Blister beetles can be dangerous, even fatal to animals. But what about us? Do blister beetles bite humans too? And what are the effects of their bites? We cover all of this below.
Blister beetles are a fascinating group of insects found all over the world.
They vary in size and color but are most commonly black or orange and less than an inch long.
The big question when it comes to these bugs is: do they bite?
Well, the answer is no.
While some species of blister beetles will pinch if provoked, they typically don’t bite humans.
In this article, I will explore the behavior of blister beetles, the potential dangers, and what to do if you come into contact with one.
Are Blister Beetles Dangerous?
Blister beetles are dangerous as they secrete a defense liquid that contains cantharidin.
This is an irritant and is powerful enough to cause severe burns or blisters on exposed human skin.
That being said, these risks rarely occur in day-to-day life unless you come into direct contact with the bug.
Do Blister Beetles Bite or Sting?
Blister beetles don’t typically bite or sting, but direct contact can cause blisters, as we mentioned.
Blister beetles release a chemical defense called cantharidin.
This stuff is poisonous to animals and can lead to skin inflammation if it contacts human skin.
The allergic reaction caused is known as “blistering” and can be very uncomfortable.
Thankfully, blister beetles do not actively seek to bite humans or animals, but they can inadvertently cause a lot of harm.
Are They Poisonous/Venomous?
Blister beetles are not venomous. However, they do contain cantharidin which can be toxic if ingested.
Cantharidin is used by species of blister beetles as an effective defense mechanism against predator attack.
Ingestion of cantharidin can lead to nausea, vomiting, abdominal pain, headache, and even shock in large doses.
Direct contact with blister beetles will only cause skin irritation.
Ultimately, people should take caution when handling these insects, as their toxicity should not be taken lightly.
How To Treat Blister Beetle Bites?
If you’ve experienced a blister beetle bite, you’ll likely experience some key symptoms.
The most common is a red bump accompanied by sharp pain and itching. In some cases, multiple bites can result in swelling, body aches, and a blister-like appearance.
Treating blister beetle bites can be an unpleasant experience.
Fortunately, there are some simple steps you can take to help soothe the reaction.
To provide relief, apply an over-the-counter hydrocortisone cream or calamine lotion to the affected area.
Ensure to clean the affected area with mild soap. Next, thoroughly rinse off any remaining residue.
Taking an antihistamine like Benadryl can also help reduce inflammation and itching.
You should avoid scratching, as this could increase pain and lead to a skin infection.
Additionally, it may be helpful to apply ice or cold compression to the area. This will help alleviate pain and reduce inflammation.
Taking an anti-inflammatory medication such as ibuprofen could relieve symptoms associated with blister beetle bites.
Sometimes, a physician may prescribe antibiotics or medicated ointments for more severe reactions.
If you are experiencing serious allergic reactions, such as difficulty breathing or swallowing, seek medical attention immediately.
Overall, it is important to take precautionary measures when dealing with blister beetles to avoid potential contact with their toxins.
How To Avoid Blister Beetles In Your Home/Garden?
The best way to avoid blister beetles in your home or garden is to be proactive.
If you own horses or have alfalfa hay in your garden for any other purpose, be especially vigilant.
Check for signs of them frequently, such as beetle larvae and adult blister beetles around the house.
Move the vegetation away from any openings in your home or basement.
Inspect stored items like firewood and mulch since these can sometimes harbor insects.
Handpick any beetles you see and dispose of them promptly.
However, it may also be necessary to use insect controls like sprays, dust, or baits if a serious infestation develops.
Additionally, keeping debris piles away from your property can help prevent an infestation.
Blister beetles usually congregate in them and move into your yard.
Taking all of these steps can significantly reduce the risk of encountering one of these critters!
Should You Pop Blister Beetle Blisters?
Blister beetle zits can be extremely irritating and uncomfortable.
Generally speaking, it is a good idea to resist the urge to pop them.
