during the evenings.
Where Can I Find Blister Beetles?
You can find blister beetles in several places.
Region-wise, several species of blister beetles are found in North America in states likeWisconsin, Florida, Minnesota, etc.
Other species exist in The West Indies, Central America, and South America.
As for their habitats, blister beetles are found in alfalfa hay fields, as adult beetles often feed on alfalfa flowers.
They also infest plants of garden vegetables such as tomatoes, potatoes, lima beans, etc.
The larvae of blister beetles feed on grasshopper eggs and nesting bee eggs.
So you will also find a large number of blister beetles in areas where there is a higher number of grasshoppers.
Do Blister Beetles Bite?
Blister beetles do not bite. They have no stinger to bite or sting.
But having said that, blister beetles are considered toxic because their bodies carry a blistering agent called cantharidin.
When threatened, injured, or crushed, these insects secrete an odorless liquid that can irritate human skin and cause blisters on direct contact.
If ingested, cantharidin can irritate the gastrointestinal and urinary tract.
In animals, especially horses, ingesting cantharidin can cause poisoning and death.
Hence the beetles’ presence in alfalfa hay is often concerning for horse owners as horses feed on alfalfa hay.
While these bugs do not actively harm humans or animals, their toxins can cause harm.
Dead beetles might get crushed and mixed into the hay, and if ingested, the horses could die.
Frequently Asked Questions
How can you identify a blister beetle?
Blister beetles are a unique type of beetle that is easily identifiable due to their slippery, oval shape and black or brown stripes running the length of the body.
They range in size from very small to over 1 inch in length and have six legs and an elongated head.
Blister beetles produce a toxic substance called cantharidin that is released when their bodies are touched, hence their name, blister beetle.
To identify a blister beetle, look for its oblong shape and striped coloration.
What happens if you touch a blister beetle?
Touching a blister beetle can have several adverse effects.
These beetles secrete an oily, caustic substance from their leg joints that contain cantharidin.
If this substance is rubbed onto the skin, it can cause an intense burning sensation and a rash of fluid-filled blisters that can make your skin swollen and itchy for several days.
In addition, if these blisters are ingested or come into contact with mucous membranes like your eyes, they can cause inflammation.
It could even cause more serious symptoms such as nausea, vomiting, renal dysfunction, and sometimes diarrhea.
Can you pop a blister beetle bite?
Blister beetle bites should not be popped, as this can cause infection.
The best way to treat a blister beetle bite is to use an over-the-counter antihistamine, such as Benadryl or Zyrtec.
This will help reduce the swelling and itching and also reduce the risk of infection.
If the bite does not improve with these medications, you may need to seek medical attention.
Blister beetle bites are often misdiagnosed as wasps or bee stings; it is important to properly identify the bug before attempting self-treatment.
How do you get rid of blister beetles?
The best way to get rid of blister beetles is by controlling the population at its source.
This can involve changes in land management practices, such as eliminating weeds and mowing or increasing the rotation of crops on infested fields.
Chemical control may also be necessary, such as treating larvae with insecticides or spraying with pyrethroids.
Biological control options are an environmentally friendly alternative if they are used correctly.
Certain parasitoid wasps will feed on blister beetle larvae, reducing their numbers effectively.
Yes, blister beetles do fly. They do not fly at a very fast speed because their wings cannot sustain their heavier body weight.
But they do use wings to move between flowers and plants.
It has also been observed that blister beetles often fly toward the light during nighttime.
Thank you for reading.
The fact that blister beetles are so dangerous often causes concern among those that find them in their gardens or yards.
And to see them flying can cause even more concern! Read on as several of our readers have inquired about their flight capabilities over the years.
