(Pteronarcys)
Characteristics
These are huge insects. The adults are dark charcoal with dark orange thoraxes and underbellies. The nymphs vary from dark mahogany brown to black. They take 3 to 4 years to mature from egg to adult. The nymphs concentrate near the bank and crawl out to emerge. Emergence is specifically concentrated and usually moves upriver a mile or so a day. The egg-laying adults fly clumsily over the water and many of them end up on the water providing explosive dry fly fishing.
Timing of Hatches
Henry’s Fork – May 20 through June 10
Madison River – June 20 through July 5
South Fork – June 20 through July 5
Habitat
Medium to fast, oxygen rich water with rocks and boulders
Comments
Nymphs provide norishment to trout on a year-round basis. There are usually 2 or 3 age classes of nymphs in the water at the same time. Trout can get totally gourged on the nymphs just prior to emergence. Trout can quickly get their fill of adults. The best tactic is to try to work the water upstream from the main emergence with nymphs. The best dry fly fishing normally occurs after the peak of the emergence is over so that trout are more focused on adults.
Patterns
Black or Brown Rubberlegs Nymph, Henry’s Fork Salmonfly, Rouge Salmonfly, South Fork Secret, Foam Salmonfly
Hook Sizes
4 & 6