Polly Rosborough was a great inventive fly tier from over 60 years ago. He basically invented the "fuzzy nymph", that concoction that seemed loosely tied but gave the impression of "life" due to the natural flowing materials used in it's construction. Tightly wrapped bodies on his nymphs were not to be found. Light reflecting natural fibers applied with dubbing loops were. They worked. In the last years of his life he tied mostly for collectors and his flies were always in demand.
His BEAVER NYMPH and his CASUAL DRESS applied beaver in it's construction but any buggy (I like Australian Possum) fur will do. I apply very thin copper wire although Polly didn't. It never meant that I was creating a "variant" of his fly but just putting my personal preference to it. It's still Polly's fly!
One material that is in these two flies is a thorax of ostrich herl. This is now becoming a forgotten material but it REALLY works on the two flies mentioned here.
The Casual Dress
Size 12 nymph hook
Use wire weight if you want but Polly never used weight. It works well with a micro shot
Australian Possum on a dubbing loop or just loosely dubbed on the hook
The finest copper wire available if you want it. Use a dubbing brush to work out the fibers after you wrap the wire on.
Use a long strand of ostrich herl to wrap over the thorax area and you are done.
No need to coat this fly in plastic. You will absolutely kill it as you will with all dubbed bodies. Let those fibers breathe and you will do well!!!!! I used them late Sunday afternoon on the Millers and I did well!