Blister beetles can cause irritation on your skin and be deadly to your pets and other animals in your home. In this article, we discuss some ways to get rid of them.
Blister beetles are a common pest found in gardens and fields.
They are toxic pests because they release a blistering agent when injured or crushed, which can cause blisters if it comes in direct contact with the skin.
These pests are harmful to humans as well as to your plants and crops.
There are several ways to get rid of them, manually and using insecticides. I will discuss these in detail in the following article.
What Are Blister Beetles?
Blister beetles are part of the Meloidae family of insects.
They are called blister beetles because of a chemical called cantharidin that comes out of them and causes irritation and blisters on the skin when you touch them.
What Do They Look Like?
Blister beetles are usually between 3/4th to 1-1/4 inch in length.
There are many species of blister beetles, of which only a few are found in the US. Most have an elongated cylindrical body, a short thorax, and a wide head.
They are soft-bodied insects.
Blister beetles may also come in several colors, such as ash gray, brown, black, and green. You might also spot striped blister beetles or those with spots.
Where Are They Found?
Blister beetles are commonly found all across the US, South and Central America, and the West Indies.
Moreover, grasshoppers are the main prey for blister beetles. Hence you will find them wherever you find grasshoppers, which is gardens, parks, and other open areas.
What Damage Do They Cause?
Blister beetles can feed on crops and flowers and cause a lot of destruction. When they feed on flowers, it stunts the plant’s growth as it is unable to produce fruit.
Eating blister beetles can be fatal for animals because of the toxins they secrete.
They especially endanger horses and other livestock that often feed on alfalfa hay.
Blister beetles are very common in alfalfa fields, so horse owners should be particularly careful to inspect the hay first.
A large amount of cantharidin and blister beetles consumed even accidentally can cause inflammation, blister beetle poisoning, and even death in animals.
Are They Dangerous To Humans?
As we discussed above, when crushed or injured, blister beetles produce a toxin known as cantharidin.
When it comes in direct contact with the human skin, it can cause irritation and blisters.
If humans ingest them accidentally, it can cause gastrointestinal issues and harm the urinary tract.
How To Get Rid of Blister Beetles Through Natural Ways?
If you find a blister beetle infestation, it is best to use natural and organic ways instead of chemical treatments to remove them.
Diatomaceous Earth
One of the most common and well-known products used is diatomaceous earth (DT). It’s a powder version of a soft, siliceous sedimentary rock that occurs naturally in the environment.
Sprinkling DT near your plants will kill the beetles and prevent new ones from infesting the plants.
Oyster lime shell
You can also use oyster lime shells to repel the blister beetles. While not as effective as DT, you can definitely use it as a preventative measure before planting.
Remove Manually
You can also manually clear the beetles by picking them out of your garden.
However, do not forget to wear gloves if you choose to do this. If you injure or crush them by mistake, the toxins they secrete can irritate and cause blistering on the human skin.
Once you pick the bugs, collect them in a bucket and spray soapy water to kill them.
Neem Oil
You can also try a homemade mix of neem oil in about a gallon of water and some liquid soap.
Spray on the bugs directly and ensure you cover them completely because blister beetles tend to trick you by pretending to be dead.
The neem mixture interferes with the beetles’ need to feed and makes them sterile, stopping reproduction.
Cover Your Plants
Another effective way is to use row covers for your plants. You can either use framed screens or plastic sheeting.
The ideal time to put down these row covers would be after you plant your saplings and before it’s time for pollination.
Birds
Birds are major predators of insects, and it’s no different for blister beetles.
Attracting birds to your gardens with bird feed and water will ensure they pick blister beetles from your plants.
Keep Out Grasshoppers
Blister beetles (more specifically, their larvae) love feeding on grasshopper eggs and weeds such as pigweed, ironweed, and ragweed.
The adult beetles feed on fully-grown grasshoppers.
Keeping these weeds and grasshoppers out of your garden automatically keeps blister beetles out.
Using Chemical Methods For Blister Beetle Control
Please try to use natural and organic ways and products to eliminate garden pests.
However, if the infestation is very strong, only a chemical treatment will help you deal with it.
Spinosad sprays are the most commonly used chemical treatment to eliminate blister beetles.
Spinosad is a biopesticide that will kill blister beetles within 24-48 hours.
It also breaks down into harmless ingredients after two days of exposure to sunlight. This makes it safe for other animals and birds.
However, make sure you keep it away from the water supply.
Group 1 and 3 insecticides, commonly known as Carboryl, lambda-cyhalothrin, and gamma-cyhalothrin, are also considered effective when dealing with blister beetles.
Do not use these when plants are in full bloom, though.
How To Prevent Blister Beetles From Coming Back?
Blister beetles tend to feed on pigweed, ironweed and ragweed.
