Tooele Transcript Bulletin – News in Tooele, Utah
image A blister beetle rests on a sunflower in Tooele County.

September 3, 2015
Blister beetles are hazardous whether alive or dead

Intended for the use of defending themselves against predators, the blister beetle was given its name for the hazardous chemical possessed in its body. The chemical is called cantharidin and is known for its capability of blistering skin. Therefore when necessary, the blister beetle reflexively secretes it from its joints and onto the flesh of its harasser. Because of how small and unintimidating most blister beetles are, they’re often underestimated when found feeding on the leaves of various vegetables or on the tops of flowers among gardens.

Though the blister beetle’s hasty defense mechanism can be a nuisance for unsuspecting folks, the lust for alfalfa from various species can be deadly for livestock. If an unknowing infestation of blister beetles invade a crop field, and are then later ground up when it is harvested, it becomes tainted by the cantharidin poison. Therefore, when it is fed to livestock mostly horses, cattle, and sheep, the infected crop which is commonly hay, grain, or alfalfa, can cause severe illnesses, then death.

Animals poisoned from blister beetles can die within 72 hours. Signs of blister beetle poisoning can include blisters on the tongue, bloody urine, diarrhea or colic.

Blister beetles range in size from 1 to 2.5 cm in length, while depending on the species, can be found with bland colorations or a combination of stripes and bright warning colors. There are approximately 3,000 different species of blister beetles worldwide, while there are approximately 400 in North America.

Years ago, apothecaries used to mash blister beetles into a powder for medicinal uses and they called it Spanish fly. Spanish fly was used as an aphrodisiac and other various treatments. Today, it is used to remove warts.

Taylor Lindsay is a writer and photographer of wildlife creatures big and small. She can be contacted at

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