PMD Bristle Nymph: Rethinking the CDC Collar With Pine Squirrel

Some of the best fly patterns don't come from trying to reinvent everything. They come from asking a simple question:

What happens if we change one material—and use the characteristics of that material to change how the fly fishes?

That idea is at the heart of the Moonlit PMD Bristle Nymph.

CDC has earned its place on modern nymph patterns for good reason. It's lightweight, incredibly mobile, and creates a soft, lively profile in the water. But CDC isn't the only way to create movement around the thorax of a nymph.

For the PMD Bristle Nymph, we're taking a different approach.

Instead of finishing the thorax with CDC, we're using Pine Squirrel dubbing followed by a sparse Pine Squirrel Zonker collar spun in a dubbing loop. The result is a collar with more mottling, a slightly more substantial silhouette, and a mixture of fine underfur and longer guard hairs that gives the fly its distinctive "Bristle" appearance.

Combine that with a slim segmented abdomen, subtle Micro Glint tail and legs, and a tungsten bead, and you have a PMD nymph designed to get down while maintaining plenty of movement and life.

CDC vs. Pine Squirrel: Different Materials, Different Results

This isn't about saying Pine Squirrel is "better" than CDC.

They're different materials—and that's exactly the point.

What CDC Does So Well

CDC has become popular on nymphs because of the incredible amount of movement you can create with very little material.

Those soft fibers respond to subtle changes in current and produce a delicate, flowing appearance around the thorax. Used sparingly, CDC adds movement without dramatically increasing the bulk of the fly.

That makes it especially effective when you want a soft, delicate collar.

CDC does have characteristics that can become limitations depending on what you're trying to accomplish.

The fibers are extremely soft. Once wet, they can collapse tightly against the body. CDC can also become affected by fish slime and repeated handling, changing how the material behaves until it's cleaned.

None of those characteristics make CDC a bad material. They simply create opportunities to ask whether another natural material might produce a different—and useful—effect.

Why Pine Squirrel?

Pine Squirrel gives us a very different fiber structure.

A Pine Squirrel Zonker contains both fine underfur and longer guard hairs. When we place a sparse amount of those fibers into a dubbing loop, we create a collar with variation already built into it.

The underfur provides softness and body.

The longer guard hairs provide movement and a broken, irregular silhouette.

And because natural squirrel isn't perfectly uniform, the dyed Bright Yellow Pine Squirrel retains beautiful variation and mottling throughout the fibers.

That's something I particularly wanted in this pattern.

Rather than creating a perfectly uniform yellow collar, the Pine Squirrel produces different shades and textures around the thorax. In the water, those longer fibers sweep backward and move with the current while maintaining more structure than an extremely soft CDC collar.

The result isn't a replacement that behaves exactly like CDC.

It's an alternative that intentionally behaves differently.

And that's what makes it interesting.

Why We Call It the "Bristle" Nymph

Look closely at the thorax and the name starts to make sense.

The Pine Squirrel dubbing creates a buggy foundation underneath the collar. Then the sparse Pine Squirrel Zonker fibers radiate around the thorax, creating the irregular, bristled profile that defines this family of patterns.

Mixed through that profile are the fine Semperfli Micro Glint legs.

The two materials work together to create different types of movement.

The Pine Squirrel provides the natural mottled fibers and soft-hackle-like movement, while the Micro Glint creates finer appendages with small flashes of light as the fly changes position in the current.

It's intentionally sparse.

We aren't trying to create a huge collar.

We want enough material to suggest legs, movement and life without overwhelming the slim profile of a PMD nymph.

Building a Slim, Segmented PMD Abdomen

The abdomen of this version of the PMD Bristle Nymph is deliberately simple.

Instead of building bulk with multiple materials, Primrose thread forms the body.

A fine strand of Bronze Holographic Tinsel is wrapped forward as the rib, creating pronounced segmentation and introducing just enough flash to provide another trigger without turning the entire fly into an attractor.

The abdomen is then coated with a thin layer of UV resin.

That serves two purposes.

First, it adds durability to the thread and tinsel body.

Second, it preserves the thin, sleek profile we're looking for in a mayfly nymph.

That sleek abdomen creates an important visual contrast with the fly's more irregular Pine Squirrel thorax.

Slim and segmented through the abdomen. Buggy and alive through the thorax.

Why a PMD Bristle Nymph?

Pale Morning Duns are one of the most important mayflies on many Western trout waters, and anglers understandably associate PMDs with dry-fly fishing.

But long before we see duns riding the surface, those insects are living below it.

