F Flies and Shuttlecock flies popular for the CDC or Cul de Canard which is a soft fluffy material which floats really well. It has air trapping qualities which can have a bubbling effect common in emerging hatches. The F Fly is one of our top selling trout flies in various colours and is becoming more and more recognised. The "F” fly is a very simple fly that is quick and easy to tie but it has all the right qualities needed by any artificial to be really successful. The F Fly is a simple but deadly fly created by Marjan Fratnic. He was acquainted with the Moustique series of flies from the Swiss Jura. However Marjan believed that they were delicate and so he developed the F Fly. Using the feathers from a duck's gland these flies are super for trout and greyling.