This book presents dressings of sedge-flies and stoneflies in all their forms ranging from nymphs, to emergers, to adults. This includes cripples and stillborns.
Whether you like it or not, you will find polymers, just natural feathers and furs. This choice was not motived solely by the issue of pollution which would be a good enough reason. Author simply have always disliked using plastic.
On the other hand you will be able to experiment with new tying techniques that can make sedge and stonefly wings more robust and at the same time more imitative and buoyant. They are also easier to tie!