By maintaining your garden/field and keeping these plants from growing, you can make sure blister beetles stay away from your plants.
Grasshoppers are a delicacy for blister beetles. If you spot several grasshoppers in your garden or field, it’s best to inspect the grounds for their eggs as well.
The larvae of this bug feed on grasshopper eggs, and the adult blister beetles feed on adult grasshoppers.
So, if you wish to prevent a blister beetle infestation, ensure that you keep weeds and grasshoppers at bay.
Frequently Asked Questions
How do you get rid of blister beetle infestation?
There are several natural ways to get rid of a blister beetle infestation.
For example, you can use diatomaceous earth or oyster lime shells on them.
If there are only a few, you might also pick them up one by one (with gloves protecting your hands).
After that, just put them in soapy water, and they will die off automatically.
Neem oil is another good way to get rid of these pests.
What are blister beetles attracted to?
Blister beetles are attracted to light, especially ultraviolet (UV) wavelengths. This means that they often congregate around artificial lighting sources at night.
They also feed on grasshoppers and other small insects.
Blister beetles are most active during the warmer months of the year and can be found in large numbers in fields after sunset.
Why do I have blister beetles?
Blister beetles are a common pest problem that can occur in gardens and agricultural crops.
They feed on plant material such as leaves, stems, and flowers. When populations get too high, they can cause serious damage to your plants.
In addition to feeding on the foliage, blister beetles produce a chemical when disturbed that is released from their bodies, causing blisters and sores.
This chemical irritates other organisms, including humans, and can cause discomfort and irritation if handled without proper protection.
What happens if you touch a blister beetle?
Touching a blister beetle can cause skin irritation or dermatitis due to its toxic chemicals called cantharidin.
These chemicals are released as a defense mechanism when the beetle is disturbed.
Cantharidin causes inflammation and blisters with contact, hence its name.
Some people have experienced itching, swelling, and redness on areas of skin exposed to the bug’s exoskeleton.
This may last anywhere from a few hours to several days, depending on the severity of the contact.
You also should be aware that these beetles also release a foul odor when agitated as another defense mechanism.
Wrap Up
Blister beetles are garden and crop pests that secrete toxins harmful to animals and humans. They can also destroy flowers and vegetables by feeding on them.
There are several manual and chemical ways to get rid of them. You can use diatomaceous earth, oyster lime shell, and neem spray as natural repellants. You can weed them out manually too.
In terms of pesticides, you can use spinosad sprays to kill a blister beetle infestation.
Thank you for reading!
Reader Emails
Blister beetles occur in many colors and varieties. Our readers have captured a lot of their pics over the years.
Please go through some of the photographs, and the details of how dangerous these pests can be to weeds and animals
Letter 1 – Blister Beetle
AWESOME site!
The other I have no clue what it is. It was taken on the shore of Lake Michigan at the Sleeping Bear Dunes National Lakeshore…there were hundreds of these hanging around. Any idea?
Josh in Detroit
Hi Josh,
One of our beetle experts Dan, says this looks to be one of the Meloid Blister Beetles. The genus is Epicauta, the species indeterminate. The family includes the European Beetle that is used to make the aphrodesiac Spanish Fly.
Letter 2 – Blister Beetle
Hello,
We would like to know what kind of beetle this is. We found him on a wild rose bush in the desert scrub near Drumheller Alberta. He is green on his underside, legs and head and has purplish wings. He is about an inch long not including his antenna.
There is a photo matching your specimen posted to Bugguide, and Eric Eaton wrote: “One of the blister beetles in the genus Lytta, possibly L. nutalli or L. cyanipennis.” Perhaps one of our readers can provide an accurate identification for this positively gorgeous Blister Beetle.
Letter 3 – Ash Gray Blister Beetle
I took this picture of an ashgray blister beetle, they are taking over my hostas. There are at least 100 of them in all sizes. Thought you might like this picture
Shelly
Savannah, MO
Hi Shelly,
Thanks for sending your photo of an Ash Gray Blister Beetle. We have found it listed online as Ash-Gray Blister Beetle Epicauta fabricii. Bugguide also has a nice photo of the species.
Letter 4 – Blister Beetle
Saw this guy at the Rockhound State Park near Deming, NM in late November 2006. It is a desert area, and there were lots of the familiar Darkling beetles with their raised hindquarters in the vicinity. We have those at home (in So Cal) and I am very familiar with them. This particular beetle however I have never seen before. The photo shows it at about 160% size. Thank you,
John Subik
Temecula, CA
Hi John,
This is a Blister Beetle in the genus Megetra.
