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 have pretty good eyes, but i can't really tell if they have a pair hanging down...
Anyway...Generally the males of a particular mayfly species are smaller than the females...
As to color...The variation we think we see could be diet in a particular stream, the color changing after the bug actually frees itself from the nymphal shuck, or we are simply misidentifying the bug we have in our hands.