Until fairly recently the Hybotid Flies were considered a subfamily within the family Empididae. In its current status the family Hybotidae includes subfamilies Hybotinae, Tachydromiinae, and Ocydromiinae.
Harold Oldroyd, in his classic Natural History of Flies (1964), said of this group, "These flies run about swiftly, and seize their prey with their legs, often having the femur and tibia of at least one pair spiny, and shaped to close upon each other like the jaws of a wrench. There is a rich fauna of small insects, mites, and spiders running about on the surface of vegetation, and these insect thugs have a good time of it."
A scan of the thumbnails below will show that some groups, such as genera Hybos and Syneches, are strikingly hump-backed, a trait most easily seen in profile.
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