from
The Collaborative International Dictionary of English v.0.48
Gadfly \Gad"fly`\ (g[a^]d"fl[imac]`), n.; pl. {Gadflies}. [Gad +
fly.] (Zool.)
Any dipterous insect of the genus {Oestrus}, and allied
genera of botflies.
[1913 Webster]
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}.
[1913 Webster]
{Gadfly petrel} (Zool.), one of several small petrels of the
genus {Oestrelata}.
[1913 Webster]
from
The Collaborative International Dictionary of English v.0.48
oestrus \oes"trus\, n. [L., a gadfly; also, frenzy, fr. Gr. ?
gadfly; hence, sting, fury, insane desire, frenzy.]
1. (Zool.) A genus of gadflies. The species which deposits
its larvae in the nasal cavities of sheep is {oestrus
ovis}.
[1913 Webster]
2. A vehement desire.
[1913 Webster]
3. Specifically: (Physiol.) The periodical sexual impulse of
animals; the period during which female animals are most
receptive to males; heat; rut.
[1913 Webster +PJC]