- A beetle (Lytta, / 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.