Uses: Imitates the nymph of a Hexagenia mayfly (big yellow may). These nymphs have large gills along the abdomen, and one of the keys to this fly's effectiveness is the filoplume pheasant "gills." Hexagenia nymphs burrow into the silty bottom of some lakes and slow-moving rivers. They are rarely available to trout until they start to hatch.
How to Fish
The hex hatch starts after sunset, but a few hours before duns start appearing on the surface, the nymphs become active and are sometimes taken by trout. So a couple of hours before sunset, drop this fly near the bottom and use a lift and drop retrieve. Once the hatch is underway, try retrieving the nymph quickly to the surface with a vertical retrieve.