A Species of Robber Fly (family Asilidae): As described in the Kaufman Field Guide to Insects of North America, robber flies “are to other insects what falcons are to other birds: swift predators on the wing.” There are about 1,000 different species of robber flies in North America, many looking similar to the one in this photo. You’ll often spot a robber fly perched on a branch or rock, eating its most recent victim. Photo by Matt Schaefer on 8/2/18 near Stevensville, MT.