Montana’s Classic Stonefly Bench: The Improved Bird’s Stone and the Kaufmann Stimulator
Series: Montana’s Classic Stonefly Bench — Article 2
Every generation of western fly tiers inherits something from the one that came before it and then has the nerve to improve it.
Cal Bird built his stonefly on the principle that three clumps of elk hair bound in sequence told a more honest story about Pteronarcys californica than anything else available. He was right. Six decades of Montana trout confirmed it. But a fly built in the 1960s on a San Francisco bench eventually meets the Henry’s Fork, and the Henry’s Fork has opinions.
Mike Lawson spent enough time on that river to understand that Bird’s original, for all its genius, had room for refinement. The Henry’s Fork is not the Madison. It does not reward flies that approximate. It rewards flies that commit. Lawson tightened the profile, improved the durability, and produced the Improved Bird’s Stone — a pattern that kept everything Bird understood about stonefly silhouette and fixed what fast, pressured water revealed about its weaknesses.
Then Randall Kaufmann did something different entirely.
Kaufmann didn’t refine the Bird’s Stone. He took the elk hair logic that Barnes and Bird had proven and built something new from it — a fly so versatile that it matches salmonflies in size 4, golden stoneflies in size 8, and caddis in size 14 depending on what color you put on the hook. He called it the Stimulator and it became the most widely used stonefly dry fly in the American West almost immediately, which is either a testament to the pattern or an indication that western fly fishers are always looking for one fly that does everything.
It is a testament to the pattern.
This is Article 2 of Montana’s Classic Stonefly Bench. If you haven’t read Article 1 covering the Improved Sofa Pillow and the original Bird’s Stonefly, start there — it’s where this series and this hatch both begin.
Table of Contents
What Changed and Reason It Mattered
The original Bird’s Stonefly was built for utility. Three elk hair segments, palmered hackle, flat down wing — it worked because it was honest about the shape of the bug and fast to produce in volume. What it wasn’t built for was the kind of sustained scrutiny a heavily pressured fishery like the Henry’s Fork applies to every fly that comes over a fish.
On the Henry’s Fork, trout have seen everything. They have opinions about elk hair diameter, about hackle fiber length, about whether the wing profile matches the natural’s tent-shaped resting position. This is not hyperbole. Anyone who has fished Last Chance in July and watched a twenty-inch rainbow refuse a fly that caught twelve fish on the Madison two weeks earlier understands exactly what the Henry’s Fork does to patterns that are merely good enough.
The Improved Bird’s Stone addressed durability and profile simultaneously. The Stimulator addressed versatility — a fly that could move with the angler from river to river, hatch to hatch, without requiring a complete box change.
Both belong on your bench. They solve different problems.
How to Tie the Improved Bird’s Stone — Mike Lawson
Why This Fly Exists
Mike Lawson refined the Bird’s Stonefly at Last Chance on the Henry’s Fork because the original, fished hard on demanding water, revealed structural weaknesses that casual fishing never exposes. The segmented elk hair abdomen loosened under repeated casting stress. The wing profile, acceptable on broken water, didn’t hold up under the low-angle scrutiny of spring creek fish feeding in slow, clear currents. Lawson tightened the construction at every binding point, reinforced the abdomen with a dubbed underbody, and improved the wing by selecting finer, more consistently textured elk hair that produced a cleaner downwing silhouette. The result is a harder-wearing, more precise version of Bird’s original that fishes everywhere the original does and performs better where the original struggles.
Hook & Materials
| Component | Material |
|---|---|
| Hook | Partridge K15DE or D4ef, size 4–10 |
| Thread | Semperfli Classic Waxed 6/0, orange |
| Tail | Elk hair, dyed orange, stacked |
| Underbody | Orange dubbing — angora or Sub Seal, Monster Bush Fur, sparse |
| Abdomen | Orange elk hair, three bound segments over dubbed underbody |
| Abdomen Hackle | Ewing Brown dry fly hackle, palmered through abdomen |
| Wing | Fine natural elk hair, stacked, tied flat and low |
| Thorax | Orange dubbing, fuller than abdomen |
| Thorax Hackle | Ewing Brown dry fly hackle, 3–4 turns |
| Head | Orange thread |
The key difference from Bird’s original: The dubbed underbody beneath the elk hair segments is what separates this pattern from its predecessor. It stabilizes the abdomen segments, prevents slippage under fishing pressure, and gives the body a slightly fuller, more consistent profile that reads better in clear, slow water.
Tying Instructions
Step 1 — Hook and Thread Base
Mount a Partridge K15DE in the vise, size 4 or 6 for salmonfly hatches. Lay a smooth orange thread base from the eye to a point directly above the barb. No gaps — the thread base and the dubbed underbody that follows are the structural foundation the rest of the fly depends on.
Step 2 — Tail
Stack a moderate clump of dyed orange elk hair until tips are perfectly aligned. Length equal to the hook shank. Tie in with progressive-tension wraps — three soft turns, then tighten incrementally. The tail should point straight back with a slight natural splay. Trim butts at a taper, cover with thread.
Step 3 — Dubbed Underbody
This is the step that distinguishes the Improved Bird’s Stone from the original. Spin a sparse amount of orange angora or Haretron dubbing on the thread and wrap forward from the tail tie-in point to the two-thirds mark on the shank. Keep it sparse — this is an underbody, not a finished abdomen. The dubbing creates a foundation that the elk hair segments bind against firmly and stay bound against.
Step 4 — Hackle
Tie in a brown dry fly hackle by the tip at the base of the tail. Strip the base fibers, bind flat along the shank. This will be palmered forward over the dubbed underbody and elk hair segments.
Step 5 — Abdomen Segments
Cut three equal clumps of dyed orange elk hair, underfur removed. The clumps should be slightly smaller in diameter than those used for Bird’s original — finer fiber produces tighter, more controlled segments over the dubbed underbody.
First segment: Tie in at the tail base, tips rearward. Bind firmly at the one-third point, pulling the segment slightly forward to create a rounded lobe. The dubbing beneath gives you something to bind against — use it.
Second segment: Tie directly in front of the first, bind at the two-thirds point.
Third segment: Tie in front of the second, bind just short of the two-thirds mark. The three segments should sit tightly against each other with no gaps. The dubbed underbody will show at each binding point, creating a subtle segmentation effect that the original’s bare hook shank didn’t produce.
