The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
In 9 records from GBIF, adults of this species have been collected during June (44%), July (44%), and May (11%).
Time of day: Dusk
Current speed: Slow
Substrate: Firm silt
Environmental tolerance: Intolerant of warm water or pollution
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.
Wings heavily tinged with dark reddish brown; abdomen pale yellowish brown, dark markings few and inconspicuous; tips of penes narrow, recurved.
Head red-brown; carina, basal antennal joints and tip of filament paler. Eyes yellowish above; separated by space equal to about half diameter of one eye. Pronotum light red-brown; lateral margin narrowly darker; lateral stripes very narrow, indistinct. Mesothorax and metathorax deep reddish to blackish brown; faint yellowish markings along postero-lateral margin of mesonotum and on a small area anterior to scutellum. Creamy white markings on pleura below wing roots and around bases of legs. Ventral area of fore coxa pale reddish; upper part of coxa, trochanter and femur yellowish red; tibia pale red-brown; tarsus greyed lavender, the claws, tip of distal joint and bases of middle joints narrowly paler. Middle and hind legs yellowish; coxae red-brown; tarsi very faintly grey-tinged; tarsal joinings narrowly purplish grey. Wings heavily tinged with reddish or purplish brown, leaving hyaline areas only at base of each wing, and beyond disc and near apex of fore wing. Veins blackish; cross veins of both wings rather widely margined with dark red-brown, in dark areas. Outer margin of hind wing not darker than adjacent areas.
Abdomen pale yellowish brown; segment 1 light red-brown; sternites slightly paler than tergites. Pleural fold and posterior margins of all segments paler; tergites with very faint grey mid-dorsal line, narrow on basal ones, somewhat wider apically. Faint semi-opaque yellowish triangles based on posterior margins may be visible. A brownish line on each spiracular area. On each sternite, an oblique brownish sub-median streak from anterior margin on each side, and two dark dots near center, one on each side. No other dark markings. Tails light purplish brown; joinings darker, each preceded by a narrow paler ring. Forceps base, basal forceps joint and penes pale reddish; remainder of forceps greyed lavender. Penes distinctive, the distal third of each narrowed and recurved. Basal forceps joint short and stout, second joint relatively long and incurved apically; distal joints normally well developed (see fig. 84). The distinctive recurved tips of the penes, and the brown-tinged wings reminiscent of Ephemera guttulata distinguish this from other species of the genus. Nymph shown in fig. 47.