Puncturing them could cause additional discomfort and risk of infection.
Instead, applying an anti-itch cream can help relieve any itching or burning sensations you may experience.
Frequently Asked Questions
What happens if you touch a blister beetle?
If you touch a blister beetle, you may experience intense pain and irritation on your skin.
Blister beetles contain cantharidin, which is a toxic chemical released when the insect is disturbed.
This acidic secretion produces a severe burning effect wherever it comes in contact with your skin as well as causing redness, blisters, or welts.
If large amounts of cantharidin are ingested, it can be dangerous, so it’s best to avoid touching blister beetles if possible.
What does a blister bug bite look like?
Blister bug bites usually cause redness, swelling, and a hard bump or blister with an itchy patch at the site of the bite.
The blister may be clear or filled with a whitish fluid.
Blister bugs can also cause fever, rash, and general sickness in some cases.
Additionally, the area around a blister bug bite may become red and swollen over several days after the bite occurs.
How do you treat a blister beetle bite?
First, the area should be washed gently with soap and water.
To further reduce irritation, an ice pack should be applied for 20 minutes at a time.
If pain persists, a topical anesthetic or steroid cream can be used as directed on the product label.
As with any insect bite, seek medical attention if symptoms persist or if there is excessive swelling, redness, or pain.
Where do blister beetles live?
Blister beetles are found throughout much of the world. They inhabit a variety of ecosystems, including grasslands, deserts, and forests.
The most encountered species live in temperate regions in the US, Mexico, and Canada.
Some species are also present in South Asia, South America, Europe, Africa, and Australia.
Blister beetles prefer warm climates and can frequently be found attracted to lights at night during summer months.
Their favorite habitats include alfalfa hay, but any place where they can find grasshoppers is usually good for them.
In conclusion, blister beetles can bite if handled carelessly or disturbed by a human.
They are often founds in fields where they can get access to grasshoppers or in alfalfa hay, which is one of their favorite haunts.
Although the bite is usually harmless and doesn’t cause any major health concerns.
If you’ve been bitten by a beetle, it’s best to apply antiseptic cream to limit skin inflammation.
It is wise to take preventative measures to avoid contact with blister beetles whenever possible.
By taking preventative measures, you can protect yourself from the harmful effects of blister beetle bites.
Getting exposed to a blister beetle’s touch can be quite a bad experience, which is why a lot of people seem to confuse them with stinging insects.
It is actually not their sting that makes them dangerous – it is the cantharidin secretion that causes blisters.
Read on to see some pictures of blister beetles sent in by concerned readers worried about their bites.
Letter 1 – Blister Beetle
Please help identify bug^-^)
I love your site, and looking at all the bugs. I really missed my chance to work my love of bugs into a career. I have not been able to find this bug’s identity and after seeing your site think you will. I am in northern Arizona, near Prescott. We are in high desert landscape. they like to eat little tiny fleshy weeks you can see in the picture. There are many of them in the yard, not as dense as the blister bug swarm we experienced a few years ago, but you cannot walk around the yard without stepping around several each time. In the pictures their stripes look red, i think they are more orange in the sunlight. I put my finger next to him to show size.
Thanks in advance for any help.
The “blister bugs” you mention in your letter are probably Blister Beetles in the family Meloidae. The insect in your photo is also a Blister Beetle in the family Meloidae, and in the genus Megetra.
Letter 2 – Blister Beetle
Large, dark green beetle with red legs
Sat, May 23, 2009 at 1:47 PM
I found this beetle on my apple tree on May 23. Can you identify it?
This is a Blister Beetle, most likely Lytta sayi according to some photos posted to BugGuide.
Letter 3 – Blister Beetle
Black insect with red stripes
July 16, 2009
Found this bug east of flagstaff in an abandon trading post. It was moving quickly but seemed to be dragging that red striped sack.
