The Red Squirrel Nymph (also known as the Red Fox Squirrel-Hair Nymph or RFSN) is a renowned and effective nymph pattern for fly fishing, developed by Dave Whitlock in the late 1960s
. It is known for its versatility, imitating a wide range of aquatic insects and crustaceans, including mayflies, stoneflies, caddisflies, midges, and even scuds and crayfish.
