I was tying an order of 15 dozen BWO's (18's, 20's and 22's) in a Thorax style and thought you folks might like to know a good feather to use for the wing. Most people use Turkey Flats if they are using feathers. I found a feather that does a better job and is a lot cheaper I use it on all my Thorax and Parachute style flies if using feather wing's or post's. It is finer than the Trukey Flats and works on real small flies much better as there is less bulk.
The feathers I use are the small drak gray ones on the elbow of a Mallard Wing. (Any Duck Wing will work) You can't miss these feathers easy to locate. Just gather the tip up and tie it on the hook as you would a Turkey flat and you are good to go. I use Goose Wing Elbow feathers for larger drakes and if you want a specal color Just get some White Duck Wings and you can dye them any color you like. There are some white feathers that you can use on the underside of a Mallards Wing in the same area as the Gray ones.
These feathers are easy to get and cheap. They work better than anything else I have used including Turkey Flats. I just got to thinking about my use of these feathers. I have used them for this purpose for many many years and most people do not know about them. I think you will find they work real well for this style of fly. Most of the time they are just thrown out. Good Tying Ron