\Gad"fly`\, n.; pl. {Gadflies}. [Gad + fly.] (Zo["o]l.)
Any dipterous insect of the genus {Oestrus}, and allied
genera of botflies.
Note: The sheep gadfly ({Oestrus ovis}) deposits its young in
      the nostrils of sheep, and the larv[ae] develop in the
      frontal sinuses. The common species which infests
      cattle ({Hypoderma bovis}) deposits its eggs upon or in
      the skin where the larv[ae] or bots live and produce
      sores called wormels. The gadflies of the horse produce
      the intestinal parasites called bots. See {Botfly}, and
      {Bots}. The true horseflies are often erroneously
      called gadflies, and the true gadflies are sometimes
      incorrectly called breeze flies.
{Gadfly petrel} (Zo["o]l.), one of several small petrels of
   the genus {Oestrelata}.