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.
I collected a female dun on the same day that probably belongs to the same species as this spinner. It keys pretty clearly to Epeorus pleuralis among the species given in the key in Taxonomy of Epeorus Frisoni (burks) And a Key to New England Species Of Epeorus.
This mayfly was collected from Enfield Creek in Treman Park in New York on May 15th, 2007 and added to Troutnut.com by Troutnut on May 18th, 2007.