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 specimen seems to be morphologically identical to the darker specimens of its species, but it's a very distinctly different color. I'm guessing this is a gender difference, just as I've guessed for the similar E. subvaria nymphs.
This mayfly was collected from unknown in Wisconsin on February 5th, 2004 and added to Troutnut.com by Troutnut on January 25th, 2006.