Letter 1 – Blister Beetle
Arizona Beetle on Creosote Bush The attached picture was taken in an area called Cascabel in Cochise County, Arizona. The area is approximately 30 miles north of the town of Benson, at an elevation of 3500 feet above sea level. The bugs were quite numerous on several creosote bushes. Please identify. Thanks, Bob Evans Beetle on Creosote Bush, Cascabel, Arizona Hi Bob, Your beetle is a Blister Beetle in the family Meloidae. It closely resembles an unidentified beetle in the genus Pyrota from Texas that was posted to BugGuide, but it is not an exact match. We will contact Eric Eaton for assistance. Update: (07/28/2008) From Eric Eaton Daniel: Hope your lecture at the Getty went well! … Your identifications of the blister beetles are correct to genus. There is no easy way to determine species without having a collection to compare to, or the specimen in hand to run through a “key.” Lots of individual variation in color (and pattern in the case of Pyrota) makes ID impossible from an image alone. … I think that covers all your questions. Keep up the great work. Eric
Letter 2 – Blister Beetle
is this some kind of Blister Beetle? Hi, just found your web site – awesome bugs. I am in Moose Jaw, Saskatchewan and found this beautiful bug on a poppy leaf this afternoon. The only thing that I can find that sort of resembles it is the blister beetle, however it has a dull plain back and only the head parts and some of the under belly are iridescent. Can you ID? Thanks D Hi D, Your are correct. This is a Blister Beetle. We believe it is in the genus Lytta. We found a match on BugGuide, also from Canada, but it is not identified to the species level. We will contact Eric Eaton to see if he can comment. Update: (07/28/2008) From Eric Eaton Daniel: Hope your lecture at the Getty went well! … Your identifications of the blister beetles are correct to genus. There is no easy way to determine species without having a collection to compare to, or the specimen in hand to run through a “key.” Lots of individual variation in color (and pattern in the case of Pyrota) makes ID impossible from an image alone. … I think that covers all your questions. Keep up the great work. Eric
Letter 3 – Blister Beetle
Do you know what kind of insect this guy is? He’s quite happily chowing down on my bell pepper plant, and he seems to be alone at present. Just saw him for the first time today. I have NO idea what he could be, so no clear idea of what direction to research in. This photo is high resolution so you can size it as you need to for easy viewing. 🙂
We couldn’t identify your exact species of Blister Beetle, so we wrote to Eric Eaton. Here is his answer: “Spectacular! I’d love to see that one IN bugguide…. It is a species of Epicauta. Nobody could tell you more than that because there is a whole COMPLEX of species that all look like this one! Pretty sure they are parasites of grasshopper egg pods in the larval stage. Eric”
Letter 4 – Blister Beetle
i found this bug in my window well on the side of my house. it is about 2″ long and maybe 3/8″ wide. the bug is a lot brighter and more irredescent than what the pictures show, but hopefully you will be able to identify it. also does it fly? when i saw it it just kept crawling everywhere but are there wings under the shell on its back? thanx
edmonton, alberta canada
This is the second photo we’ve gotten this week of a Blister Beetle, Lytta cyanipennis. This beetle can be very abundant locally, appearing for only short periods of time. Be careful though, handling a Blister Beetle can cause an irritating reaction in sensitive people, hence the common name.
Letter 5 – Blister Beetle
Unknown bug in Southern Arizona
We found this trying to enter our home during monsoon season but have never seen it before. Can you identify it? Picture attached. Thanks,
We wrote to Eric Eaton who lives in Arizona to see if he knew your beetle. Here is his response: “We have just a FEW beeles here:-) Thank God this is one I DO know! It is a blister beetle, Pyrota akhurstiana (better check the spelling on the species name, tho). They are reasonably common at lights at night. Eric” We double checked Eric’s spelling which is on the money.
Letter 6 – Blister Beetle
Hello – please apply your expertise to identify this gorgeous beetle I saw on the ground in New Mexico (Chaco Culture N.P. to be exact) in September. I have searched on the web with no success, but your excellent website has given me hope. He was quite large…an inch? I”m trying not to exaggerate and turn my beetle into a shaggy dog! I know you only select at random, but I’m crossing my fingers that you will help. Thanks in any case for a great site.
Barbara in Ontario.
This is a Blister Beetle in the genus Megetra, possibly Megetra vittata. They are sometimes known as Oil Beetles. Here is a page on BugGuide with some interesting information.
