Tying the Pale Morning Dun: Four Patterns for the Hatch That Humbles Everyone

The Pale Morning Dun is not a difficult hatch to find. From late May through September, on nearly every trout stream worth naming between the Rockies and the Cascades, Ephemerella inermis and its close relative E. excrucians crawl off the bottom, drift toward the surface, and attempt to shed their nymphal shucks and fly away. Millions of them. Every day. For months.

The difficulty is that trout know exactly what's happening, and they've developed opinions about it.

A PMD hatch on the Henry's Fork or the Missouri River or DePuy's Spring Creek is one of the great spectacles in fly fishing, dozens of fish rising steadily in a single run, pale yellow mayflies drifting on the surface in a lazy flotilla, the whole scene radiating calm abundance. And then you tie on a PMD dry fly, make a perfect cast, get a perfect drift, and the fish rises to the natural six inches to the left of your fly and ignores yours completely. You change flies. Same result. You go smaller. Same result. You go to 7X tippet and a different pattern and a different angle, and the fish eats another natural and lets your fly drift past like it's invisible.

This is the PMD experience. The hatch is easy to find. The fish are easy to locate. And they are extraordinarily difficult to fool, not because PMDs are rare or complicated, but because they're so common that trout have seen every imitation in every fly shop in Montana. The fish have been educated by a thousand anglers who all tied on the same parachute pattern, and now they know the difference.

The solution isn't one fly. It's understanding which stage of the PMD emergence the trout are actually eating, and carrying a pattern that matches that specific moment in the insect's life cycle. A PMD dun sitting perfectly upright on the surface is the last thing most trout want during a heavy hatch, they want the vulnerable ones. The emergers stuck in their shucks. The cripples that can't get their wings free. The nymphs ascending through the water column. The trout are sorting through a buffet line, and they're picking the easy meals.

Here are four patterns, one for each stage of the PMD emergence, that solve the problems this hatch creates.

The Insect, What You're Actually Matching

Before you tie anything, you need to know what you're imitating. Doug Swisher and Carl Richards coined the common name "Pale Morning Dun" in their 1971 book Selective Trout, which revolutionized how anglers think about matching hatches. The name stuck because it describes the insect perfectly: pale yellow body, dun-colored wings, and a tendency to emerge in the late morning hours.

Two species share the name. Ephemerella inermis is the more common, the larger bug, sizes 14-16, found on virtually every significant trout stream in the West. Ephemerella excrucians is smaller (sizes 16-20) and hatches later in the season, often overlapping with inermis. On any given day in July, you might have both species on the water simultaneously in different sizes. When trout are refusing your #16 PMD, try an #18, the fish may be keyed on excrucians while you're matching inermis.

The color varies more than most anglers expect. "Pale morning dun" suggests one color, but the duns range from creamy yellow to olive to pale green, with subtle pink or rusty undertones depending on the species, the time of season, and the specific water. On the Missouri River, they tend toward a warm yellow. On the Henry's Fork, the olive cast is more prominent. Early-season PMDs run larger and more yellow; late-season bugs are smaller and often greener. Carrying a single PMD color covers most situations, but carrying two, a pale yellow and an olive, covers them all.

The emergence behavior is what matters most for pattern selection. PMD nymphs are crawlers, they live on the streambed and are poor swimmers. When it's time to hatch, they release from the bottom and drift helplessly through the water column toward the surface. This drift takes time. The nymphs are exposed and vulnerable for several feet of distance before they reach the film. Once at the surface, they struggle to break through, the shuck splits along the back, the wings emerge, and the dun attempts to pull itself free and fly. Many fail. Crippled and stillborn PMDs, insects that got halfway out of their shuck and couldn't finish, are common, sometimes representing 30-40% of the bugs on the water. Trout know this, and they target the failures.

Pattern 1: The Sparkle Dun, Solving the Emerger Problem

The Sparkle Dun exists because Craig Mathews couldn't get the trout on the Henry's Fork to eat a Comparadun during PMD hatches. Mathews, who ran a fly shop in West Yellowstone, had been fishing Al Caucci and Bob Nastasi's Comparadun, the no-hackle deer hair wing pattern from their 1975 book Comparahatch, with good results on less pressured water. But on the Henry's Fork Railroad Ranch, where the trout see more PMD imitations per season than fish on any other river in the West, the Comparadun wasn't enough.

