The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
This female spinner was deceased when photographed, so the posture is unnatural, but it was a substantial hatch and clearly worth imitating (with wet flies to imitate the sunken ovipositing females) so I went ahead with the photos.
It was collected in association with a male spinner.
This mayfly was collected from Silver Creek in Idaho on September 4th, 2020 and added to Troutnut.com by Troutnut on September 18th, 2020.