.........I think of this fly as competition to pink fly fisherman's bobbers (hard foam sheres with a whole and a peg).
Competition that weilds a hook. You can swap out sizes and foam colors to do much the same thing for Golden stones, Hoppers and Crickets. This fly design is a good one but less important here than the material. Ultra light foam is ultra good in the bobber-fly context. I bought it wholesale as boat seat cushion material. Someday one of the distributors will get smart and start selling this stuff. I've had it around since the late 1980s. I talk about it, send samples, blabber it around and still you can't buy it. I'm still procelityzing even now.
2lbs per cubic foot closed cell EVA foam (most fly shop foams are 4-8lbs per cubic foot. Ultra light is good but hard to find.)
Hot pink flat nylon thread (flat nylon does not cut into the soft, spongy almost resinless foam)
Elk hair wing combined with white Zelon 50/50
Rubberlegs sewn into place with a rubberleg needle (a beading needle with a widened eye)
#8 DaiRiki 270 hopper hook
CA glue to hold it together (the foam is not pinched down tight to the shank)
With this fly I knot a trailing tippet to the bend of the fly hook. That's good. But it does limit how far up a fat-butt leader you can mount it.
Alan sent me some tube-fly tubing samples I'll work with soon. If I can find the right pegs I'll make the same fly as a tube fly, so it can be pegged at any point you want. Even an inch or two down from the fly line connection--when desired. I'll post that photo when it happens. Thank you Alan.
Big ones (big Bunyan buggers) you can use as fish-catching bobbers for a heavy stonefly nymph or streamer, in deep fast water. On many Montana rivers 95% of the guided boat trips will spend the whole day pecking away at the edges with small flies. But the first 2 or 3 boats down the river scare those bank dwellers out into deeper water first thing every morning. Where they remain (nearly) unmolested all day long.