Gates Au Sable Lodge had the recipe for this ugly little fly. Josh Greenberg mentions this particular pattern in his new book, Rivers of Sand. This book is a fantastic fly fishing read! I recommend you pick one up especially if you are into fly fishing for trout. Josh gives a brief explanation of the fly below. There is a step-by-step provided at the Gates Au Sable Lodge website.
Perhaps the ugliest fly that we sell at the lodge. While simple, it’s not as easy to tie well as it seems. This fly works so well in June it seems like you should buy it next to the salmon eggs and Berkeley Powerbait in your local bait shop. Put a shot of gel on it and go fishing. After you catch a fish, or the fly gets drowned, use the powder floatant to reinvigorate it. Fish alone or in tandem. To rising fish, or as a searching pattern. Definitely the most effective Iso emerger I’ve ever fished.
Hook: #12 Daiichi 1180
Thread: Gray or Olive Monocord
Tail: Dun Rabbit Foot
Body: SLF and beaver dubbing (Brown Olive SLF, Gray SLF, Light Gray Beaver)…use a coffee grinder
Wing: Dun Rabbit Foot