Letter 7 – Blister Beetle: Epicauta longicollis
Subject: tiger beetle? Location: near Holbrook, AZ October 5, 2013 4:46 pm Howdy! Long time watcher, first time asker. I was taking a road trip this summer with a friend of mine, and we stopped by the Petrified Forest National Park in Arizona along the way. Lotsa cool things to see there, but one thing that astounded me were these funny beetles. There were hundreds of them, and they were hanging out on some sage brush. They were bright green, very nearly matching the color of the leaves. The strange thing was — as many beetles as there were — they tended to be gregarious, hanging out in large numbers on one bush, but none on a bush just inches away. We saw the same thing — lotsa beetles on a single bushes — in several places in the park. This was in mid-July. Any ideas what this might be? I poked around a bit, and the best I could come up with was some sort of tiger beetle. cheers, Signature: Jim Hi Jim, Your photos are quite excellent in quality. We hope you will consider sending us quality images of interesting creatures again in the future. Tiger Beetles are solitary predators that move very quickly. This is actually a Blister Beetle in the family Meloidae. We believe we have correctly identified it as Epicauta longicollis, a species represented on BugGuide by a single photograph that was taken in Dewey , Yavapai County, Arizona this past July. We originally found Epicauta longicollis pictured on the Yavapai County Arizona Cooperative Extension page of the University of Arizona College of Agriculture and Life Sciences website. We have learned that Holbrook is in Navajo County. We are uncertain of the range of Epicauta longicollis. Cool beans. Thanks so much! I probably wouldn’t have gotten so close if I had known earlier that it was a blister beetle. 🙂 cheers, Jim
Letter 8 – Blister Beetle
Subject: beetle Location: Pasadena MD April 13, 2015 2:33 am I found a species of beetle hiking across the kitchen counter and cannot identify. I walked it onto a paper towel and released outside but it did not seems to have the ability to fly. Signature: Brian S Dear Brian, We believe your Blister Beetle is Lytta aenea, a species with no common name, based on this image posted to BugGuide.
Letter 9 – Blister Beetle
Subject: Beetle ID Location: Hurricane Rd pass, Temblor Range, east of Carrizo Plains, CA March 29, 2016 7:46 pm I found this beetle on March 26, 2016 at the top of Hurricane Rd pass in the Temblor Range just East of Carrizo Plains National Monument. It is large – see my fingers for scale. It was the only one of its kind I saw that day and we walked the roadside for over 1.5 miles. The elytra are short and do not come close to covering it’s abdomen, as you can see in the second picture. It did not fly, but fell off my fingers and into the grass. It was found in Bromus grass and Amsinkia. Temperature was about 65 degrees F with a strong wind, ample sunshine. Signature: Judy Neuhauser Dear Judy, This is a Blister Beetle in the genus Lytta, and we wish you included a view of the beetle’s head because it does not look like the Master Blister Beetle, Lytta magister, a species that is active in Southern California at this time of year, as evidenced by the image we just posted, however the Master Blister Beetle has an orange head and thorax and your individual appears to have a black head. Also classified in the L. magister group according to BugGuide is Lytta funerea, which is represented by a single posting of a male of the species on BugGuide with three images. That individual has a black head and orange markings on the abdomen like your individual, and females, which we suspect you encountered, are often bigger with bigger abdomens. We would urge you to exercise caution when handling Blister Beetles because according to BugGuide: “Pressing, rubbing, or squashing blister beetles may cause them to exude hemolymph which contains the blistering compound cantharidin. Ingestion of blister beetles can be fatal. Eating blister beetles with hay may kill livestock. Cantharidin is commercially known as Spanish Fly” and is sold as an aphrodesiac.
Letter 10 – Blister Beetle
Subject: Please identify? Location: Haywood County, NC April 14, 2016 6:18 am We have had an ‘outbreak’ of these beetles by our garage door. There are hundreds of them. We had mulch blown in a couple of weeks ago and are trying to determine if they came in that way or if this is just your every day beetle apocalypse. Signature: Buggy in NC Dear Buggy in NC, This is a Blister Beetle in the family Meloidae, a group with a complicated life cycle. Larvae are generally predatory and very particular about their hosts, and depending upon the species of Blister Beetle, they generally parasitize solitary bees or grasshoppers. We have identified your Blister Beetle as Lytta aenea, based on this BugGuide image. When conditions are right, there can be large population explosions of adult Blister Beetles that feed on vegetation. According to BugGuide: “recorded larval hosts: Colletes thoracicus (Colletidae) adults recorded feeding on Amelanchier, Carya, Crataegus, Fagaceae, Malus, Pirophorum, Prunus, and Salicaceae.” Blister Beetles should only be handled with caution as they are able to exude a compound, cantharidin, that can cause blistering and irritation in human skin.
