What is "cantharis"

Blister \Blis"ter\, n. [OE.; akin to OD. bluyster, fr. the same root as blast, bladder, blow. See Blow to eject wind.]

1. A vesicle of the skin, containing watery matter or serum, whether occasioned by a burn or other injury, or by a vesicatory; a collection of serous fluid causing a bladderlike elevation of the cuticle.

   And painful blisters swelled my tender hands.
   --Grainger.

2. Any elevation made by the separation of the film or skin, as on plants; or by the swelling of the substance at the surface, as on steel.

3. A vesicatory; a plaster of Spanish flies, or other matter, applied to raise a blister.
   --Dunglison.

   Blister beetle, a beetle used to raise blisters, esp. the Lytta vesicatoria (or Cantharis vesicatoria), called Cantharis or Spanish fly by druggists. See Cantharis.

   Blister fly, a blister beetle.

   Blister plaster, a plaster designed to raise a blister; -- usually made of Spanish flies.

   Blister steel, crude steel formed from wrought iron by cementation; -- so called because of its blistered surface. Called also blistered steel.

   Blood blister. See under Blood.

Cantharis \Can"tha*ris\ (k[a^]n"th[.a]*r[i^]s), n.; pl. Cantharides (k[a^]n*th[a^]r"[i^]*d[=e]z). [L., a kind of beetle, esp. the Spanish fly, Gr. kanqari`s.] (Zo["o]l.) A beetle ( Lytta vesicatoria, syn. Cantharis vesicatoria), having 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.

n. (singular of cantharides English)

Cantharis is a large genus of soldier beetles in the family Cantharidae with narrow and soft elytra.

The poisonous Spanish fly is superficially similar and is associated with the scientific name Cantharis vesicatoria. It is also sometimes called "cantharis" in the vernacular, but it is actually unrelated to Cantharis and is not a member of the Cantharidae at all. It was classified there erroneously until Johan Christian Fabricius corrected its name in his Systema entomologiae in 1775. He reclassified the Spanish fly in the new genus Lytta as Lytta vesicatioria. It belongs to the family Meloidae.