The Perfect Danica by Lars Viberg
Essential materials for tying the Danica Extended: Silicone (Dow Corning 732 works great). Fine Dubbing (I use Master Dub light yellow for the female and olive for the male). A rather thick needle (I have glued one to a small handle for more control).
For more information about Lars Viberg and his wonderful artwork please visit: www.theartofflyfishing.net