Fishing the Montana PMD Hatch (Pending)

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Date: 08/03/2024

The pale morning dun (PMD), scientific genus ephemerella, a very important western mayfly, is a very fun hatch to fish and can vary from easy to incredibly difficult and technical. When it is good, it can be the most fun hatch to fish by miles, but the same can be said when it is technical. This hatch can be extremely difficult because of the life stages of PMD’s and also how picky trout can be when they are on this hatch.

The life stages of PMD’s that trout can look for include the nymph, emerger, dun, and finally the spinner. The nymph stage is the longest period of life for the PMD and lasts until they emerge. Emerging PMD’s struggle with breaking the surface of the water and are very susceptible to trout in this stage. Emergers are often taken just below the surface or even partially in the neuston layer. Upon emerging, ephemerella reaches its adult or dun stage. These are commonly seen as yellow bodied flies that look very similar to a sailboat floating on the water’s surface. PMD’s can also have problems getting both wings clear of their wing case while emerging resulting in a “cripple”. Duns proceed to fly off the water and mate. After mating the females lay their eggs then become spinners and males immediately become spent flies that are commonly known as spinners. Spinners lay flat on the surface of the water with wings extended perpendicular to the fly’s body.

PMD’s in Montana tend to begin hatching mid-late June and can continue until mid-late July. Catching the hatch when it initially starts can make for the best fishing as trout almost always will take a juicy PMD over a caddis fly. When you see fish rising early on in the hatch you can often get them on spinners, emergers, duns, or short leashed nymphs. This hatch tends to get much more difficult later on in the season. When this is the case, an angler will need to match the exact life stage, size, and pattern that the fish is on. Making things more challenging, these hatches can go full cycle, nymph to spinner, in a matter of hours and you can see duns, cripples, and spinners all on the water and have no idea which the fish are munching.

Nymphing with PMD patterns is usually really good in the morning before a PMD hatch or in the afternoon after the hatch has concluded. My favorite PMD nymphs include the PMD Bubbleback and the Electric Yellow Micro May. When you see fish rising and see fins and swirls but do not see mouths, fishing a cripple or an emerger in the film is the way to go. The best patterns for this stage of the hatch are the Last Chance PMD cripple or the CDC Biot Emerger. Usually when fish are on duns you can see the small yellow sail boat disappear into the white mouth of a rising fish. The best dun patterns for this rising style are the PMD Thorax and the PMD Parachute QG. Lastly, when fish are on spinners, my personal favorite, you will see a very brief nose break the surface followed by a small dimple on the water. The best fly, hands down, is the Hi-Vis Rusty Spinner. Trout do not tend to move much laterally when they have a good stream of PMD’s so a good cast directly over the fish is essential.

PMD season has arrived in Montana. We have heard good reports from the Missouri and have been sighting pale morning duns on the Lower Madison. Swing by the shop to restock on PMD patterns and good luck this ephemerella season!