In the early 1980s, Mathews and his partner John Juracek started experimenting. They wanted the Comparadun's flush-in-the-film profile, no hackle dimples, no unnatural silhouette, but they needed something more. What they added was a trailing shuck: a sparse tail of Z-Lon or Antron yarn that trailed behind the fly and sank slightly below the surface, imitating the nymphal case that a mayfly leaves behind during emergence. The trailing shuck told the trout that this bug was still hatching, still vulnerable, still stuck, still an easy meal.

They called it the Sparkle Dun, and it became the most important PMD pattern in Western fly fishing.

PMD Sparkle Dun Recipe

No hackle. No legs. No parachute post. The wing provides all the flotation, and the trailing shuck sinks just below the film. Apply floatant to the deer hair wing and dubbed body, but not the shuck, you want the shuck to break through the surface like a real nymphal casing.

When to fish it: During the active hatch, when duns are on the water and fish are rising steadily. The Sparkle Dun is the first pattern to reach for during a PMD emergence, it covers both the emerger and the dun stage simultaneously. If trout are eating with confident, head-and-tail rises, this fly will take fish.

Pattern 2: The Quigley Cripple, Solving the Stuck-Shuck Problem

Bob Quigley was fishing a Humpy on California's Fall River in 1978 when a trout chewed the wing off his fly. He kept fishing it, and caught more fish with the mangled pattern than he had with the intact one. The wing, bent forward over the eye of the hook, apparently looked more like a struggling insect than a pristine one. Quigley went home and tied a fly around that accident.

The result was the Quigley Cripple, and with it, Quigley coined the term "cripple" to describe mayflies that get stuck partway out of their shucks. Before Quigley, fly tiers either imitated perfect duns or generic emergers. Quigley identified the specific moment between those stages, the bug with its wings half-out, its shuck still attached, its body half in and half out of the film, and built a pattern around it.

The Quigley Cripple rides with its abdomen hanging below the surface and its thorax and wing above it, supported by a few turns of hackle and a forward-facing wing of deer or elk hair. The posture is unmistakable from below, half insect, half shuck, entirely vulnerable.

PMD Quigley Cripple Recipe

The key to the Cripple is the forward-facing wing. Unlike a standard dry fly wing that sweeps back, the elk hair extends forward over the hook eye and is trimmed flush with the thorax at the back. The hackle supports the front of the fly on the surface while the pheasant tail abdomen and Z-Lon shuck hang below the film. The whole posture screams "stuck."

When to fish it: When trout are making soft, sipping rises rather than confident head-and-tail takes. Sipping rises mean the fish are eating insects trapped in the film, cripples and stillborns that can't fly away. The Quigley Cripple is the deadliest PMD pattern during the middle and tail end of a hatch, when the water is littered with failed emergers.

Pattern 3: The Barr Emerger, Solving the Subsurface Problem

John Barr developed his emerger pattern in the 1970s while fishing the PMD hatches on Nelson's Spring Creek near Livingston, Montana. Barr noticed that during heavy PMD emergences, the most consistent feeding happened not on the surface but just below it, in the top few inches of the water column where nymphs were shedding their shucks and transitioning into duns.

The Barr Emerger solves this by fishing in the film and just below it. The abdomen imitates the nymphal shuck (olive-brown dubbing), the thorax imitates the emerging adult (grey muskrat or beaver dubbing), and the wingcase of dark spade hackle fibers represents the partially emerged wing.

PMD Barr Emerger Recipe

When to fish it: Before and during the early phase of the hatch, when trout are feeding subsurface. Watch for fish that rise without breaking the surface, their backs bulge the water and you see a flash of flank, but no head or mouth appears. Those fish are eating emergers an inch below the film.

Pattern 4: The Pheasant Tail Nymph, Solving the Pre-Hatch Problem

You don't always need a specialized PMD nymph. Frank Sawyer's Pheasant Tail Nymph, tied in #16-18 with a bead, is the best PMD nymph imitation available, and it's a pattern you already carry. The natural pheasant tail fibers match the rusty-brown coloration of PMD nymphs perfectly, and the slim profile mimics the crawler body shape.

Before the hatch begins, in the hour or two before the first duns appear on the surface, PMD nymphs become active on the streambed and begin drifting in the current. This "behavioral drift" is the feeding opportunity that most anglers miss.

Fish the Pheasant Tail dead-drift near the bottom with split shot and an indicator, or on a tight-line Euro rig. As the hatch progresses and you start seeing the first risers, switch to the Barr Emerger or the Sparkle Dun.