Letter 11 – Blister Beetle: Lytta aenea
Subject: unidentified beetle Location: Alexandria, Virginia April 19, 2016 6:54 pm I got several good photos of this attractive beetle today at Huntley Meadows in Alexandria, Virginia. I cannot find it in my reference book, so I was hoping you can help me out. Thanks! Signature: Seth Dear Seth, Your Blister Beetle is Lytta aenea, and because insects have evolved and adapted to maximize their ability to reproduce, many species make yearly appearances when they emerge as adults at the same time across a wide area. A few days ago, we posted our first image this year of Lytta aenea.
Letter 12 – Blister Beetle we believe
Subject: Larger than a Boxelder Location: Mound, MN May 25, 2016 7:00 am Dear Bugman, This largeish black bug, with orange and black legs, and a hard black shell, with silvery fur on his belly was trapped between my screen and door last night. I’ve never seen one before. We live in Minnesota and have a garden and 3 dogs. Wondering what it is, and if it’s toxic to pets if eaten by curious and non-discriminating terriers. Thank you. Signature: Melanie Bisson Dear Melanie, It is difficult for us to be certain because of the odd camera angle, but we believe this is a Blister Beetle in the family Meloidae, possibly Lytta aenea, which is pictured on BugGuide. Many species of Blister Beetles are able to secrete a compound known as cantharidin that may cause blistering in humans. We have read reports of livestock being poisoned by ingesting Blister Beetles with hay. According to Pet MD: “Blister beetles are a type of insect found primarily in the southwest and Midwest regions of the United States. These beetles harbor a very powerful toxin called cantharidin, but, unlike other types of insects, it does not spread this toxin through biting. Adult blister beetles feed on alfalfa flowers and crops, the same crops used for horse and cattle feed, and when the crops are harvested the beetles are often killed in the process, contaminating the crops with their body parts and fluids and causing illness in the horses that eat the contaminated feed. Blister beetles are extremely toxic when ingested by horses: as few as five to ten beetles may be fatal to a horse. The cantharidin toxin affects many bodily systems. It is extremely irritating to the digestive tract and causes blisters and erosions from the lips and tongue all the way through to the lining of the intestines, which causes abdominal pain (colic) and diarrhea. This toxin also causes damage to the kidneys and the heart.”
Letter 13 – Blister Beetle
Subject: Grey beetle with spots Geographic location of the bug: Mountain home idaho Date: 09/03/2017 Time: 07:53 PM EDT What is this found it crawling out in the grass next to my kids How you want your letter signed: Shay Stewart Dear Shay, We are confident we have correctly identified your Spotted Blister Beetle, Epicauta maculata, thanks to this BugGuide image. Though BugGuide does not report any sightings from Idaho, there are sightings from nearby Montana and Wyoming. Blister Beetles should be handled with extreme caution, or even better, not handled, because contact with the cantharidin that many species secrete can cause blistering in human skin.
Letter 14 – Blister Beetle
Subject: Small black beetles with jewel colors of blue and violet Geographic location of the bug: Little Belt mountains Montana Date: 08/20/2018 Time: 11:48 AM EDT Your letter to the bugman: I have seen these in the months of June and July on blooming mountain lupines in the Little Belt and the Castle Mountains. I would like to know what kind of beetle these are? How you want your letter signed: David C Powers Dear David, The image of a solitary beetle on a blossom is definitely a Blister Beetle in the family Meloidae, but we are uncertain of the species. The other image showing an aggregation of Beetles appears to be a different species. Can you clarify any information on these two images, especially the group of beetles. Were they found aggregating as the image depicts? Here is a BugGuide image of Linsleya sphaericollis that resembles the Blister Beetle in your image of a solitary individual, but again, we cannot verify the species.
Letter 15 – Blister Beetle
Subject: Black beetle, red wings Geographic location of the bug: Guilford, CT Date: 04/22/2019 Time: 08:58 AM EDT Your letter to the bugman: Could you tell me what this bug is? There are a number of them in our front (southern exposure) garden. I can’t find a good match online. How you want your letter signed: Abigail W. Dear Abigail, Generally, when we receive an identification request, we have at least an idea to what family a creature belongs, which makes research easier, but in the case of this Beetle, we were not even sure of a family. We turned to Arthur V. Evans excellent book Beetles of Eastern North America and we eventually identified your colorful beetle as a Blister Beetle in the family Meloidae, Tricrania sanguinipennis, but it is very atypical looking for a Blister Beetle. We located an image on BugGuide for comparison. According to BugGuide, it is “A parasitoid of colonial bees, such as Colletes.” Thank you so much for replying! I’m glad to have provided a challenge. After contacting you, I remembered about our local agricultural station. They were also able to ID my beetle as the Tricrania. I’m guessing they are thoroughly enjoying my ground bees…. Abigail Wasserman.
