Details Buggy nymph yarn is commonly used to create bodies for nymph patterns, which imitate the immature aquatic insects that are an important food source for trout and other freshwater fish. Use buggy nymph yarn to form tapered bodies that mimic the natural shape and coloration of nymphs such as mayflies, caddisflies, and stoneflies. The textured appearance of buggy nymph yarn adds realism to your nymph patterns, making them more attractive to feeding fish.