Pale Morning Dun

The Pale Morning Dun (PMD) defines summer trout fishing in the West. As the water warms in late June, these yellow-bodied mayflies (Ephemerella) take center stage. Unlike the BWO, PMDs prefer sunny to mixed-weather mornings and can hatch for hours. They are often the "main event" on famous rivers like the Henry's Fork, Madison, and Missouri.

PMDs prefer cold, clean water with rich aquatic vegetation. They are most abundant in spring creeks and tailwaters, but also frequent the slower riffles and runs of freestone rivers. They favor silty or gravelly bottoms where the crawlers can maneuver.

Unlike BWOs, PMDs are fair-weather friends, hatching reliably on sunny or partly cloudy mornings. The emergence is slow and deliberate; many nymphs get stuck in the surface film, making the 'cripple' stage a critical focus for anglers. Spinners return in the cool of the evening.

Seasonality Late June through August/September.

Tactics Fish the "Cripple" stage. Patterns like the Quigley Cripple or Sparkle Dun are often more productive than high-floating duns because PMDs struggle to escape their shuck.

Moderate sensitivity. PMDs decline in waters with heavy siltation or elevated temperatures. Their presence is a sign of good stream health.