Letter 5 – Blister Beetle
hello,
i saw this bug crawling around at an airport in texas. i couldn’t find it online or on your site. the local guys called it an “armadillo bug”, but a google search for that did not turn up any results. can you tell me what it is? thank you and nice site.
kitty hawk
Hi Kitty,
This is a Blister Beetle in the genus Megetra. Many Blister Beetles secrete Cantharidin which causes blistering of the skin.
Letter 6 – Blister Beetle
Found a couple of these. Suspect they are common but cant find them in my books. Please enlighten me. Thanks
Lonny
Hi Lonny
This is some species of Blister Beetle from the family Meloidae. It is not a perfect match to the Iron Cross Blister Beetle, but it is probably the same genus, Tegrodera.
Letter 7 – Blister Beetle
Hi:
We found this bug on the road in our neighborhood. We live north of Prescott, AZ at 5000ft. in high desert terrain. I’ve attached a photo of it. We let it go, so I hope it isn’t rare! Thanks,
The Stoddard Family
Dear Stoddard Family,
This is a Blister Beetle in the genus Megetra. According to BugGuide, this genus “Restricted to Chihuahuan Desert of the USA (TX, NM, and extreme southeastern AZ) and Mexico (where most of this desert region is located).”
Letter 8 – Blister Beetle
This was taken in Gardner, MA and I’ve never seen one of these
before. What is it??
Lori
Hi Lori,
It is definitely a Blister Beetle in the family Meloidae,
but we are not certain of the genus. It looks most like the
Oil Beetles in the genus Meloe, and there is one image on
BugGuide
that looks quite close. We will see if Eric Eaton can assist.
Letter 9 – Iron Cross Blister Beetle falls into swimming pool
Sat, Apr 18, 2009 at 1:35 PM
I have lived in Arizona for awhile and have never seen a bug like this until recently I noticed a bunch in our yard and floating in the pool. I am wondering if this is a Blister Beetle.
Melissa
Queen Creek, AZ
Hi Melissa,
You are correct. This is an Iron Cross Blister Beetle in the genus Tegrodera. Of the three species posted to BugGuide, Tegrodera aloga is the one that has been reported from Arizona. The members of this genus are also known as Soldier Blister Beetles. Through the years, we have gotten so many reports of critters that have fallen into swimming pools that we want to have a small section of our book cover those incidents. Your photo is quite beautiful.
Letter 10 – Blister Beetle
August 17, 2009
I have been seeing this unidentified bug on my walks for the last 3 or 4 years. They are usually walking across the road. The photos were taken in the evening at sundown. The bugs were climbing up to stay in the sun, and on the rocks they were finally being still enough to take good photos. I have not noticed them eating the vegetation. These bugs are as large as I have seen them, about 1 inch long. They drag their long abdomen leaving a very specific track.
The wings are hard, shiny, and dimpled like orange peel; very beetle like, and useless. The head looks like an ant head, without large pincers. I have more pictures if you want them.
What are they?
Rebecca, Cuba, NM
Cuba, New Mexico
Hi Rebecca,
This is a Blister Beetle in the genus Megetra, and sadly, it has no common name other than the general family name of Blister Beetle. According to BugGuide: “Range Restricted to Chihuahuan Desert of the USA (TX, NM, and extreme southeastern AZ) and Mexico (where most of this desert region is located).” In the past, we received a submission from Spain that looks very much like the genus Megetra, and is probably in the same tribe, Eupomphini. You should use caution if handling a Blister Beetle as they can release a compound cantharidin which is a blistering agent.
Letter 11 – Blister Beetle
May 30, 2010
Noted in Southeast NH on May 29th about 4PM. It was crawling on top of my pool filter. Haven’t seen this one before.
boxav8r
Lee, New Hampshire
Dear boxav8r,
The distinctive coloration identifies this beetle as Lytta sayi, one of the Blister Beetles without a common name, though some texts may refer to it as Say’s Blister Beetle. According to Bugguide, it is found in the Northeastern portions of North America.
Great answer! And fast! Thank you. Pete
Letter 12 – Ashgray Blister Beetle
Location: Georgetown, TX USA
June 30, 2011 9:06 am
I have / had a very nice butterfly weed plant that has become infested with these dusty greenish grey bugs that have stripped the leaves and flowers off of about 75% of the plant – I have not seen this bug before nor can I find it anywhere on the internet – please help if you can.
