Note the long occipital bristles which help characterize this genus. Abdominal segment 6 of the female is incorporated into the terminal genital structure, making the ovipositor appear especially long. Compare with Machimus, Philonicus, and Efferia.
Mystax black or white (usually black in males). Front and middle femora are yellow, each with a black stripe on the upper side. All tibiae yellow.
Size: 12-18 mm
Range: Eastern U.S. and Canada
FL Range: Panhandle and north Florida
Season: February – October throughout range
FL Season: February 28 – June 1
Mystax bright yellow. All femora entirely black. All tibiae yellow.
Size: 12-19 mm
Range: Eastern U.S. and Canada south to Georgia
Season: May – September
Hine, J. S. (1909). Robberflies of the genus Asilus. Annals of the Entomological Society of America, 2(2), 136-170.