Stimulator Black. The Stimulator is one of the most popular dry flies in Canada and the US. It is a versatile pattern that can be used to imitate a stonefly or Salmonfly imitation. In smaller sizes works well as a Caddis fly variation or even as a Sight Indicator with a Match the Hatch dry fly on point or a favorite nymph on a dropper with the Black Stimulator on point. Make sure that you have whole bunch of these in a variety of sizes and colors you won't regret it.