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

06/09/09

Fly Fishing Yellowstone - Spotted Sedge Pupae

Probably more Spotted Sedge (Hydropsyche species) Pupae are eaten by trout
during the hatch than any other stage of life of this caddisfly. It is very easy for
the trout to eat them because the pupae drift in the current for a relatively long
time before they reach the surface to emerge into adults.

The larvae build shelters to reside in when they are not feeding out on the end
of their silk line at their nets. To explain what goes on just before the hatch,
consider that when it gets close to the time of year for
Hydropsyche caddis to
hatch, the larvae will go in their shelters and seal the openings. They will spin a
cocoon to pupate. The pupae are formed within a couple of weeks or so. When
hatch begins, the pupae eat their way out of the cocoon by chewing a hole in it.
As soon as they escape the cocoon, they swim to the surface to hatch. This
triggers the trout to begin feeding. They have no trouble eating the helpless
pupae drifting in the current trying to reach the surface to hatch.

These caddisflies emerge in moderate to fast moving water. From the time they
escape their cocoon and begin their accent to the surface they are carried
downstream by the current. The pupae are in this helpless situation for some
time. When they reach the surface of the water, the pupal shuck splits and the
emerged adult caddisfly quickly flies away. The trout can also easily pick them
off during the time they are emerging from their pupa shuck in the surface skim.
These caddisflies are eaten from the time they emerge from their cocoon until
they fly away to streamside vegetation far more than any other time of their life.

The emerging process usually starts late in the afternoon and continues until
well into the night. The egg laying activity of the adult females from previous
hatches will actually start during the time other caddisflies are emerging.

Imitating the Pupae:
Start fishing an imitation of the pupa late in the afternoon. The Spotted Sedge
caddisflies emerge from the riffles and runs of pocket water. They can also be
found emerging from the moderate to fast moving water of smooth flowing
streams. If you are catching trout on our pupa imitation, then you should
continue using it until you start seeing trout eating the egg layers. This is usually
very late in the afternoon, well after the sun has set. At that time you may prefer
to change to our imitation of the adult.

You can fish the "Perfect Fly" Spotted Sedge Pupa using a strike indicator. I
think you would probably be better off fishing without an indicator. If you are
fishing smooth water, use a down and across presentation. Mend the line a time
or two to help get the fly down. You may need to add weight above the fly to
help get it down. When the fly gets almost directly downstream of your position,
stop the downstream drift by stopping the rod. The current will bring the fly to
the surface. Leave it there for a few seconds.  
We have had excellent success in many of the streams in Yellowstone Park
using the down and across method. This method has worked very well in both
the smooth water sections and the runs and riffles of the Madison, Firehole and
Yellowstone Rivers























This is our
"Perfect Fly" Spotted Sedge Pupae Fly



Copyright 2009 James Marsh