asilus

from The Century Dictionary.

• noun A genus of two-winged flies, of the family Asilidæ, popularly known as hornet-flies, robber-flies, or hawk-flies.
• noun In ornithology: [lowercase] An old name (Gesner, 1555, to Brisson, 1760) of the willow-warbler, Phylloscopus trochilus.
• noun A genus of such warblers.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) A genus of large and voracious two-winged flies, including the bee killer and robber fly.