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.
This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
Entoman on Mar 11, 2012March 11th, 2012, 4:14 am EDT
The head markings better match up with A. carolinensis (pronounced unbroken W, thick tapering occipital band). Another clue is the femora maculation. A. abnormis usually has either dark brown legs without obvious maculation or longitudinal dark stripes as opposed to the pale bands or blotches evidenced on this specimen. While a dark dorsal habitus is usually associated with abnormis, it is not a very dependable character. The other common species (lycorias) has head and leg markings that can look quite similar, but it has anal gills and usually a pale center with dark margins on the terga.
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman