|....................... .................... ...Fly Fishing Yellowstone National Park
New KISS Bug Series - Part 27
Spotted Sedges (Caddisflies)
The Spotted Sedges are the most plentiful caddisflies in the trout streams of the Western United States.
They also exist in the Mid-west and Eastern United States trout streams. The many different species hatch
off and on throughout most of the entire fishing season in Yellowstone National Park. If you don't have
anything else in the way of caddisfly imitations in your fly box, you better make certain you have Spotted
Sedges. They exist to some extent in every stream in the park and in most of them, they are very plentiful.
They will be present on some streams when the season opens including the Madison and Firehole Rivers.
The Spotted Sedges were considered to be the most plentiful caddisfly the Firehole and Madison Rivers
but in recent years that is being challenged by the White Millers. I'm not certain which group prevails there
but it seems the White Millers have been gradually increasing year by year.
The Spotted Sedges are net-spinners. They don't build cases and that means they are readily available for
the trout to eat as larvae. They build a shelter type covering they reside in but when feeding, they hang out
on the end of a silk line or string their body produces. They also build tiny nets that catch their food from
the current. The little nets work like filters.
If you pick up a rock from the stream to look for these larvae, the net will collapse and be very difficult to
observe They are very small, much less than the size of the tip end of your little finger. If all other
conditions are present, the more algae there is in a stream, the more likely net-spinning caddisflies are
present. The Firehole River and Madison Rivers not only warm faster than most of the streams in
Yellowstone National Park, they have a huge amount of algae.
There are about seventy species in the Hydropsyche genus. Fortunately, there's very, very little difference
in the many species and certainly not enough difference that the methods of imitating them, or the imitation
of fly itself.
Every stream in Yellowstone National Park contains Spotted Sedges. Some of them have huge populations
of these insects. They live in the riffles and runs of the streams but can't exist anywhere there's current.
They must have current to survive.
Availability to trout:
Type of water:
Duration of hatch period:
Moderate to slow - smooth and broken surface