The Cosseboom was originally tied with an olive green body, silver tinsel ribbing, grey squirrel tail wing, and a lemon-yellow hackle tied as a collar after the wing was applied, with a red head. Other body and hackle color combinations have evolved, but all retain the grey squirrel tail wing. The Cosseboom remains a very popular and effective Atlantic salmon fly and is used worldwide.
Sources
Atlantic Salmon Flies & Fishing, pp. 235–239, by Joseph D. Bates, Stackpole Books, Harrisburg, Pennsylvania, 1970.