This fly is tied on a size 12 hook and represents the freshwater shrimp, a very common and abundant trout food.  The body is constructed from grey-brown dubbing, the head from grey-brown hackle, and the eyes and antenna from monofilament.  On rivers fish this fly at any depth with a retrieve to match the speed of the current.  On lakes and reservoirs cast the fly into the margins and allow to drift in the wind, or using a very slow figure of eight retrieve on a calm day.  The fly can be used all season.  On rivers it will take troutin spring, summer, and autumn and in the winter, it can be a killing pattern for the grayling.