Spanish Fly

Spanish fly is a name used for a blister beetle species, especially *Lytta vesicatoria*, and for traditional preparations made from such beetles.

Spanish fly is a name used for a blister beetle species, especially *Lytta vesicatoria*, and for traditional preparations made from such beetles. The term is also used for cantharides, a historical medicinal product associated with blistering and aphrodisiac claims. The substance contains cantharidin, a toxic irritant.

Definition and naming

Spanish fly commonly refers to the beetle *Lytta vesicatoria* and, by extension, to cantharides, the powdered or processed preparation made from blister beetles. Dictionaries note both the insect and the preparation under the same term.

Biology and distribution

*Lytta vesicatoria* is a green blister beetle in the family Meloidae. Sources describe it as native to parts of southern Europe and broadly distributed across Eurasia.

Historical uses

Cantharides were used in traditional medicine as vesicants or counterirritants and were also taken internally in some historical practices as a diuretic or aphrodisiac. These uses are now recognized as unsafe.

Toxicity and safety

The beetle’s defensive chemical, cantharidin, irritates tissues and can blister skin and mucous membranes. Modern sources describe ingestion as potentially severe or fatal and note that there is no known antidote.