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.
Entoman on Jul 10, 2013July 10th, 2013, 11:23 pm EDT
Looks like bilineata to me too, Eric. Spieth documented both the unique tergal markings and the black coloration in his '41 paper. The variability in this genus never ceases to amaze me.
"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