The PMD Cripple can be one of the more interesting looking patterns in the mayfly series, often overlooked and not used. The fact of the matter is, this fly is a lifesaver when it comes to catching fish. The fly is mimicking the stage in which the actual yellow mayfly is exiting the exoskeleton of the nymph it once was. The fly can sit too long in this process and become easy pickings for hungry fish. There are all sorts of theories as to why these cripple patterns are so effective, but the bottom line is THEY ARE EFFECTIVE. If you have one in your box, or need one, we highly recommend this fly when in a PMD hatch.