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.
This specimen keys to the Epeorus albertae group of species. Of the five species in that group, the two known in Washington state are Epeorus albertae and Epeorus dulciana. Of the two, albertae has been collected in vastly more locations in Washington than dulciana, suggesting it is far more common. On that basis alone I'm tentatively putting this nymph in albertae, with the large caveat that there's no real information to rule out dulciana.
Patello-tibial suture: A particular suture in the tibia of an insect's leg, the presence or absence of which is sometimes used in the identification of Baetidae mayflies.
These other words reference the same concept: patella-tibial suture, patello-tibial sutures, patella-tibial sutures.
The letters "pts" designate the patello-tibial suture in zoomed-in view (D) of the middle leg (C) of a Turkish Baetidae mayfly. Licensed via Creative Commons and WikiMedia from the following publication: Sroka P, Godunko RJ, Rutschmann S, Angeli KB, Salles FF, Gattolliat J-L (2019) A new species of Bungona in Turkey (Ephemeroptera, Baetidae): an unexpected biogeographic pattern within a pantropical complex of mayflies. Zoosystematics and Evolution 95(1): 1-13.
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