The Spent Male Mayfly represents an adult male mayfly lying exhausted after the mating flight. Its spent-wing profile sits flat in the film, a distinctly different presentation from an upright dun or hatching emerger.
Fish it during spinner falls when naturals are lying flat and trout are making measured rises. Use a fine, degreased tippet and place the fly accurately in the feeding lane without adding movement. An excellent fish catcher - few moments beat watching a trout lift and take it cleanly.