Copyright 2014 James Marsh
Hatches and Trout Flies for the Lewis River- Yellowstone National
The hatches on the Lewis River are usually not very prolific but they are varied and plentiful at

Blue-winged Olives may still be hatching when the water first clears.  There are several species
including the
baetis. They hatch twice a year but the fall hatch is the most important one. It
takes place in September and can last until the first week of October depending on the

The PMD, or Pale Morning Dun, is the most consistent hatches that take place on the Lewis
River. They are usually hatching when the water first clears and last  through July.

Spotted Sedges are very plentiful, especially in the meadow sections or smooth water sections
below the Grand Loop Road.. They start hatching around the first part of July and last through
August. Little Sister Caddisflies hatch during the same time period. Green Sedges are very
plentiful in the fast water sections. Species of these caddisflies hatch from about the middle of
July all the way into October.  Little Short-Horned Sedges hatch during the first part of July.
There are a few Long--horned Sedge hatches.

Gray Drakes hatch from about the first of July until the first week of August This hatch occurs
in the smooth meadow section of the stream. There are also some Brown Drakes in the smooth
water section. They hatch from about the first of July and last a couple of weeks.

Salmonflies are present in the fast water sections. They start hatching about the first week of
July and last for a couple of weeks depending on the water and weather.  Golden Stoneflies will
start hatching about the same time. They will be present in good quantities in the fast water
sections of the stream. Yellow Sallies, or Little Yellow Stoneflies, are also plentiful. They start
hatching the middle of July and last until the first week in August.

You will find Yellow Quills, or the
Eperous species, hatching from about the middle of July
through the first part of August. Western March Browns start hatching about the same time and
last through the middle of August. Both of these mayflies prefer the faster sections of the
stream such as the riffles and runs.

Grasshoppers, ants and beetles are very plentiful in the meadow section of the Lewis River.
The high grass along the banks of this section provide the perfect habitat for them. Imitations
of these insect will work during late July, August, September..

Don't overlook the possibility of flying ants. We have seen two huge flying ant falls occur on the
Lewis River during the month of August.

Our "Perfect Flies" have proven to be more effective than any of the generic or attractor flies
you could use on the Lewis River. We have specific imitations of everything that hatches and in
all stages of life that the trout eat them in. If you haven't already tried them, we certainly hope
you will.
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Lewis River, YNP