Spanish fly noun2 •The beetle Lytta vesicatoria.Spanish flies applied to the skin produce blisters (vesication, with inflammation and even sloughing). — 2003 •A supposed aphrodisiac extracted from the blister beetle Lytta vesicatoria; cantharidin, the active ingredient, a vesicant used as a defence by L. vesicatoria and other blister beetles.Ingestion of Spanish fly causes burning in the throat and sloughing of the upper gastrointestinal tract. — 2010 formsSpanish flies
