This is the famous Chocolate Drop sedge invented by Dennis Moss. He states " This is my most effective Sedge pattern. I fish it in sizes 10-14 and find the smaller sizes can be very good when trout are feeding on the medium dark coloured sedge flies or the Welshman’s button. But it is in the larger size 10 that I have found this fly most effective – from July through to the end of season. The Chocolate Drop has taken a lot of big brown trout, and for an evening session in the summer or early autumn, it is a “must have” pattern”. (Quote from "Trout and Salmon - The Essential Guide to Irish Lough Fishing" by Dennis Moss.)