Pale Morning Dun (PMD)
The Pale Morning Dun is considered by many anglers to be the most important mayfly
in the West. It certainly rivals the Blue-winged Olive species for that title. This is
primarily due to the fact that they emerge over such a long period of time and provide
fairly predictable hatches. These are species of the Ephemerella genus, often just
The infrequens species may start emerging as soon as the water temperature gets into
the low fifty degrees Fahrenheit level. This species can hatch for as long as a couple
of months on the same river.
The inermis species start emerging later on in the year, after the infrequens, depending
on the stream and can last as long as two months on the same stream. There are a
couple of other species that are not that prevalent. These two important species, the
inermis and the infrequens, are so similar that they cannot be distinguished without the
aid of a microscope. You can rest assured the trout can't tell the difference except that
they will be aware of the different hatch times.
Pale Morning Duns prefer streams with rooted vegetation but any of the streams with a
stable flow of water usually have consistent PMD hatches. This is certainly a mayfly that
you need to become familiar with and have imitations of if you plan on fishing just about
any stream in the western states included the Coastal region.
These mayflies can range from as large as a hook size 14 down to a size 18. We have
never seen any of the 14's so I doubt they exist to much extent. Our Perfect Fly imitations
comes in sizes 16 and 18 and we have imitations of all the stages of the Pale Morning
Duns life - nymphs, duns and spinners. We also have two versions of the emerging
nymphs. A regular emerger that's more like the nymph than a dun and an emerger with a
trailing shucki attached that's more like the dun than the nymph. Both versions work with
some anglers preferring the plain version and some the trailing shuck version.
If it's a cloudy overcast day, misting rain or snow, during the long hatch period of the Pale
Morning Duns, you can expect the hatch to last much longer than most mayfly hatches.
They seem to prefer adverse weather conditions. Imitations of the PMD are the American
Express flies. Don't leave home without them.
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