Natural side Mallard feathers are black-and-white barred for tying realistic nymph legs, tails, and wing cases; or for tying wings on more traditional dry and wet flies. These Mallard feathers are also dyed a deep yellow for a close imitation of natural wood duck feathers, essential fly tying material for Catskill-style dries, wets, and nymphs. Mallard Duck Side Fly-Tying Feathers Orvis