Originally Posted by bear 007
My best guess is Ephemerella invaria
(female), one of about 4 or 5 eastern mayflies commonly known as Sulphurs
... time is right for them. Best hatch of the year in my old neck of the woods (SE PA).
If you tie, Google Tups Indispensable
and swing it under the hatch if you have trouble getting them to take your floating dun imitation.
Beautiful brookie pic's by the way. I agree with yonder, that second pic is magazine worthy.