Cooper Bug

Cooper Bug

Hook - TMC3761, DAI1560 or equivalent, sizes 8-14

Thread - Black

Tail, Shellback, and Head - Natural deer hair

Body - Black chenille 

Originated by Jack Cooper, this pattern is also referred to as the Cress Bug. 

This fly can be tied in a range of body colors, and you are not limited to chenille as a body material.

Fish Flies: The Encyclopedia of the Fly Tier's Art - Terry Hellekson

From the Internet

Downeaster Jack Cooper invented this simple deer-hair bug back in the 1930s to catch the brook trout that gobbled caddisflies off the surface of his local ponds. The fly worked so well that Cooper applied for a patent. He was denied on the grounds that his bug was too similar to Orley Tuttle’s Devil Bug.