Slender delicate flies, 3.0-13.0 mm long. Eye in both sexes usually divided transversely into an upper region with larger ommatidia and a lower region with smaller ommatidia. Legs long; hindleg stouter than others. Wing membrane with net-like pattern of folds; M2 completely detached. Coloration usually uniform, mostly dull testaceous or gray without bright colors or conspicuous markings, occasionally with indistinct bands or areas of darker shades on scutum and abdominal tergites.