The Stimulator is an amazing fly pattern developed by fly tying legend Randall Kaufmann. The Stimulator was originally developed to imitate a stonefly adult. But that is not the only insect the Stimulator imitates. The Stimulator also emulates a grasshopper, caddis or even large drake mayflies! The Stimulator is also a great dry fly for fishing a dropper underneath. The bushy profile and deer hair make the Stimulator a highly buoyant fly. The Stimulator is most often tied in olive, orange, black and yellow. Usually tied in sizes #06-16.