SeasonalityAdults can be collected from late June through late mid August in the southern parts of its range, but only in July in the northern parts (Teskey 1990; McElligott and Lewis, 1996b).
IdentificationFemales are 8-10 mm in length and predominantly black. On the head, the frons is slightly higher than its basal width, and the frontal callus, ocellar prominence, antennae, clypeus, and gena are black, and glossy to some degree; the clypeus has a median pruinose (powdery) stripe that extends to the oral margin; the palpi are brown (Teskey 1990). The thorax is dark with yellow hairs and indistinct submedian scutal stripes; the pleural stripes are grey pruinose; the lags are black; the wings have a strong crossband but one which does not reach the hind margin, and there is a prominent spur on wing vein R4 (Teskey 1990). The abdomen is mostly black, with lateral yellow patches on tergites 1 or 2 or both; tergites 2-7 have narrow grey posterior margins; the sternites are mostly black (Teskey 1990).
The males are similar except even darker, with more abundant black hair with reduced grey pruinosity on the thorax and less yellow on the abdominal tergites (Teskey 1990).
The wing pattern and dark coloration are unique.
Larvae are cylindrical, elongate, fusiform (spindle-shaped), creamy-white, and 14-16 mm long; the respiratory siphon lacks a stigmatal spine; the presence of more than 35 acute spines on tergum 7 separate it from other Chrysops larvae (Teskey 1969).