Blister Beetles
Blister beetles do not have a toxic bite or sting, but if you crush one of these pests you can wind up with small blisters on your skin several hours after contact due to the secretion of cantharidin (a toxic compound in their bodies).
Grey blister beetle (top left), Black bister beetle (top right)-photos United Agri Products
Description
Blister beetles have very long thin cylinder-shaped bodies with large heads. They are about 2 cm long (from ½ to 1 inch in length) and relatively easy to identify because of the distinct “neck-like” section between the body and the head. They usually fly around in groups and there are many types of them. They are grey, black and striped with some species shiny black-blue, or black-green.
Habitat
Blister beetles are found in most parts of the US and most parts of Canada. It is the adults that cause most of the damage. Fortunately however they don’t stay around an area too long so the best control is to let them run their course unless infestation is severe. They overwinter as semi-pupae in the soil and emerge in the spring and molt. Adult blister beetles emerge in the summer months.
Life cycle of blister beetle-NC State University
Diet & Damage
Blister beetles eat the leaves and flowers of most plants… peas, beans, potatoes, turnips, tomatoes, many other veggies and flowers. They can defoliate plants in no time. The larva have been known to eat grasshopper eggs so they are somewhat beneficial. In some cases where these beetles are severe on alfafa, farmers must take caution when cutting as their livestock can die from ingesting dead blister beetles. The condition that affects livestock after eating grains infested with these beetles is called Cantharidiasis
Control
1) Hand Pick
Be sure to wear gloves or use tweezers as they can release a substance that causes blisters on the skin. Drop them in hot soapy water. Be sure not to touch them even when they are dead as they can still cause painful blisters on your skin.
2) Keep Weeds Low
Weed around edges of your garden attract blister beetles because of grasshopper eggs. Eliminating the weed problem will help control infestation.
* A word of warning, killing them is not a good option unless you dispose of the bodies. Their poison stays in their bodies long after they are dead.
June 19th, 2007 at 10:08 am
I used to live in south Texas. This bug would get on me. It would leave a bister
on me. If I open the bister it takes a week or so to get well. If you leave
it alone it would go a way in two to three days. Corky
August 20th, 2007 at 9:30 am
Blister beetles are nasty! They get into my horses hay and then my poor babies get huge nasty ulcer-like blisters on the insides of their mouth. It takes weeks to heal because a horse can keep their mouth very clean. I’ve had two get them so far (in one year). It nice to have a place to get info about them, though…great site!
-Kim
Southern California
July 6th, 2008 at 12:14 am
July 5, 2008 – North Texas
My son has a long blister on his right shoulder, about 3-4″, which looks like a bug has crawled accross his skin, cutting through the skin and leaving a trail of blister-looking material. The first day it was fat like a bubble blister, but long. It has gradually started drying up, but today is day three and it still has small blisters. We have doctored it with 2% anti-itch hydrochloride, and he has tried not to bother it.
He found a dead bug in another room which resembles the bugs in the pictures.
Please respond if there is anything else we can do.
July 6th, 2008 at 9:46 am
I’d take him to the doctor. It sounds like it’s infected and should be treated. Some people have allergic reactions to bites like this.
August 18th, 2008 at 12:27 pm
I thought this article was mainly about the destructive nature of the blister beetle and not neccissarily about the effects of the toxins on the skin. I would like to know more about organic methods of controling or wiping out this particular garden monster as they are eating our eggplant plants and it is very labor intensive to hand pick.
October 30th, 2008 at 12:38 pm
wow, great site for information, i been doing pest control in england for years and i have never heard about some of these pests your talking about, its great
April 9th, 2009 at 11:52 pm
Thank you for the information. I have looked up several websites about these blister beetles, none of which gave me any methods of getting rid of them.
August 2nd, 2009 at 7:12 pm
Great info. Found them on my tomato plants in Williamsburg, VA. They drop when bothered so I used a tin can to catch them. Then I terminated them with rubbing alcohol. Good to know about their toxicity. I did not crush them but I did touch them so I might be in for some blisters. Thanks.
August 16th, 2009 at 10:01 am
Thanks for the info! I just found these buggers eating their way through my hostas! I hand picked as many as I could & will keep an eye for more. And of course wear gloves when I handle them.
September 2nd, 2009 at 7:00 pm
I need help treating myself. I have blusters all over and they are now really red and look infected. I have been to 3 doctors and no one can help me . They haven’t heard of these beetles. Please help me . I am having a severe allergic reaction!
September 6th, 2009 at 8:02 pm
My son turned up with this awful blister on the side of his foot which just got bigger and bigger. The pediatrician thought it was a staph infection so he popped it to get a culture. My son then got three more huge blisters on the bottom of his foot. I learned about beetle blisters and was told to pop the new ones, but don’t touch the liquid. I popped the blisters (and wore gloves), but my 11 year old touched the liquid. He now has bumps forming on both hands and some new places on his foot. Could these blisters really be from the liquid inside his first bite? I will take him to a dermatologist this week. And, if we can just leave the blisters alone and not pop them, will they really dry up?
September 6th, 2009 at 9:16 pm
Jennifer
I am not a doctor but if is the case then get them straight to the hospital
September 19th, 2009 at 2:49 am
To laura. regular medical doctors never know the problem when it comes to skin like problems. go see a dermatologist (skin doctor).
September 23rd, 2009 at 6:40 pm
So this is what’s getting my tomatoes! And it’s what left a blister on me just under my right eye today! Just thankful it didn’t happen inside my eye–didn’t miss it by much! Scared to go back out and check the tomatoes again. And to let my cats out!
November 28th, 2009 at 1:14 pm
I got these a couple times when I was young, so did a couple of my siblings. As I recall: VERY painful blisters, which would enlarge over the first few days. But DO NOT pop them! No matter how careful you are, you will get a little of the fluid on another area of skin, and then that area gets the same symptoms (blisters enlarging over a few days). I remember the symptoms being gone in less than a week when I was about 10, but it took almost 2 weeks when I was 18. Maybe a different species of the bug, or the difference in age, who knows? Now, I think I’d be asking my doctor for strong lidocaine patches or gel, if available. Those blisters were many times more painful than any other blister I’ve ever had.
January 23rd, 2010 at 9:28 am
Hellish bugs, but they do have some odd weaknesses, in my experience. For example, they hate noise. Banging on a piepan or loud rock music nearby will make them move, as will repeatedly shaking the leaves of the plants with a small tree branch or such. But don’t touch ‘em. And don’t mow or weedeat near them, as the blistering agent can end up anywhere. My two cents from the Missouri Ozarks.