Spanish fly; Cantárida

Slender metallic emerald-green beetle in the family Meloidae, Coleoptera, ca. 20 mm. long. Spanish fly and cantharides refer to dried insects of this species, and related preparations used for supposed aphrodisiac effects. Poisonous when taken internally at large doses can be deathly. The perceived aphrodisiac properties of L. vesicatoria and its dried cantharides preparations are a result of its toxicology, specifically, irritant effects it has upon the body's genitourinary tract. Preparations from L. vesicatoria and other species have been the sources from which a chemical compound called cantharidin has been isolated, which is largely responsible for the pharmacologic activities described.
It is believed that king Fernando "the catholic" died due to excessive intake of Spanish fly when trying to get a heir for the Aragon crown