Variations, Matching the Hatch to the Water

PMDs are not one-size-fits-all. The size and color shift across the season and from river to river:

• Early season (late May–June): Larger bugs, #14-16, pale yellow to cream. Tie your Sparkle Duns and Cripples in #16 with a warm yellow dubbing.
• Mid season (July): Peak hatch density. Both species present. Size #16-18. Color tends toward a slightly warmer yellow, sometimes with an orange tint to the abdomen.
• Late season (August–September): Smaller bugs, #18-20, shifting toward olive-green. The olive PMD Sparkle Dun in #18 is a different fly from the yellow #16 you fished in June.
• Overcast days: Expect denser hatches, later in the day. The fish feed with more confidence in cloud cover.
• Sunny, warm days: Sparser, quicker hatches. Cripples and emergers make up a higher percentage, exactly when the Quigley Cripple earns its keep.

Where to Fish PMDs

Henry's Fork, Idaho, The Railroad Ranch section is the PMD's spiritual home. Craig Mathews developed the Sparkle Dun specifically for this water. The PMD hatch runs from mid-June through August in sizes 16-18.

Missouri River, Montana, Below Holter Dam, the Missouri's tailwater produces one of the heaviest PMD hatches in the West. The long, slow flats below Craig, Montana fill with rising fish from late June through July.

Yellowstone Country, The Firehole River inside the park, the spring creeks of Paradise Valley (DePuy's and Armstrong's), and the upper Yellowstone all have significant PMD hatches from June through August.

Green River, Utah, Section A below Flaming Gorge Dam has a PMD hatch from late June through August in sizes 16-18.

The Driftless Area, The spring creeks of southwest Wisconsin, northeast Iowa, and southeast Minnesota hold PMD populations that hatch from June through July. A simple Comparadun in #16 pale yellow does the job here.

How to Tie Them, Video Tutorials

Fly Tying for Beginners: A Pale Morning Dun with Jim Misiura

Clear, slow instruction covering the fundamentals of proportioning, dubbing, and hackle wrapping for a standard PMD dry fly.

Pale Morning Dun Sparkle Dun Fly Tying Video

A focused walkthrough of the deer hair fan wing and Z-Lon trailing shuck, the PMD pattern that matters most.

Tying a Pale Morning Dun Emerger with Davie McPhail

McPhail's emerger tutorial covers the subsurface patterns that fool trout feeding below the film during PMD hatches.

Tips From the Vise and the Water

Match the shuck color to the nymph, not the dun. The trailing shuck on your Sparkle Dun should be brownish-amber, the color of the nymphal exoskeleton, not the pale yellow of the adult.

Thin bodies, always. PMDs are slim insects. Overdubbing is the most common tying mistake. Use a dubbing loop or touch-dubbing technique and build the thinnest body your thread will allow.

Fish the individual, not the pod. During a PMD hatch with twenty fish rising in a run, pick one rising trout. Read its rise form. Present your fly three feet upstream and let the drift do the work.

Read the rise form. A confident head-and-tail rise means duns, try the Sparkle Dun. A soft sip means emergers or cripples, try the Quigley Cripple. A subsurface bulge means ascending nymphs, go subsurface with the Pheasant Tail or Barr Emerger.

Use longer leaders. PMD fishing on flat water demands 12 to 16 feet of leader tapered to 5X, 6X, or 7X.

Time the transition. The best window is those first 20 minutes when the duns are appearing but the trout haven't yet seen enough flies to get picky.

Carry BWOs too. Blue Winged Olives overlap with PMDs in June and again in September. If nothing is working, look more carefully, you may be seeing olive BWOs mixed in.

Build Your PMD Box

For a week on PMD water, tie:

• Sparkle Dun PMD: 8 flies in #16, 8 in #18 (pale yellow dubbing, amber Z-Lon shuck)
• Sparkle Dun PMD olive: 4 flies in #18 (olive dubbing, for late-season or mixed hatches)
• Quigley Cripple PMD: 6 flies in #16, 6 in #18 (pheasant tail abdomen, yellow thorax)
• Barr Emerger PMD: 6 flies in #18, 4 in #20 (pale yellow abdomen, grey thorax)
• Beadhead Pheasant Tail: 6 flies in #16, 6 in #18 (you should already have these)

That's 54 flies, three or four evenings at the vise. The Sparkle Duns will get the most use, the Quigley Cripples will catch the pickiest fish, and the Barr Emergers will save you when nothing on the surface works.