30 miles east of flagstaff arizona
This is a Blister Beetle in the genus Megetra. You can see more images and get information on BugGuide. We love your photo with its alarming color palette. The Blister Beetle does have warning colors for a good reason. It can exude a blistering agent called cantharidin.
Letter 4 – Blister Beetle
Found in Prince Edward Island, Canada
October 14, 2009
Hello! I was happy to find your site today! What a lot of wonderful and informative information!
Last summer on vacation, I snapped a nice photo of a most interesting flying insect. I still have no idea what it is. It was June and we were on Prince Edward Island, Canada.
There were many of these harmless and beautiful creatures flying among the lupines along the edge of the roads.
We enjoyed their magnificent beauty! I was so happy my not-so-great camera allowed me this beautiful shot of this fellow (or lady, as the case may be). They were about 2 inches long or so. Not tiny!
I would love to know what it is and what its habits are.
Thank you for all you’re doing!
Prince Edward Island, Canada.
This is a Blister Beetle, probably Lytta sayi. You can find other photos and information on BugGuide. Also, the entire family of Blister Beetles, Meloidae, includes members that are characterized by the following BugGuide description: “Pressing, rubbing, or squashing adult blister beetles may cause them to exude their hemolymph (‘blood’), which contains cantharidin. This compound causes blistering of the skin, thus the name blister beetle. Accidental or intentional ingestion of these insects can be fatal. There are documented incidents of horses dying after eating hay in which blister beetles were inadvertently baled with the forage. Watch that curious children do not attempt to put these beetles in their mouths. The external use of cantharidin, commercially known as ‘Spanish fly,’ the supposed aphrodisiac, is likewise discouraged.“
Letter 5 – Blister Beetle
Appears to be Nemognatha sp
January 13, 2010
Found in the holes bored for Mason Bees
Want to know if this is Nemognatha or another sp. If Nemognatha what species?
We are going to contact Eric Eaton, who lived in Oregon, to see if he knows what species of Blister Beetle you have found. The genus Nemognatha is one in which, according to BugGuide, the “Females lay eggs on flowers, larva attach themsleves to bees when they visit flowers and are then carried to bee nests where they eat bee eggs and stored food.“ That would explain finding this specimen in a Mason Bee nest.
I think it also may be Tricrania (stansburyi), a closely related genus, as I did a little more research after sending it to you. It sure would be nice to find out for sure,
Eric Eaton concurs
I agree with Jake, this is a specimen of Tricrania stansburii (spelling taken from Hatch in Beetles of the Pacific Northwest). Nice find!
Letter 6 – Yellow Crescent Blister Beetle
Unidentified bug (Beetle??) eating my maroon bluebonnets
May 17, 2010
I found several of this insects lunching on marroom bluebonnets on 5-15-10. They were not eating anything other than those blooms and they devoured them. I thought perhaps since maroon bluebonnets are not native to this area they can’t fight off the bugs????
Thanks for your help.
Ennis, Texas North Central Texas
We are nearly certain that this is a Yellow Crescent Blister Beetle, Pyrota insulata, based on photos posted to BugGuide where it is stated: “Adults feed on nectar, mostly Honey Mesquite (Prosopis glandulosa) though also observed on Rattlesnake Master (Eryngium yuccafolium) and probably others.“
Thanks so much for the information. They were feeding on more than nectar…….
Letter 7 – Blister Beetle
Is this a Blister Beetle?
June 14, 2010
This is a photo i took this weekend of just a couple of the beetles in out lupine patch, I was informed that they might be Blister Beetles. There were hundreds of them all over the flowers.
A Page-N-Thyme Farm Anson, Maine
Dear Page-N-Thyme Farmers,
You are correct. These are Blister Beetles. Alas, we cannot confirm their identification on BugGuide because the page is currently unavailable, but we matched it to a photo we posted recently from New Hampshire. It appears it is Lytta sayi, a species with no common name.
