The Olive A.P. Emerger Fly is one of the top patterns for imitating a callibaetis mayfly or damselfly nymph. This fly was developed for the shallow lakes of Oregon by well known stillwater angler Denny Rikards. When aquatic insects start to become active, lake anglers are finding the A.P. Emerger to be a one of the most constant patterns they fish. When the fish are difficult to catch, having versatile patterns like this that match a variety of food sources will greatly increase your success.