Now until late October, the slowly rising light colored mayflies will rise from the edges of the quieter water of streams. A pleasant certainty on many streams is the late morning & again late afternoon hatch that sputters out near evening time.  As with all these hatches, there abounds comprehensive info with scientific names re the PMD’s, PED’s even Pale Afternoon Duns. Have at it if that terminology gene is clanging away demanding more info. Check out Trout Nut or similar bodies of work by Hughes and Hafele. In the meantime, in a more practical application tie or buy the necessary svelt brown crawler nymphs and cream-tan colored  emergers, adults and spinners.