SALMON FLY HATCH

This is the king of the insects on most western rivers, it's BIG.  The nymphs do live 2-4 years in the water so it's not a bad plan to use nymphs that are #10-#8 for general prospecting in streams that have salmon fly nymphs.  The fully mature insects are a solid #4.  If you find yourself dealing with selective trout use various patterns to find out what they like.  With such large flies the trout will become wise to popular overfished patterns.