The Spanish fly is an emerald-green beetle Lytta vesicatoria, (from Greek lytta = rage and Latin vesica = blister) in the family Meloidae . It is still sometimes referred to as Cantharis vesicatoria, but the genus Cantharis is in an unrelated family, Cantharidae. It is 15 mm to 22 mm long and 5 mm to 8 mm wide, and lives on plants in the families Caprifoliaceae and Oleaceae.

Medical use

The beetle contains up to 1% cantharidin. The powder made from dried and crushed beetle has been used as an aphrodisiac, under the mistaken impression that the urinary irritation created was sexual arousal. Its medical use dates back to descriptions from Hippocrates.

A similar powder from Myalabris beetles (also in the Meloidae ), called "vuka-vuka" (vuka = wake up), is known in Zimbabwe.