Pale Evening Duns
.............................Fly Fishing Yellowstone National Park

Pale Evening Duns Emergers:
The Pale Evening Duns emerge in the summer and early fall depending on the
particular location. Hatches at very high elevations can come earlier than those at the
lower elevations because the water starts cooling down earlier as a general rule.
Hatches normally occur in the afternoons if the weather is cool and evenings if it is hot.
Most of the time the weather will be cool, otherwise the water would not be but it is
possible for cold weather to reduce the water temps enough for them to hatch and then
turn back warm.
The nymphs migrate from the fast water to the slower parts of the stream just prior to
hatching.  In pocket water this may be only a couple of feet or yards, so don't take this
to mean they move several hundred yards because they don't. This usually move to
shallow water near the banks of small pockets where the water is calmer than the
surrounding faster water.
They normally hatch in water between 50-55 degrees F. but remember this is not a
early summer hatch when the water warms up to that temperature. They start to hatch
when the water cools down to that temperature. In Yellowstone this can be anywhere
from mid August to October depending primarily on the altitude but also the varying

Emerger imitations can be presented on the swing from the faster water to the shallow
water near the banks. You want to allow the fly to reach the surface at the end of the
drift. An up and across presentation works best for this.
We have two types of emerger patterns for most all mayflies that hatch in the water
including this one. One is a CDC winged version on a curved hook designed to float in
the surface skim and the other is a trailing shuck emerger imitating the nymphal shuck
still stuck to the tail of the newly emerged dun. This one is also designed to float in the
surface skim. Both can be presented on the swing in the same manner.

Coming Up Next:
Pale Evening Dun

Copyright 2008 James Marsh