Blister Beetle Bites
Several species of blister beetles are found in the U.S. Their appearance varies, but most are about 1 to 2.5 cm in length. Some are brightly colored with yellow or orange, while others are a dull gray. They often are encountered at exterior lights in the evening or on flowers in grassy fields. Blister beetles use a potent chemical defense to protect themselves from being eaten by predators. Even though humans are not predators of blister beetles, they also may be affected if they encounter these insects.
Blister beetles internally produce a chemical named cantharidin. The beetle does not have a stinger with which to deliver the chemical and is incapable of delivering an injurious bite. However, cantharidin can cause blisters or form welts on exposed skin. This can occur when someone crushes a beetle walking on their skin. Blisters form within a few hours of contact, but typically do not result in any lasting skin damage or scarring.
Cantharidin does have some beneficial uses for humans. For example, certain wart removers contain a form of cantharidin to burn away the wart.
Blister Beetle Bite Treatment
Blister beetles are not a usual household pest. Since often they are encountered in fields and other outdoor areas, an exterminator is not required. The best approach to reduce the likelihood of exposure to blister beetles is to take precautions like wearing long-sleeved shirts and pants when in areas where you are likely to encounter them. If a blister beetle is encountered, do not crush it. Instead, gently remove it.
Most cases of exposure are not life threatening and do not result in permanent skin damage. However, an area of particular concern would be the eye. If a person crushes the beetle and rubs their eye, they can spread the cantharidin to their eye. Should this occur or the person has any medical concerns, they should consult their physician for guidance.