The Pale Morning Dun (PMD)

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Date: 01/01/2025

Most anglers don't have to spend too much time out here before they here about the Pale Morning Dun, a.k.a. PMD. These beautiful little pale yellow Mayflies hatch almost every morning through June and July depending on the river, stream or lake. The higher the elivation, the longer into the summer they last. This is one of the many Mayflies that are available to Trout every stage of life. Since they are a swimming nymph, they can be found by fish all the time, I guess they have never grasped the concept of hide and seek. The nymphs get extra active just before they start their emergence. As the name suggests, Pale Morning Duns hatch in the morning, usually sometimes as early as 8 or 9, maybe as late as 11. Once the emergence starts, a person can instantly see the insects on the water. Little Sailboats floating down. If you pay a little closer attention you'll not only see the Sailboats floating down but alot of bugs that just look kind of half done. Maybe a wing or two will be all curled up or there seems to be a chunk of something coming off of it's abdomen. A huge percentage of PMD's hatch as Cripples. Even if they are completely healthy, PMD's spend a lot of time on the water before they fully emerge and dry their wings. Because of this, fish have a ton of time to key in on them. I do think of Trout as a predator, picking off the weak and sick. The adults that make it, are called Duns, they usually fly off into the trees to fully mature, mate and return to the river later that evening as Spinners to lay eggs, die, and once again have the opportunity to feed a Trout. The males turn a light to deep rust color called a Rusty Spinner. The females remain pale yellow.

Here are the three main stages mostly available to the fish. Emerging Cripple, Dun and Rusty Spinner.

A person can start seeing PMD's as early as opening day on the Firehole in late May, early to mid June on the Madison, Missouri and Henry's Fork, and maybe even as late as early August in places like Slough Creek and Lamar River. Basically, no matter where you are at early to mid Summer, a person should have a few PMD's in the fly box.