.......................  ....................  ...Fly Fishing Yellowstone National Park
New KISS Bug Series - Part 52

Small Western Green Drakes (Flavs)

As You can see from the below image the "Flav" dun looks much like the "Western Green Drake". The only
real difference is the size of the two mayflies or actually two or three different species of each one. The two
different species of 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
differences in their hatch times and stream habitat.

The Small Western Green Drake common name 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 a
"Flav". 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 even 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 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 drainages and elevations.
Copyright 2012 James Marsh
Sm. West. Green Drakes