This fly appeared in the Summer 2000 issue of Fly Tyer magazine under the title "Davy Wotton's S.L.F. Caddis". Since that issue I have caught many fish on this fly. I have substituted the SLF dubbing for an antron sparkle blend or any other antron type that I have on hand and has deep sparkle to it (Sow/Scud dubbing shown).  This fly is similar to the LaFontaine's Deep Sparkle Caddis in that it is designed to trap air in the body and pull many "triggers". This fly in particular with its swiss straw wing for structure and sparsly dubbed body excels at pulling triggers. I have fished these in olive size 16 with a clipped peice of sandwich baggie for the wing and have caught countless trout in tough to fish waters. I always carry a few in my boxes and frequently give them away to folks who are not catching!
This is tied in a manner similar to a dubbing loop, the split thread technique....hence the flat waxed thread (uni doesn't split real well). make a sparse mat of dubbing 1-2" long and about 1/2" wide (depending on hook size) and insert into the split thread (at the rear of the hook). Let the thread twist to trap the dubbing and wind forward. It should look really shaggy! Don't worry, you can tease it out at the end of the tie. Then add the swiss straw wing. You will have to cut it to length and width for your hook size, and angle it at the rear. Add sparse hackle in front of this, dub a thick thorax. When almost complete, add two wood duck flank fibers pointed forward (over the hook eye) and then fold them back on the sides and complete the thorax and whip finish. 
I use this during hatch periods, but often fish it as a general probing fly. I fish this deep, usually as part of a tandem rig (a brassie sz 18-20 works great as a tail fly). More often than not you will get a hook-up at the END of the drift as it starts to pull up through the column, because it's an emerger, so don't cut your drifts short with this pattern.
I have begun tying these in larger sizes (up to sz 6) and more "gaudy" colors to fish for carp.