Try Scud Back on your next Oliver Edward's Freshwater Shrimp pattern.
Scud Back has many uses. Use for shellbacks on scuds, wingcases on nymphs, or wrap for abdomens on many patterns. Scud Back is a stretchable fly tying material that is used to create a shell back on scud patterns. It is also used for tying scuds, shrimp, and crayfish patterns. Scud Back is a soft, flexible, stretchy material that is thin, textured, and translucent. It is available in wide (1/4 in. wide) and narrow (1/8 in. wide) widths.