Pale Morning Dun Spinner

Many anglers consider the Pale Morning Dun (PMD) to be the most important fly in the West, even more important than the Blue Winged Olive fly. It has predictable hatches that cover a long period of time. There are two major almost identical species the infrequens and the inermis so the same Super Fly will imitate both of them.

The PMD spinners normally fall in the calmer waters that are upstream from where they have emerged. They can fall both in the mornings and the evenings with warm calm days being best. As with other mayflies, they mate over the water where the males fall dead immediately. Usually, the females flyover the riffles and dip slightly into the water to deposit their eggs, but sometimes they drop them from slightly above the water. After they deposit their eggs, the females will die and fall spent on the water. On occasions the trout will take them as they are depositing the eggs but they are more likely to eat them after they die and fall spent into the water.

When the spinner fall occurs it may be difficult to notice and you may not even be aware of it. Even though there large numbers of them on the water they are difficult to see, especially during the low light conditions when the fall occurs. The trout will be quietly and simply sipping the spinners so it will be difficult to determine what they are eating. Therefore the best way to determine if the spinner fall is occurring is by using a skim net. Use the skim net in areas where the spinners congregate such as slow water below riffles or in the seams of current or in the eddies.