Randall Kaufmann's "Stimulator"

The Stimulator Story as told by Randall Kaufmann
Many tyer–anglers have asked me about the origin story of the Stimulator and the name. 
To clarify erroneous and fictitious claims, here it is! The pattern that became the Stimulator has its origins on the Deschutes River in Oregon, likely dating back to the 1960s or earlier. My friend, Rick Verheghe (angler-boatman extraordinaire) and I were fishing the Deschutes River near Whitehorse Rapids one memorable evening in 1980. Rick was having amazing success with a fly labeled "Hank’s Special" that he salvaged from a dusty fly bin at the famous Oasis Café in Maupin, owned by legendary Deschutes personality Mike McLucas and his wife Gloria. 

How to Fish the Kaufmann Stimulator
Stimulators are my favorite surface fly and often it is the only fly I tie onto my leader during a day’s fishing. It is versatile. I fish it as an imitator, hatch matcher, attractor and exciter. It is my favorite probe when nothing seems to be happening. It is also a crossover and multiple hatch pattern. I cast it in slow and fast water, lakes (I do not refer to lakes as stillwaters because they are not still), spring creeks, and freestone waters, from Patagonia to the Arctic, lowland bluegill ponds to alpine golden trout waters—for any freshwater fish. I like it in bright sunlight, after dark, and anytime in-between. Depending on its size, shape and colors, and how it is fished or manipulated, the Stimulator can represent stone, caddis, crane, dragon and damsel flies, plus moths, hoppers, crickets, cicada and other terrestrials. Fish it with a natural drift, skate, twitch, drag, and/or dab them across currents. 

It is also effective when fished drowned with the above methods. Sometimes I strip it sunk or skip-skate it quickly across the current. I fish a size 8 as often as a size 14 but sometimes size 16 and 18 produce the best action, especially on slower waters and during small size hatches mid-to late summer. I especially like it for imitating caddis in broken water and for skittering it across lake waters, especially during a traveling sedge (caddis) hatch or as a terrestrial imitation. It is also my favorite adult stonefly pattern, and I adapt it for specific hatches, alternating the size and color. The rubber leg versions are especially useful for attractor style and hopper action. Splat undercut and grassy banks and pockets. Hop, skitter, skate, drown and strip it. After dark a large black pattern skated or chugged can represent anything that might purposely or inadvertently be on or in the water, including terrestrial animals. Even when there is no hatch or surface activity and when a nymph might be more productive, I still fish it because, like any high floating dry fly, it is fun, watching it bounce and glide along currents expecting a visual take every inch of the drift.

Before fishing I spread the wing wide and tall for a broader silhouette, stability, and because it helps trap air bubbles. It also allows light and water to penetrate the wing helping to create realism and translucence, and perhaps the blurred motion of fluttering wings or animation. I always like to fish a “fresh” Stimulator. Once it has become bedraggled or soaked, I tie on a fresh one. 

Stimulator Pattern Variation History
The Stimulator first appeared in the 1982 Kaufmann Streamborn catalog in three colors. As new materials became available and popular they were incorporated into Stimulators. Eventually Umpqua produced 120 combinations—standards, crystal, rubber legs, cdc, foam and combinations thereof. Kaufmanns Streamborn had hundreds of dozens on display. They attracted a lot of attention. Contemporary Stimulators have undergone several metamorphoses. Some are hatch-specific, others impressionistic, representing many stonefly and caddis hatches, including the Black (Pteronarcys), Golden (Acroneuria), Yellow (Little Yellow Stone – Sallies (Isoperla mormona)),  Orange (Dicosmoecus) and so on. There is a Stimulator for every season and water type.                   

I tie Stimulators on Tiemco 200RBL hooks for no other reason than aesthetics, but use any hook you like. I like the tail short and spread wide and the wing somewhat sparse, "airy" and spread wide too. Tie in a mono loop to attach a dropper if you like. Palmered saddle hackle should be stiff and tapered, not oversize. Any color hackle combinations work but my favorites are brown and furnace with natural grizzly palmered through the thorax. Abdomen and thorax dubbing is your choice—I mostly like bright colors. Antron is good. Also, I developed several specific Kaufmann Blends, marketed by Wapsi Fly Co, that are often a mix of a dozen colors of several different materials. Hold them up to the light and their colored translucence is amazing. I like to pick out the thorax. 
Elk is preferred for the wing. Stack and flare it wide. An overwing of calf tail or body hair provides visibility. Add a couple strands of Krystal Flash, other flash or rubber legs if you wish. Pick colors that match your fishing needs. If you like fishing after dark, tie some big black. If you fish Little Yellow Sally hatches, tie small yellow/chartreuse. For caddis, match the color and size, etc. Colors in my fly boxes include yellow, orange, lime, peacock, gold, royal, gray, purple, black, and tan.