Can"tha*ris (?), n.; pl. Cantharides (#). [L., a kind of beetle, esp. the Spanish fly, Gr. kanqari`s.] (Zoöl.) A beetle (Lytta, or Cantharis, vesicatoria), havin1g an elongated cylindrical body of a brilliant green color, and a nauseous odor; the blister fly or blister beetle, of the apothecary; -- also called Spanish fly. Many other species of Lytta, used for the same purpose, take the same name. See Blister beetle, under Blister. The plural form in usually applied to the dried insects used in medicine.

• the Spanish fly, Lytta vesicatoria, taken to have aphrodisiac properties
       *1964: Speaking her name, it was as if he spake pure cantharides. ‘Quick,' she panted. ‘There is time before they are all about. Again.' — Anthony Burgess, Nothing Like The Sun
       *1992: It's lucky that Carol had taken the precaution of obtaining some cantharides; without them the evening might have been a dead loss. — Will Self, Cock And Bull