.......................  ......Fly Fishing Yellowstone National Park

07/09/09

Fly Fishing Yellowstone - Small Western Green Drakes (Flavs)

The Drunella favilineas are called Small Western Green Drakes because that is
really what they are - smaller Green Drakes. There are differences in the
Western Green Drakes and the Small Western Green Drakes as far as the
scientist are concerned, but not much as far as anglers should be concerned
with. The nymphs, duns and spinners are different sizes than those of the
Western Green Drakes. The Flavs are normally one or two hook sizes smaller.

The nymphs are fairly easy to distinguish but the duns are not. That fact makes
little difference to anglers. What does make a difference is the different sizes
and time of the day and time f the year they hatch. There is little difference in
their behavior. In some ways the Flavs may be more important to anglers than
the larger more famous green drake, the
Drunella grandis. They are usually
more wide spread, plentiful and they hatch over a longer period of time than the
big green drakes.

There are two other species of Flavs, the
spinifera and the coloradensis, that
are also Small Western Green Drakes. They are included in this same group of
mayflies. I am not certain if all three species exist in the park but it makes no
difference as far as anglers are concerned. You would need a microscope to
determine the difference. The Flavs hatch well after the Green Drakes hatch on
any one stream but it is possible to have a hatch of Flavs occurring before the
Green Drakes hatch on different streams in the park due to the difference in
drainage and elevation of the streams.









Copyright 2009 James Marsh