Hatches begin in early spring while the air temperature is still very cool. There have been reports of great dry fly fishing as early as mid April, in heavy snow flurries with an air temp. of 38 degrees. Epeorus nymphs are clingers preferring fast moving riffles and require clean, pollution free water. Biologist use these nymphs as an indicator of a streams water quality. Hatch activity begins during the warmest time of the day, usually mid afternoon. Epeorus pluralis nymphs shed their husk under water and the duns swim to the surface providing a good oportunity to fish wet fly patterns such as Quill Gordon wets and Lead Winged Coachman. Spinner activity usually starts as the air temp. climbs into the 50's, again during the warmest time of the day. Look for a mixture of duns and spinners during this period. This early in the season spinners may appear in the air while the sun is over the water, but may follow the suns warmth away from the river eventually falling elsewhere.