It is possible that the same Mayfly species can have size variations through the season. Also, many species can look very, very similar. Detail of the hindwing can be most helpful (not easy to photograph). The forewing veins, eye and face, leg lengths, and tail details usually need to be examined to ID, the male forceps is often the only way to be sure, some females cannot be ID'd unless collected with the male. This image is most likely Baetidae based on the two tails and turbinate eyes, exceptions seem to be the rule for Mayflies.

john and jane, if i hadn't noticed this flying and landing, i'd have walked right by it considering it to be no more than another dust mote... i pushed my camera to its limits getting this photo... ted edwards

It's always interesting when you look at the pictures, you get a idea of how big the animal is you are looking at. Then you glance at the size given and do a double take! Wait a minute! Did we have this one pegged wrong. Thanks for including the size. We would never have guessed.

Baetidae have some species with a body length of only 3mm. Other Mayfly families have some very small species as well. This one is a male (turbinate eyes) and most likely an imago.

we had a bit of damage about here from last years wild fires and i was off line for a while, my thanks to you all for id help.... i really appreciate your efforts on my behalf... sorry it took me sooooo long to get back to you, ted