Mayfly Species Dannella simplex (Blue-Winged Olives)

A small, dark colored species; penes ending in two broad lobes, with minute papillae at the apices; nymph somewhat flattened, hairy, without occipital, thoracic or dorsal abdominal spines; gills on segments 4-7.

Eyes deep brown; head deep blackish brown. Thorax deep blackish brown; lateral margin of the mesonotum, and the dorsal transverse suture, pale brown. Mesosternum blackish brown in the central portion, light brown laterally between the middle and hind legs. Fore leg blackish; middle and hind legs dull yellowish brown; femur and tibia of hind leg subequal, tarsus two-thirds of the tibia. Wings hyaline; longitudinal veins brownish; cross veins apparent only in the stigmatic area. Abdominal tergites blackish brown, almost unicolorous, the lateral margins slightly paler; tergites 8 and 9 shaded with paler brown. Dull yellowish brown ventrally; sternite 9 shaded with blackish brown, as are also the forceps. Penes curve upward; each ends in a broad lobe, with a slight ventral heart-shaped depression just basad of the lobes; minute papillae are borne near the apex of each lobe (see fig. 157). Tails dull smoky.

The nymph is rather broad and flat and very hairy. Pale olivaceous to deep brown in color, shaded variously with dark brown on the abdominal tergites. No occipital nor thoracic tubercles, nor dorsal abdominal spines are present. Genae considerably produced laterally. Femora rather chunky, the fore femora bearing a series of long hairs transversely across the middle. Femora with two dark bands; tibiae banded apically, tarsi with a median dark band. No denticles on the claws. Lateral extensions of the abdomen rather well developed, and bearing postero-lateral spines on segments 4-9. Gills borne on segments 4-7 only, that on segment 4 being rather strongly operculate. Markings of the tergites consist of interrupted dark submedian and lateral streaks which may broaden and coalesce. Sternites pale; unmarked, or with lateral rows of dark dashes. Tails pale, the joinings faintly ringed; with weak whorls of spinules and some fine fringing hairs apically.