PMD Hatch
"The Pale Morning Dun Hatch
produces fun, challanging fishing!"
By George Anderson

Here in Livingston, and across Montana we are blessed with a phenomenal hatch of a large, olive cast mayflies that everyone calls Pale Morning Duns. For trout hunters, the PMD hatch makes for some spectacular dry fly fishing. Various PMD hatches occur during the period from late June throughout July and often well into August on many of our streams.

This is THE hatch of the year on the famous spring creeks of Paradise Valley, like Armstrong’s, DePuy’s and Nelson’s. Anglers in the know book early to secure a space on these spring creeks during "prime time" of the PMD hatch, knowing that this will be some of the finest fishing – especially dry fly fishing – of the entire year.

This hatch occurs on most Montana streams, usually in July, but different species of the same basic insect make this perhaps the most important hatch of the season, especially on the flat-water streams like the spring creeks, the Firehole, Slough Creek, Soda Butte and the Lamar river in Yellowstone Park and also tailwaters like the Lower Madison and the Missouri.

The first PMD’s of the season to appear are the largest – the Ephemerella Infrequens, which are imitated with duns that average size 16 but often look as large as 14’s. Rene’ Harrop’s PMD No-Hackle in a size 16 with a big gray wing silhouette and pale olive body is a perfect imitation.

Harrop PMD No Hackle

Here on our spring creeks, we’ll see good hatches of Infrequens starting in mid-June. Early to mid-July produces some of the best dry fly fishing on these larger PMD’s. The Infrequens hatches seem to taper off at the end of July, but at the same time, another smaller version of the PMD appears, know as the Ephemerella Inermis and these hatches continue throughout July and well into August. The Inermis looks like a scaled down version of its larger brother, just one to two sizes smaller. A PMD imitation in size 18 is generally the best size but 20’s will often work even better on the well-educated trout of the spring creeks. Although you will periodically see some of the larger PMD’s throughout the summer, the majority of hatches in mid July throughout August will be the smaller Ephemerella Inermis.

Typically the PMD hatches start at 9-10 AM on most days and are heaviest for a period of 2-4 hours, bringing up lots of big fish. You’ll find big fish slurping them in everywhere, and it looks like it is going to be a piece of cake catching a ton of fish, but it is often not quite that easy! The challenge and the “game” that we all play is finding that exact fly that will fool these fish without hesitation.

Much of the time it looks to the un-initiated that the trout are taking high riding duns, but during the PMD hatches, I’ve found that fishing emergers, cripples and even emerging nymphs is usually the ticket to catching a lot of fish. The trout seem to recognize that the high riding duns can fly off the water at any given moment, so they pass them up, looking for duns that are struggling in the surface film, trying to free themselves from their nymphal shuck. When this is happening, two-tone emergers like the Dr. Barr PMD emerger, and Rene Harrop’s PMD CDC Captive Duns are deadly. The back half is brown, like the nymph, while the front half of these flies are a brighter pale olive or yellow/olive of the emerging mayfly.

Fish seem to realize that these struggling duns are easy prey, and they search them out relentlessly, often passing up 90% of the high riding duns. Good anglers score well with both nymphs like a Sawyer Pheasant Tail in size 16-18, or any of the good emerging PMD nymphs like our Olive Drake, a fly with a darker wing case that imitates the nymph splitting out of its shuck on the way to the surface.

As well as emergers, cripples and drowned duns in the surface film are easy prey during the PMD hatch. One of my most effective patterns, that I’ll go to when it seems nothing else will work is Rene Harrop’s simple short wing, Olive emerger. I grease this up and fish it right in the surface film, but you can also fish it sub-surface like an emerging nymph. Various cripple patterns can be deadly, like the Last Chance Cripple in 16’s and 18’s. I often fish an Olive spinner during the height of the hatch, as trout are looking for any duns that have not been able to upright themselves and are drifting helplessly in the surface film.

Sight fishing to nymphing fish in the spring creeks is extremely effective and a lot of fun since you can target the largest fish, and they are often not any tougher to get to take the fly than the smaller fish. The crystal clear water of the spring creeks allows an angler to observe feeding fish more closely, and the fun part of the game begins, changing patterns and trying to find that one fly that will consistently have big trout moving three to four feet to suck it in! Then the fun starts, while these strong 16-20 inch rainbows and browns cartwheel across the pool sometimes running hard and long enough to get you into your backing.

A bonus during the PMD hatches is getting to fish the spinner falls in the evenings. On most days when the hatch is heavy, look for these PMD spinner falls from 6-8 PM in the evenings, especially if it is relatively calm. All those duns you see in the grass in mid-day will be dancing in their mating flights and then falling spent on the water in the evening, making them the easiest of targets for big fish. A good spinner fall will bring up a lot of big fish, giving the dry fly enthusiast another couple of hours action that can be fast and furious.

This is the excitement of the PMD hatch, one that brings back anglers year after year to fish the Spring Creeks and other streams where the PMD’s abound.

Here in Livingston, during July and August, it is easy and fun to combine a day or more on the spring creeks with some float fishing on the Yellowstone River or perhaps the Madison, where the fishing is easy, and you can throw big attractor drys, hoppers and even streamers.

We (www.yellowstoneangler.com) book guided trips with many of the finest guides in our area that specialize in fishing these PMD hatches on the Spring Creeks. There is no better way to learn to catch fish under the challenging conditions like these PMD hatches provide than to hire one of these top guides for a day or more. You can often learn more in one day than you might on your own in five years!

Casting accuracy and timing the rise rhythm of an individual trout and anticipating where the trout will rise next is often the key to success, and this is where a good guide can really help. Once you learn to catch fish consistently during the height of the PMD hatch, you’ll be able to catch fish anywhere under difficult conditions.

Article written by George Anderson ©
www.yellowstoneangler.com