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.
These adults are probably C. ferrugineus.
This mayfly was collected from the Flathead River-lower in Montana on August 13th, 2009 and added to Troutnut.com by Bnewell on June 27th, 2011.