Spanish Fly, the emerald-green beetle Lytta vesicatoria (family Meloidae), sometimes also referred to as Cantharis vesicatoria. 15-22 mm long lives on plants in the families Caprifoliaceae and Oleaceae. The beetle contains up to 5% cantharidin which irritates animal tissues. The crushed powder of Spanish fly is of yellowish brown to brown-olive color with iridescent reflections, of disagreeable scent and bitter flavor. Since ancient times dried and mixed with food or drink supposed to work as an aphrodisiac. Wikipedia