|....................... .................... ...Fly Fishing Yellowstone National Park
New KISS Bug Series - Part 23
Pale Morning Dun
The Pale Morning Dun nymphs are found in the slow to moderate flowing waters of the streams they
inhabit. They are not a fast water nymphs, they are crawler nymphs and crawler nymphs don't do very well
dealing with fast water. The Pale Morning Duns, usually just called PMDs, have a one-year life cycle.
The PMD nymphs can swim although not very well. Like many other nymphs, their exact coloration is
somewhat a product of the stream they live in and the color of the nymphs will vary slightly depending upon
I would think trout eat these nymphs on a regular basis since they are regularly exposed to them, or at
least they don't tend to stay underneath rocks like the clinger nymphs do. They do stay down between the
cobble and gravel on the bottom of the stream. In streams like the Madison, Gibbons and Firehole Rivers,
where there's lots of vegetation, they can probably avoid being eaten to some extent by hiding in the
plants. There's certainly no shortage of these nymphs in the streams of Yellowstone National Park, so there
are plenty of them that don't get eaten by the trout.
Let me straighten out something that may cause some confusion. Although the nymphs are found in slow to
moderate flowing water, don't overlook the fact that this can be in slower, calmer areas of streams that
consist mainly of fast, pocket water. You will find plenty of them in the fast sections of the Yellowstone
River, Soda Butte Creek and many other streams with sections of fast water. You will find them in the
slower sections of water in pockets along the banks and in pockets behind large rocks and boulders. They
are also found at the ends of long runs and riffles and the slower moving water on the inside of the river
bends. Most streams have as many or more of these nymphs as any mayfly nymph that inhibits the
stream, so fishing an imitation of the PMD nymph is always a pretty good fly choice.
I know most everyone, including me, wants to fish a dry fly every chance they get. There are occasions that
if you want to catch trout, you better get the fly down near the bottom where the trout feed most of the time.
You can fish an imitation of the nymph on the bottom anytime during the season prior to the beginning of
the long hatch period That means from the time the season opens until the PMD hatches have ended on
The hatches normally start mid-morning. During those days a hatch is occurring, you can start out with a
nymph imitation and continue to fish it up until the hatch begins. The nymphs swim to the surface and hatch
in the skim.
In pocket water, prior to a hatch, I would fish the nymph imitation in the current seams and the through the
long moderately flowing runs and riffles. Weight it down with and keep it on the bottom as much as
possible. Use a very short, up and across cast and follow the nymph downstream holding the rod tip high.
Continue until the nymph is down and across and then make another cast a couple of feet upstream of the
previous one. You will have to approach the areas you are fishing carefully to avoid spooking the trout
when you are making this short of a cast.
In smooth water you will need to make a much longer, up and across presentation and keep the nymph on
the bottom by weighting the tippet a few inches above the fly. You will probably need to frequently mend
the line. Smooth water in some rivers can be deceptive. The current is usually very strong even though the
water is smooth. There may be a lot of vegetation that your fly will hang on unless you carefully select the
areas to drift your nymph through.
It's also difficult to keep a drag free drift in the swirling currents caused by vegetation in streams like the
Madison, Gibbons and Firehole Rivers.. I watch the end of my fly line to detect strikes but you may prefer to
use a small strike indicator. Fish the nymph until it is in the down and across position before making
|Pale Morning Dun:
Availability to trout:
Type of water:
Duration of hatch period:
Ephemerella infrequens/ E. inermis
Moderate to slow - smooth and broken surface