Letter 16 – Blister Beetle
Subject: What is this Geographic location of the bug: Carlsbad, NM Date: 05/26/2019 Time: 11:30 PM EDT Your letter to the bugman: It flew away shortly after the photo. How you want your letter signed: Brent Griffith Dear Brent, This is a Blister Beetle in the genus Pyrata, but it does not appear to be the similar looking Charlie Brown Blister Beetle. According to BugGuide: “27 spp. in our area.”
Letter 17 – Blister Beetle
Subject: Swarm of Green Beetles Geographic location of the bug: Warren, ME Date: 07/08/2019 Time: 05:44 PM EDT Your letter to the bugman: This swarm of green beetles just showed up today, filling our Hawthorne tree and falling all over our deck. My dog ate one and now I’m terrified they are poisonous. They look a bit like Emerald Ash Borer pics that I’ve seen. We run a large 163 acre organic farm, so if this thing is going to attack crops, I’d like to know and try to prevent damage. Right now it only seems to care about the Hawthorne blossoms… How you want your letter signed: Farm Dog in Maine Dear Farm Dog in Maine, This is a Blister Beetle in the family Meloidae, and based on BugGuide images, we are confident it is Lytta sayi. According to BugGuide: “beetles feed largely on various flowers; larvae have been reared from cells of Agapostemon virescens.” Blister Beetles are fascinating insects with complex life cycles. The larvae of most species feed on either Grasshoppers or Solitary Bees. Many Blister Beetles are able to secrete a compound known as cantharidin that is known to cause blistering in human skin and there are reports of horses sickening and even dying from accidentally ingesting Blister Beetles while eating hay. Of the family, BugGuide notes: “Pressing, rubbing, or squashing blister beetles may cause them to exude hemolymph which contains the blistering compound cantharidin. Ingestion of blister beetles can be fatal. Eating blister beetles with hay may kill livestock. Cantharidin is commercially known as Spanish Fly.”
Letter 18 – Blister Beetle
Subject: Identify this bug? Geographic location of the bug: Columbus, N.M. Date: 11/08/2019 Time: 10:00 AM EDT Your letter to the bugman: We are on the border of New Mexico and saw this bug about the approx size of a quarter. How you want your letter signed: Gaila Dear Gaila, This is a Blister Beetle in the genus Megetra and we identified it on BugGuide. There are three species in the genus, and two are found in New Mexico, but they look so similar, we cannot discern a difference.
Letter 19 – Blister Beetle
Subject: Texas beetle Geographic location of the bug: Big Bend N.P. Date: 04/14/2021 Time: 05:36 PM EDT Your letter to the bugman: Can you identify these beetles found feeding on Lupine? How you want your letter signed: H2oggre Dear H2oggre, Thanks for sending multiple camera angles of your Blister Beetle in the family Meloidae. We believe based on this BugGuide image that it is Lytta cribrata, but we would not rule out a different species in the genus. It is described on BugGuide as: “Pronotoum black at center, broadly orange at sides; head with a diamond-shaped orange frontal spot” and its range is listed as: “sw. TX (Chinati Mts and Eagle Pass), Mexico (Chihuahua, Durango).” Does that match your location in Texas? Thank you Daniel. Yes it does match Chihuahuan desert area. I need to look up what the “Pronotoum” is, though. If is the center “thorax section” [before the black section with its wings; yet behind the red and black section with its eyes and antennae] that fits the description. It certainly matched the color markings if that is what I think the pronotoum is. The lobed antennae seemed to me rather distinctive as does the y-shaped pincer tipped legs. Any mention of those in the description of Lytta cribrate? Plus the wings are very textured. That is not dew on the surface. I really appreciate your help Daniel. Richard Todd Good morning Richard. The Pronotum is defined on BugGuide as: ” the upper surface of the prothorax, the first segment of the thorax. Shape of the pronotum is often important in identification of beetles, and many other groups.” While Coleopterists, entomologists who specialize in Beetles, have an extensive vocabulary of terms they use to describe characteristics, we believe punctate, which is defined on BugGuide as “marked by spots, dots, points, depressions, or punctures” could be used to describe the texture of the elytra or wing covers on the Blister Beetles you observed.