"Flavs" - Small Western Green Drakes
.............................Fly Fishing Yellowstone National Park
05/25/08

Flavs (Small Western Green Drakes) - (Drunella sp)












The Small Western Blue-winged Olives common names includes three species of
mayflies from the
Drunella genus that are common in the West.  The most common
species, the
favilinea, is usually just referred to as "Flavs". This is about as close a
many anglers ever get in using the Latin name of an insect. Whatever you call them,
these are important mayflies in Yellowstone National Park. In some ways they may be
more important to anglers than the larger more famous green drake, the
Drunella
grandis
. They are usually more wide spread, plentiful and hatch over a longer period of
time than the big green drakes.
There is are two other species, the
spinifera and the coloradensis, that are also smaller
Western Green Drakes that are included in this same group of mayflies.
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.

Coming Up Next:
Flavs - (Drunella flavilinea) - Nymphs and Emergers

Copyright 2008 James
You can see that the "Flav" dun does
look much like the "Western Green
Drake". The only real difference is the
size of the two species. The Western
Green Drakes are larger but only by a
hook size or two. The nymphs are fairly
easy to distinguish but the duns are
not. It makes little difference to anglers
except for hook size and some
differences in their behavior.