Have you been bitten by a blister beetle? Do you know someone who has? There are 2,500 species of blister beetles whose bites have different effects.
The blister beetle can be found all over the United States and in the West Indies. They long in length and can range from ½ inch to 1 long. They vary in colors from metallic green, blue, rusty rose, spotted or striped black and yellow, to a dull gray, brown or black. These beetles have a pronounced neck that helps to differentiate them from other beetles.
Blister beetles contain a toxin called cantharidin or cantharide in their body fluids. Cantharidin causes severe irritation and blistering of the skin. There are no reported cases of human deaths caused by blister beetle bites. If cantharidin is ingested by mammals through grazing, it can be fatal. There are many cases of deaths of valuable horses in Florida that ingested alphalfa that contained blister beetles in the hay. Fatal deaths have been reported in horses more so than in cattle and sheep.
You do not have to be bitten by a blister beetle to receive blisters. When the blister beetle is rubbed, pressed, flicked off or squished, its defense is its blood that is released. This hemolymph carries the cantharidin and causes you to blister without even being bitten. Blisters usually do not occur on the fingers or hands because the skin is thicker. Irritation mainly develops on more sensitive areas such as the neck or arms. Some individuals are more sensitive than others and can immediately develop blisters while other individuals never develop them.
Blister beetles have the ability to destroy crops and can be found primarily on alfalfa, beet, potato and tomato, but they are not limited to just this vegetation. If you own a small garden, the blister beetle can be removed physically while wearing garden gloves or a something similar.
The toxin cantharidin was believed to be an aphrodisiac because its chemical properties when released into the body would affect the entire urinary tract of the victim and through irritation of the urethra would cause priapism--the persistent and abnormal erection of the penis. Cantharidin is the main ingredient in Spanish Fly, which was made by dried, crushed blister beetles and ingested through mixing it in powder form in any drink.
It is possible that blister beetle bites may be fatal to humans if the human develops a severe allergic reaction to the bite as with any other insect. It is recommended with all bites to seek professional medical advice immediately.
Blister beetles are attracted to bright light at night, such as patio lights. When there is reported swarming of these beetles, it is advised to turn off the lights. Medical treatment beyond first aid is usually not needed unless there is an major reaction to the bite. The blistering may be uncomfortable but does disappear over time.