Stonefly Nymphs 

Stonefly Nymphs usually represent an important food source for hungry trout.  The nymphs crawl around on the bottom and are often swept away in the current.  They are generally poorer swimmers, hence represent an easy food source in the right circumstances.  As a rule, stoneflies live in fast highly oxygenated water and the nymphs can be quite large.  Salmon fly and golden stone nymphs range from size 10 up to an honest size 2 to 4.  I often fish with heavily weighted stonefly patterns while searching riffles and runs, and will tie a smaller lighter dropper fly on to give me the best of both worlds.  If you don't see a particular pattern you're interested in, please ask. I'm sure I can tie it for you!