Letter 8 – Blister Beetle
What a colorful beetle
Location: Little Colorado river, Apache Co. AZ
August 8, 2010 10:58 am
Found this speciman near Springerville on a path along the Little Colorado River.
Is the abdoman distended because it is about to lay eggs?
This is a Blister Beetle in the genus Megetra and you are to be commended for even recognizing that it is a beetle as its morphology is very different from the typical beetle. BugGuide does not have any explanation for the distension of the abdomen but it seems to be a characteristic of the genus.
Letter 9 – Blister Beetle
Oklahoma Blister Beetle? Husband says yes…
Location: Seminole, Oklahoma
August 8, 2010 2:36 pm
I found this great looking beetle and stuck it into a bowl until I could grab my camera. I took many pictures of it, but ended up with only 8 that were in focus. It was hanging around the cat food bowl (before I captured it). When I let it go it was in a hurry to get away from me. The bug was approximately 1.5” long, and the closest beetle on your website or Bugguide.net I found in looks is the Master Blister Beetle, but mine has a black head. The Master seems to have a red head. My husband insists it’s a blister beetle though. Thanks in advance!
P.S. – I released him and let him go on his way!
You are correct. This is a Blister Beetle, but we need to research the species. We quickly found a match on BugGuide with Epicauta conferta, a species reported from Oklahoma and Kansas. Thank you for contributing a new species to our archives.
Letter 10 – Blister Beetle
What is this bug?
Subject: What is this bug?
Location: Fort Bliss, Texas
October 30, 2010 8:07 am
Found crawling on my brothers leg at fort bliss in Texas….
This is a Blister Beetle in the genus Megetra, a group that is “Restricted to Chihuahuan Desert of the USA (TX, NM, and extreme southeastern AZ) and Mexico (where most of this desert region is located)” according to BugGuide. You were wise to handle this Blister Beetle with gloves because the family is capable of exuding hemolymph that contains cantharidin, a chemical compound that can cause blistering of the skin.
Letter 11 – Blister Beetle
help to identify
Location: West Texas, USA
July 9, 2011 1:26 pm
Do you know what kind of bug this is? A friend found it. Very Curious!
This is a beautiful Blister Beetle, and a species we have not encountered before. We identified it as Epicauta atrivittata on the BioLib website.
Letter 12 – Blister Beetle
The web was no help
Location: New Mexico off I40 west of Continental Divide.
August 6, 2011 8:32 pm
I just wanted to know what it is that I found here. It moved quick so no great shots but, this is what I’ve got.
Please don’t bash the internet. It brought you to us and we are telling you that this is a Blister Beetle in the genus Megetra. You can find images in our archive as well as on BugGuide, which indicates they are: “Restricted to Chihuahuan Desert of the USA (TX, NM, and extreme southeastern AZ) and Mexico (where most of this desert region is located).”
Thanks for the quick response. I don’t usually bash the web but, in this case, my searches were fruitless. Usually having great success with web searches, I was just a bit frustrated to have to get help in the matter.
With an insect, knowing where to begin a search or which key words to search is often critical for a fruitful result. We are glad you got your answer.
Letter 13 – Blister Beetle
Subject: Red and Black Plant Bug?
Location: North Central Florida
September 19, 2012 11:29 pm
I enjoy finding new insects in my yard and getting photos of them. This guy was hanging out on some wildflowers along my fenceline in North Central Florida. I’d love to know what he actually is, I am guessing he is a true insect and possibly one of the plant bugs.
Letter 14 – Blister Beetle
Subject: What is this bug?
Location: Albuquerque, NM
October 10, 2012 8:32 am
Nearly an inch long, huge abdomen dragging in the dirt behind it, glossy black body with vivid red stripes.
The photos were taken with an iPhone and a little macro lens so my ability to capture a decent image is hindered by the equipment. sorry about the third photo in particular.
Taken October 9, 2012 at around noon mountain time, Southwestern Indian Polytechnic Institute Campus, Albuquerque, NM.
