Despite it's name, the pale morning dun can hatch in the morning, the afternoon or evening. It is very common on most western waters, and trout really key in on this mayfly when it starts to move. Take several varieties of the PMD, including the hatchmaster version, because trout can be very selective, shunning one variety, while eagerly taking another.
The hatchmaster series of flies provide the angler with a great surface film fly. The hatchmaster fly is able to represent an emerger with the wings upright or a spinner with the wings down.