The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.
This is a small rather plain brownish mayfly with the middle abdominal segments black edged above in both male and female. Head above and upper division of the compound eyes brown, lower division black.
Thorax brownish, lighter on the sides. Legs whitish, a little tinged with amber on the femora. Wings of the male whitish hyaline; of the female tinged with light amber and with darker veins. Their costal cross veins are lacking except in the stigmatic area where they are few and simple.
Abdomen brown above, darkened across the ends of the middle segments so as to appear cross-banded; paler beneath. There are brown rings on the joinings of a few of the basal segments of the tails. The long joint of the forceps of the male is very slightly swollen at one-third its length and but little tapered beyond. The third joint is half as long as the second. The U-shaped cleft between the penes is somewhat widened downward and a little narrowed at the extreme outer end by the short hyaline lobes at the orifice (see fig. 133). Brown apices, obliquely truncate ending externally in a short tooth. Reflexed spur much longer than the middle cleft. Tip flattened, subclavate in outline, widened toward the free end. Lobes of the tenth sternite elongate triangular, separated by a rather narrow V-shaped cleft and rounded on the tips.