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.
August 6th, 2011 at 9:44 am
Sorry meant to say cages around the tomatoes. If you knock them into the soapy water it does kill them.
August 6th, 2011 at 9:43 am
We had huge infestation of blister beetles (ones w/yellow stripes) and we found that spraying the tomato plant down with soapy water worked in getting them off the plant but then when the soap bubbles went away, they scattered so you stomped on them. It would have been great to knock them into the soapy water but we had cages around the beetles. They destroyed our swiss chard, moved to the kale, almost destroyed our tomatoes, destroyed almost all the pepper leaves, on the sweet potatoes and okra. They love to hide so get rid of the straw or cardboard mulch. We also picked them off by hand at night since they were easier to pick off w/o harm, but my husband did get one on his collar and it gave him 3 blisters which they say will go away. We also sprayed a hot cayenne pepper spray at night which seemed to kill them, too. Good luck!
July 28th, 2011 at 5:00 pm
I had one on the side of my right eye it was horrible every time I open my eye I would rip the scab
July 4th, 2011 at 12:27 pm
WE HAVE BLISTER BEETELS BAD IN OUR GARDEN. WOULD BE IMPOSSIBLE TO PICK THEM OUT BY HAND AS THEY ARE BY THE THOUSANDS. WE SPRAYED AND HOPE THE HAS TAKEN CARE OF THEM. ANY OTHER SUGGESTIONS?
July 2nd, 2011 at 10:05 pm
My 2 year old grandson had horrible blisters on the right side of his neck and shoulder from this bug. His mom took him to the doctor and he popped them. They are about two inches long and an inch wide they look horrible. I have seen these bugs everywhere just didn’t know what they were. Thanks to this web site for the great information and hints on how to take care of him. Thanks to all.
May 13th, 2011 at 5:19 pm
I have the grey blister beetles all over my arizona ash tree and the leaves on the tree are starting to turn brown. Could they be causing the leaves to turn brown and if so what can I use to get rid of them without picking them off? Insecticide……
Thank-you,
sally
January 16th, 2011 at 1:50 pm
That’s an interesting theory although I have never had a cold sore in my life and getting into the doctor on the first day is next to impossible but I will give it some consideration.