Stimulator Olive. The Olive Stimulator is a great colour variation of one of North America's most productive dry flies. Most fly fishermen in Canada and the US have an array of sizes and colours in their box. The versatility of this pattern cannot be overstated. It works well a little olive stonefly or Salmonfly imitation. In its lesser sizes is an extremely productive Caddis fly imitation and you won't find a better Sight Indicator. These bushy hackled flies, once dressed with a good splash of floatant will float high & dry even in faster water.