Mayfly Species Drunella flavilinea (Flavs)

A species of the fuscata group (now a synonym of Drunella walkeri); very close to E. coloradensis (now a synonym of Drunella coloradensis. The imago is distinguished from the latter species by the pale venation, and rather sharp constriction of the second joint of the forceps, near the apex.

Head and thorax deep ruddy brown. Femur and tibia of fore leg deep blackish brown; tarsi dull whitish. Tibia once and a half as long as the femur, and slightly shorter than the tarsus. Middle and hind legs are dull yellowish; a reddish brown apical patch on each femur on the inner side. Wings hyaline, venation pale. Abdominal tergites deep ruddy brown; sternites more reddish than the dorsal surface. A pale yellowish line along the pleural fold, which tends to extend upward at the edge of each segment, especially on the posterior ones. Tails blackish at the base, paler toward the tips. Second joint of the forceps with a rather sharp constriction near the apex; the tip bent inward (see fig. 153).

Nymph without frontal horns or a frontal shelf (see fig. 151 d). Occipital tubercles present, but no thoracic spines. Anterior margin of the fore femur with teeth or spines. Dorsal abdominal spines present on 2-9; very small on 9; somewhat shorter than in coloradensis (now a synonym of Drunella coloradensis). Tibial ‘thumb’ shorter than in coloradensis; fore tibia more slender; middle and hind legs stouter. General color variable, ranging from light to dark brown; pale specimens appear distinctly mottled. Femora with three pale indistinct areas; tibiae with distinct pale bands at each end; tarsi banded in the middle. Tails pale; narrow blackish bands beyond the middle and at the tips.