The Collaborative International Dictionary of English v.0.48:

Bombylious \Bom*byl"i*ous\ (b[o^]m*b[i^]l"[i^]*[u^]s), a. [L.
   bombylius a bumblebee, Gr. bombylio`s.]
   Buzzing, like a bumblebee; as, the bombylious noise of the
   horse fly. [Obs.] --Derham.
   [1913 Webster]