This is a Blister Beetle in the genus Megetra. They can be found in the Chihuahua desert region of Mexico, New Mexico and parts of Texas and Arizona.
Thanks for getting back to me so quickly. I gather from the archived posts that i should avoid touching this type of beetle or suffer its namesake. Thanks again.
Yes, avoid handling.
Letter 15 – Blister Beetle
Subject: What kind of insect is this?
Location: Chino Valley, Arizona
September 2, 2012 10:30 am
Hello bug expert,
I live in Chino Valley, Arizona which is 25 miles north of Prescott in North Central Arizona. Elevation 4800’. Photo taken in late August. These bugs are crawling on the ground but appear to have undeveloped wings. They suddenly appeared in numbers of approximately 1 in a radius of 20’. They are approximately 1” long.
Signature: Roger Eads
This is a Blister Beetle in the genus Megetra, and according to BugGuide, the genus is: “Restricted to Chihuahuan Desert of the USA (TX, NM, and extreme southeastern AZ) and Mexico (where most of this desert region is located).”
I have seen blister beetles but never like this. These have a bulbous wasp-like abdomen. The blister beetles I’ve seen are flat. These show up every year in August during the monsoons and disappear within a month.
I don’t like the thought of blister beetles because we have horses.
Letter 16 – Blister Beetle
Subject: Beetle Identification
Location: Toronto, Ontario, CA
December 26, 2012 12:33 pm
Hello, I found a beetle on a Goldenrod plant on the flower in late Summer. I have tried identifying it myself, but it was not in my two insect field guides, nor was it in the internet. It’s head and abdomen looked similar to Blister Beetles and Oil Beetles, so I did some researching on them. Nothing the same. The closest one was the Margined Blister Beetle, but instead of lines on the perimeter of the elytra, there were blotches on the top instead. After all the researching with no results, I began to think it was a new species of insect. The beetle was approximately two centimeters in length. I found it in Etobicoke, Toronto. The Goldenrod it was found on was just outside a small dirt trail in a large field with small shrubs and almost no trees where few people walk. That day, there were hundreds of Locust Borers out on the Goldenrods as well. Please help, for I have been looking for this beetle’s identity for 5 months now. Thank you!!
Signature: Isaac R.
Thank you for sending a larger resolution image. That 9K file was very tiny. We agree that this is a Blister Beetle, and while we cannot provide you with a species, we believe you were very close with the Margined Blister Beetle guess. It is our opinion that this Blister Beetle, which may have coloration that is an anomaly, is also in the genus Epicauta. You can see many species represented on BugGuide that look very similar to your beetle.
Letter 17 – Blister Beetle
Subject: Beetle ID
Location: New Mexico
June 1, 2013 8:35 am
We have this beetle eating the leaves of just about every plant in our garden. We need help identifying it. The beetle got squished in the capture and photo session, that is the yellow on its side.
Signature: Angela Armstrong
This is a Blister Beetle in the family Meloidae and it should be handled with extreme caution as Blister Beetles secrete a substance, cantharidin, that is known to cause blistering in human skin. See BugGuide for additional information.
Letter 18 – Blister Beetle
Subject: Pretty Bug
Location: Medicine Hat, Alberta, Canada
June 24, 2013 9:58 pm
Hello, my sons and I found this unusual insect in the park near our house in southern Alberta, Canada. We’ve never see one like it before and are quite curious as to what it might be! It was quite pretty with a bright purple, iridescent body and equally iridescent green head.
My Internet searching has turned up nothing – any ideas?
Letter 19 – Blister Beetle
Subject: NE Ohio Beetle ID Request
Location: Greater Cleveland Area
May 6, 2014 5:20 pm
I’ve never seen one like this. It stayed still for a few photos. I’m looking for an ID.
Signature: Tim Spuckler
We believe we have correctly identified your Blister Beetle as Lytta aenea based on images posted to BugGuide.