Western March Browns
.............................Fly Fishing Yellowstone National Park
05/23/08

Western March Browns - (Rhithrogena sp) -Duns and Spinners

Duns:
Normally, at least on other streams in the West, the duns are the most important stage
to imitate. The time that they remain on the surface of the water depends upon the
temperature. The colder the day, the longer they tend to drift before flying away. These
mayflies are usually a hook size 14 to 16.

Presentation:
In streams with fast moving, rough water, where these mayflies are typically found, fish
the dry fly using an upstream presentation along the seams of pocket water and the
edges of the runs. Leaders should be about eight foot long with a two-foot size 4X
tippet. In the moderately moving water of some of the smooth flowing meadow sections
of the streams, you may need to use a down and across stream presentation, a longer
leader and smaller tippet size.

Spinners:
In some cases, the spinners are the most important phase of the Rhithrogena species,
but this depends on a lot of factors, mainly the weather and species, or time of year the
spinner fall occurs. The reason is that the duns hatch off and on throughout a long
period of time but the spinner fall concentrates the mayflies and it occurs in a much
shorter period of time. Calm evenings sometimes produce excellent spinner action. The
females usually lay their eggs over the riffles and runs of the stream but the trout tend
to eat them in areas of the streams where they collect.

Presentation:
When the spinner fall starts, upstream presentations made in the calmer areas of
pocket water and at the tail end of riffles and runs will usually work best. Slower moving
smooth water may require a down and across presentation using longer leaders and
smaller tippets. At some point the spent spinners will collect in the eddies, pockets and
other similar slow water areas below the runs and riffles. Spent imitations will produce if
presented in these areas. The down and across presentation usually works best for this.
Coming Up Next:
Western March Browns - (Rhithrogena sp) - Fly Pattern Colors

Copyright 2008 James