Signature: Melissa
Dear Melissa,
We believe we have correctly identified your beetle as an Ashgray Blister Beetle, Epicauta fabricii, based on photos and information posted to BugGuide. We don’t know what your butterfly weed is, but here is what BugGuide indicates are the foods for the Ashgray Blister Beetle: “Adult hosts: commonly on Leguminosae, including alfalfa, Baptisia, bean, pea, and sweetclover; sometimes attacks potato and glandless cotton.” On the BugGuide Family page for Blister Beetles, it is indicated that “Larvae are parasitoids. … Epicauta (and other genera) larvae prey on eggs of grasshoppers.” Insect populations do not remain consistent from year to year. Some years see a surge in populations, and it can generally be associated with a plentiful food supply. We can only speculate that perhaps last year there was a plentiful population of Grasshoppers, and that the eggs they produced allowed for a high survival rate among Blister Beetles. Plants that are defoliated by insects generally survive and new leaves are produced by the plant to replace the lost leaves. We would also caution you to handle Blister Beetles carefully as the beetles can produce a substance, cantharidin that is a blistering agent should it come into contact with the skin.
Thank you so much! – Yes we had tons of grasshoppers last year and have them again this year so I know what to look out for – too bad for the adults because I would like them to eat all the grasshoppers they can but I want to try and save my butterfly weed!
Thanks again!
Melissa
Letter 13 – Ash Gray Blister Beetle, not Longhorn
Subject: Mecas cineracea – Unrepresented!!!
Location: San Antonio, TX
July 21, 2013 9:08 am
Hi, guys,
I sent this to you last week, but I know you’re super busy, so I kept looking. I found the wonderful TexasEndo.net site, and with the help of its Longhorned Beetle page, I think I may have found my guy! Sure looks a lot like Mecas cineracea Casey, according to the pic, which links to BugGuide. (Link:http://bugguide.net/node/view/510871) I searched for other Mecas members in your archives, but didn’t find any, at least not identified down to the species level, so I am sending them in again. Hope I’m right! (Frankly, I’ll be ecstatic to be close.) He was an inch and a half long, and looked to have a suede texture. (Described on BugGuide as ’ashy’.)
Signature: Melvis & Laugh
Ed. Note: Here is the original message:
Subject: Stylish Suede Leather-y Beetle
Location: San Antonio, TX
July 15, 2013 3:53 pm
Hi, guys,
I met this new friend this morning and snapped a few pics for you. He was sitting on an old pallet. The greenish-gray color was a perfect match for the weathered wood, and he had a great texture that resembled suede. I looked around BugGuide for a while, but there are so many beetles, my head was spinning. I hope you have better luck and enjoy this guy. He was robust, about an inch long, and has a distinctive set of markings.
Signature: Melvis & Laugh
Dear Melvis and Laugh,
We dug through our unanswered mail to locate your original message, and we are including that as part of this posting. Your searching led you to a member of the Longhorn Beetle family, Cerambycidae, but the beetle in your photo is actually a Blister Beetle in the family Meloidae. We believe it is either an Ash Gray Blister Beetle, Epicauta fabricii, or a close relative. So, though your identification is incorrect, both beetles could be described as “ashy” which might have led you to the wrong conclusion.
Daniel,
While I’m disappointed that I got it wrong, I’m glad that you got it right! And I’m glad that I didn’t pick it up to feel the texture!! (I was tempted.) Thanks a lot for all you do!
Letter 14 – Blister Beetle from Spain: Berberomeloe insignis
Location: almeria spain
May 5, 2014 1:16 pm
Hello,
Ive looked at the other pictures you have of this beetle but the ones I found in our garden are slightly different.
They dont have the strips or wing, just complety black body with a bright red head.
We live in almeria spain.
Signature: Laura
Hi Laura,
Through a somewhat convoluted path, we believe we have correctly identified your Blister Beetle as Berberomeloe insignis. We started by searching our archives and we located an all black Blister Beetle and a tentative identification as Berberomeloe insignis, but the link we originally used in 2010 is no longer active. Upon searching the name, we discovered several images of a red eared Blister Beetle that looks very much like your individual, including this image on Los Bloggers de Axena. Additional searching led us to a marvelous pdf on magrama.gob.es, which we figured out is a Spanish government website, but alas, our Spanish is rather insufficient to grasp the totality of the information it provides. At least we know that Berberomeloe insignis is endemic in southern Spain, and your town Almeria is included in the range.
Letter 15 – Black Blister Beetle
Geographic location of the bug: Southwest New Mexico
Date: 09/21/2021
Time: 11:03 AM EDT
Your letter to the bugman: We found these insects while hiking in the Gila National Forest, Saddle Rock Canyon; 10 miles NW of Silver City. There were hundreds of them on the desert willows – many were mating on the trees. I apologize for the fuzzy image. I hope it’s clear enough for an identification.
How you want your letter signed: Karen Nakakihara
Dear Karen,
This is a Black Blister Beetle, Epicauta pensylvanica, and like many Blister Beetles, they appear seasonally in great numbers for a short period of time each year, with some years seeing far greater numbers. According to BugGuide: “Associated with Asteraceae, such as goldenrods and asters. May damage crops, such as beets, potatoes, tomatoes.” The Black Blister Beetle is pictured on the New Mexico State University website.
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