bee killer

from The Century Dictionary.

• noun A kind of robber-fly, Trupanea apivora, a dipterous insect of the family Asilidœ, which attacks honey-bees on the wing and kills them.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun swift predatory fly having a strong body like a bee with the proboscis hardened for sucking juices of other insects captured on the wing