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.
Creno on Nov 15, 2008November 15th, 2008, 8:14 am EST
While the photo is not as good as the previous (the wing venation/coloration is not in focus) I don't believe it is ocellifera as as my specimens of ocellifera are generally paler and with less wing coloration than the other two likely species (postica and semifasciata). I would not feel comfortable using just size and color to separate these species. I think you need to take a good look at the private parts to be sure.
There is an excellent source for this family:
Wiggins, G.B. 1998. The caddisfly family Phryganeidae (Trichoptera. University of Toronto Press. 306pp.