During the past two weeks, I received several inquiries concerning blister beetles. These are insects not to be taken lightly. If handled roughly or crushed against your skin, blister beetles release blood laced with potent irritants called cantharidins. Upon contacting skin these compounds can raise nasty looking blisters. See the photograph at the following web site if you are curious: http://creatures.ifas.ufl.edu/urban/medical/blister_beetles.htm. Blister beetles consuming plants in meadows have been inadvertently bailed in hay and fed to horses and other farm animals. The toxic cantharidins in their bodies can be lethal. Blister beetles are also the source of the aphrodisiac and medicinal compound called Spanish fly. The term Spanish fly references a particularly beautiful European species of blister beetle, Lytta vesicatoria from which cantharidins are extracted.
Blister beetle lore
Much lore surrounds the use of cantharidins as potions of love, healing, and death. Love potions concocted with Spanish fly are said to be potent aphrodisiacs. One remarkable tale I stumbled across related the story of a gathering hosted by the infamous Marquise de Sad. To liven things up a bit, the Marquise decided to slip the guests a little Spanish fly on some sweets. Unfortunately, he miscalculated the effective dose a wee bit and rather than arousing his guests several were poisoned to death. Spanish fly was also used as a medicinal in America’s revolutionary era. The father of our nation, George Washington, had a most disagreeable encounter with the Spanish fly. After taking ill, President Washington was near death on December 14, 1799. As was common medical practice at the time, Spanish fly was applied to his neck in an attempt to draw out the inflammation. The Spanish fly therapy and four bloodlettings on the same day proved a bit too much for our ailing founding father and he expired. Other than packing a nasty wallop of poisons adult blister beetles live rather bucolic lives munching leaves or eating pollen.
Epicauta blister beetles are common visitors to goldenrod.
The larvae of blister beetles are another matter. After hatching from eggs deposited on the ground by the female beetle, tiny larval blister beetles called triungulins get busy finding food. In some species triungulins climb flowers, hop aboard a visiting bee, and hitch a ride. Back at the nest the predatory vagabond jumps off the bee and consumes the developing bee babes and the provisions left by their mothers. How rude! Larvae of other species of blister beetles scurry on the ground and locate nests of grasshopper eggs. Hungry triungulans burrow into the soil and the underground omelet becomes a banquet for the blister beetle larvae. If you see blister beetles on plants near your home or in the meadow in the waning days of autumn, resist the urge to handle or eat them unless you desire a blistering surprise.
References:
Bug of the Week gives a shout out to Adam for providing the inspiration and sharing his beautiful Meloe for this Bug of the Week. To learn more about blister beetles and their lore, please visit the following web sites.
http://creatures.ifas.ufl.edu/urban/medical/blister_beetles.htm
http://insects.tamu.edu/fieldguide/bimg167.html
http://library.thinkquest.org/C007974/2_4spa.htm
http://www.gilderlehrman.org/collection/docs_print/print_inhonorofgeorge.html