That makes PMD nymphs important well before the first visible adults begin emerging.

As the hatch approaches, trout can become increasingly keyed into the nymphal stage. Those nymphs begin becoming more active and available in the water column as they prepare to emerge.

That's exactly where a pattern like the PMD Bristle Nymph fits.

We're giving the trout several characteristics to recognize:

• A slim mayfly-nymph profile
• Clearly defined abdominal segmentation
• PMD-oriented coloration
• Fine tail and leg fibers
• A buggy thorax
• Natural movement from Pine Squirrel
• Small amounts of flash
• A tungsten bead to help control depth

It isn't meant to be an exact anatomical reproduction of a PMD nymph.

It's designed to combine recognition with triggers.

When and Where to Fish the PMD Bristle Nymph

One of the great things about a PMD nymph is that you don't have to wait until you see adult PMDs to start fishing one.

If you know PMDs are present and you're approaching the hatch window, start underneath the surface.

Early in the day, the Bristle Nymph can be fished deeper as part of a nymph rig. The Moonlit Slotted Tungsten Metallic Coffee bead helps get the fly down, and you can upsize the bead when you need a faster descent.

As you begin seeing increased insect activity or trout feeding higher in the water column, adjust your depth accordingly.

The pattern can be particularly useful:

Before a PMD hatch when nymphs are becoming increasingly active.

During the early stages of emergence when trout are feeding below the surface before committing to adults.

In riffles and broken water where the Pine Squirrel collar and Micro Glint can move continuously in changing currents.

Along seams and transitions where drifting nymphs are concentrated.

In deeper runs when paired with the appropriate bead size to reach feeding trout.

And don't assume the fly stops being useful just because you start seeing adults.

If trout aren't consistently taking duns from the surface, there may still be substantial feeding happening underneath them.

Adjust the Bead to Adjust the Fly

We're tying the PMD Bristle Nymph on the Moonlit Premium TOGATTA ML501 in sizes 14–18 and pairing it with Moonlit Slotted Tungsten beads from approximately 3.5mm down to 2.5mm.

That gives you some flexibility.

Want the fly to descend quickly into a deeper run?

Upsize the bead.

Fishing shallower water or trying to keep the fly higher as the hatch develops?

Use a smaller bead.

Rather than thinking of bead size simply as part of the recipe, think of it as another way to control where the pattern fishes in the water column.

Watch the PMD Bristle Nymph Tying Tutorial

Follow along as we tie the PMD Bristle Nymph step-by-step and take a closer look at creating the Micro Glint legs, building the slim segmented abdomen, and using Pine Squirrel Zonker in a dubbing loop to create the Bristle collar.

PMD Bristle Nymph Materials List

Hook: Moonlit Premium TOGATTA ML501 — Sizes 14–18

Bead: Moonlit Slotted Tungsten Metallic Coffee — Sizes 3.5–2.5mm
Upsize the bead when you want a faster descent.

Thread / Body: Semperfli Classic Waxed 12/0 — Primrose

Tail / Legs: Semperfli Micro Glint — Brown

Ribbing: Semperfli 1/69" Holographic Tinsel — Bronze

Thorax: Moonlit Pine Squirrel Dubbing — Golden Olive

Collar: Moonlit Pine Squirrel Zonker — Bright Yellow

Tie the PMD Bristle Nymph

Want to tie the pattern without searching for every material individually?

We've put together the PMD Bristle Nymph Fly Tying Kit with everything you need for the pattern together in one place.

👉 [GET THE PMD BRISTLE NYMPH FLY TYING KIT]([INSERT KIT URL])

A few simple clicks and you'll have the materials ready to follow along with the tutorial and start tying your own PMD Bristle Nymphs.

A Different Kind of Movement

The goal of the PMD Bristle Nymph wasn't to prove that Pine Squirrel should replace CDC.

CDC is an outstanding fly-tying material, and there are times when its incredibly soft movement is exactly what we want.

The Bristle Nymph asks a different question:

What if we want more mottling, slightly more structure, and a different style of movement around the thorax?

That's where Pine Squirrel shines.

Its combination of soft underfur and longer guard hairs creates a natural, irregular collar that moves while maintaining the bristled profile that gives this pattern its identity.

Add the subtle movement and flash of Micro Glint, a thin segmented abdomen, and enough tungsten to put the fly where the trout are feeding, and you've got a PMD nymph designed to do one thing:

Get into the drift and look alive.

That's the Moonlit PMD Bristle Nymph.

Adventure Starts at the Vise.