Eristalis \E*ris"ta*lis\, n. [NL.]

(Zo["o]l.) A genus of dipterous insects whose young (called rat-tailed larv[ae]) are remarkable for their long tapering tail, which spiracles at the tip, and for their ability to live in very impure and salt waters; -- also called drone fly.

Source: Webster's Revised Unabridged Dictionary (1913)