Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
In Baumann's Stoneflies of the Rocky Mountains, this specimen keys to Sweltsa fidelis, but the number of species in that key is fairly small and it might not be accurate.
This stonefly was collected from the Madison River in Montana on June 30th, 2019 and added to Troutnut.com by Troutnut on July 17th, 2019.