Spotted Sedge - Pupae
.............................Fly Fishing Yellowstone National Park
04/21/08

Pupae:
The Spotted Sedge (Hydropsyche species) pupae are eaten by trout during the hatch
on a regular basis. It is the easiest time for the trout to consume the pupae because
they drift in the current for a relatively long time before reaching the surface where they
emerge as adults.
When it approaches the time of year for the particular species of
Hydropsyche to hatch,
the larvae will go in their shelters and seal the openings. There they will proceed to spin
a cocoon to use to pupate. It takes about two or three weeks for them to form the pupa.
At the time the hatch begins, the pupa will eat its way out by chewing a hole in the
cocoon. It will then proceed to swim to the surface to hatch. This is the time that the
trout can easily pick off the pupae. 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. The bottom line to this is that these caddisflies are
eaten from the time they emerge from their cocoon until they fly away to streamside
foliage far more than any other time of their life.
The emerging process usually starts late in the afternoons 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 Pupa:
You want to start fishing an imitation of the pupa late in the afternoon. These caddisflies
emerge from the riffles and runs of pocket water, and from the moderate to fast moving
water of smooth flowing streams. If you are catching trout on a 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 an imitation of the adult.
Some anglers fish the pupa imitation of the Spotted Sedge using a strike indicator.
Although this method will catch some trout, I think you would probably be better off
fishing without an indicator. If you are fishing smooth water, then I suggest you use a
down and across presentation. You may need to weight the fly to help get it down. You
should also mend the line a time or two to help get the fly down. When the fly gets
almost directly downstream of your position, just stop the downstream drift by stopping
the swing of the rod. The current will bring the fly to the surface where you want to
leave it 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.

Coming Up Next:
Spotted Sedges - Hydropsyche species - Adults

Copyright 2008 James