CDC Comparadun PMD Cripple Dun. This fly will imitate a crippled (PMD) pale morning dun with its wings stuck in the surface film. Keep you eye out for these because they represent easy targets for hungry trout . On many occasions trout will feed exclusively on these, ignoring many other passing delights. This CDC PMD Cripple Dun dry fly pattern is used in most trout streams throughout North America.