The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
In 22 records from GBIF, adults of this species have been collected during June (68%), May (23%), and July (9%).
In 6 records from GBIF, this species has been collected at elevations ranging from 938 to 2161 ft, with an average (median) of 1901 ft.
"They emerged from their shucks with such speed that I was usually left with an empty shuck and the subimago with which I was already familiar. I began to think that catching the trout was easier than catching the nymphs that the trout were catching."
Time of day: Dusk
Substrate: Silt and detritus, sometimes fine gravel and sand
Environmental tolerance: Low tolerance for pollution and warm water
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.
Abdomen largely creamy white, no black pencilings; contrasted strongly with wings, which appear largely blackish.
Head red-brown; frontal portion of median carina blackish; basal joints of antenna whitish, filament pale red-brown; heavy black rings at bases of ocelli. Pronotum light red-brown, with darker lateral areas; posterior margin whitish at median line. Remainder of thorax very dark red-brown; large pale areas on pleura, anterior to wing roots, at bases of legs, between wing roots and legs. Fore legs dark reddish brown; a white area apically on dorsal edge of coxa; apical half of tibia and all joinings deeper brown; tarsus slightly paler than femur and tibia. Claws marked with whitish. Middle and hind coxae and trochanters red-brown; femora yellowish with faint tinge of red; tibiae and tarsi whitish; apical margin of femur red-brown, claws largely pale purplish brown (Eaton says, blackish spot at apex of tibia, tarsus sometimes light red-brown).
Wing so heavily blotched with dark purplish or blackish brown as to appear largely blackish. Longitudinal veins in anterior half of fore wing dark red-brown, elsewhere yellowish amber. Cross veins blackish or dark red-brown. Majority of cross veins in fore wing widely margined with dark purplish brown, forming many large blotches of same color, arranged much as in Ephemera simulans, but more extensive and with additional dark areas. Bullar stripe may extend to cubital vein; very wide at fork of posterior branch of radial sector, covering 5 to 6 veins within this fork. A partial second stripe on some wings, at first apical blotch beyond bulla; in others, this and next blotch beyond it may be partially fused; several other small blotches near margin of wing, from apex to cubitus; elongate blotches between branches of cubitus; other dark areas larger than in Ephemera simulans, cross veins more widely margined. In hind wing, majority of cross veins rather widely margined, those of anal region only narrowly dark-edged. A large dark blotch near base of subcostal space; another in the two spaces just below it, at basal and second fork of radial sector; below the latter, cross veins very widely margined for three spaces; smaller blotches nearer outer margin, which is widely tinged with pale reddish brown.
Abdominal segments 2-8 wholly pale yellowish white, except for reddish pleural streak on 8; median apical area of tergite 1 also pale, remainder of 1 red-brown; segment 10 largely bright red-brown, two yellow lateral streaks on tergite; lateral reddish-brown stripes on sternite 9, and pleural margin same color. Forceps reddish-brown, second joint paler; third joint relatively longer than in others of this genus. Penes distinct structurally from other species in our fauna (fig. 82). Tails olive to pale reddish brown, joinings blackish brown.
The very pale abdomen, wholly lacking the usual blackish pencilings, combined with the very dark-appearing wings, distinguishes this from other species.