The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
In 26 records from GBIF, adults of this species have mostly been collected during June (54%), July (15%), May (15%), and August (8%).
Time of day: Dusk
Current speed: Fast
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.
A species of the jejuna-undulata group, having no lateral spine basally on penes; small apical spines present on each division of penes.
Head and thorax deep brown; thoracic sternum paler, rather ochreous brown. Legs ochreous brown; femora “‘broadly shaded in their central portion with deeper brown, especially noticeable on the forelegs’” (McD.). Wings hyaline; a slight brownish tinge at base. Venation strong, blackish. Abdominal tergites deep brown; sternites paler, ochreous brown. Forceps and tails dark brown. Penes with no lateral basal spines on outer margin; apices “broader and much less outcurved” (McD.) than in the allied Rhithrogena jejuna, each division bearing several small apical spines (see fig. 101).
Distinguished from R. jejuna and Rhithrogena undulata by the small apical spines on penes, and by the fact that the penes are barely or not at all outcurved at tips.