Here is my answer to this one.
If it is that cold that the guides feeze l am nt interested to fish with a team of wet flys, those days are gone for me.
The main deal is you need both hands to effective the technique, if it is that cold not so easy as you have to wear gloves, which makes it difficult to control the line.
Can wet fly fishing be productive when water temps are low, yes they can. Fish will feed on midges when water temps are way down below 40, in this case l would go with small soft hackles and wets in size 16 and 18, that is winged flies.
Black and silver spider, Peters Ross and flies of that nature can be killer at times.
Invicta and silver versions are two of the best, well within my top 10 for any trout water in the world.
It would not be the same fly with a CDC wing.
Hen Pheasnt tail is one of the more difficult materials to use no doubt of that.
You must obtain tails that are near on perfect, if they are beat up no use. You want a tail that has perfect feather left and rigth side of the quill equal in definition.
There are a couple of options to form the wing.
1. A section from left and right paired as you would for a winf formed from duck quill.
2. Pull out at right angles to the quill a section, which is cut off, then remarried and folded 1 or 2 times, which is the way l do it. It takes a great deal of practice to get this one down, a rolled wing is more or less same, but not so easy as the individual strands may flare. Works great for mallard and teal and feather of that kind.
You can substitute hen pheasant wing quills, and a few other feathers that have the same overall color tone.
The Invicta is one of the more difficult flies to tie, as it doe's comprise of many parts.
A tail, body, palmered and throat hackle and the wing.
I would suggest here you master some of the more simpler fly patters before you try this one.
Davy.
Davy