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

06/06/09

Fly Fishing Yellowstone - Spotted Sedge

Looks like Yellowstone is in for some lousy weather for a few days. Rain and
snow is in the forecast until next Tuesday. Temperatures should be in the forties
for the highs and twenties to thirties during the evenings. This will keep the
runoff at a creeping pace.

The other caddisfly that is and will be hatching for quite sometimes now on the
Firehole River, Lower Gibbons and Madison Rivers is the Spotted Sedge of
Hydrosyphe species. These caddisflies will be around for some time. They are
supposed to be the most plentiful caddisfly in the park but in the Firehole and
Madison Rivers, that is challenged this day in time by the White Millers I just
wrote about. They have increased in quantities for the past few years.

The spotted sedges are net-spinners. They don't build cases and that means
they are available for the trout to eat as larvae. They build a shelter type
covering that reside in but they hang out on the end of a silk string they produce
when they feed. They form tiny nets that catch their food by filtering it from the
water. These caddisflies exist in huge quantities and I suspect far more of them
are eaten as larvae and pupae than adults although trout definitely eat the adult
egg layers.

If you pick up a rock from the stream to look for these larvae, the net will
collapse and be very difficult to observe  If all other conditions are present, the
more algae there are in a stream, the more likely there are net spinning
caddisflies present. The Firehole River and Madison Rivers have a huge
amount of algae.

There are about seventy species in the Hydropsyche genus. Fortunately,
there is not much difference in the many species or certainly not enough
difference that the methods of imitating them or the imitation itself (fly) needs to  
be different for the various species.

Every stream in Yellowstone contains Spotted Sedges. Some of them have
huge populations of these insects. They live in the riffles and runs of the
streams. They must have current to survive.

Copyright 2009 James Marsh