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'm not sure of the species of this female spinner, and unfortunately I never found the associated males or duns to aid in identification. The egg-laying flight and fall of fairly large clouds of these females caused good rises of choosy trout for a week or so around early July on a large, cold spring creek in the northwoods. There is a distinctive stripe down the female's back, identical to that on this specimen collected a month later.
This mayfly was collected from the Bois Brule River in Wisconsin on July 1st, 2005 and added to Troutnut.com by Troutnut on April 22nd, 2006.