robber fly

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various predatory flies of the family Asilidae, characteristically having long, bristly legs.

Century Dictionary and Cyclopedia

1. n. Any dipterous insect of the family Asilidæ. They are large swift flies with strong proboscis, and prey upon other insects. They are also called hornet-flies and hawk-flies. The term robber-fly is taken direct from the German raubfliege. See cuts under Asilus, hawk-fly, and Promachus.

GNU Webster's 1913

1. n. (Zoöl.) Same as Hornet fly, under Hornet.

WordNet 3.0

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