The Yellow Stonefly Bead Head nymph is perfect when trying to match natural stonefly nymphs. The bead head and wire make this fly pattern quite heavy which is perfect for getting your hook deep in the water, near the floor where the fish are.
I always have a variety of these in my fly fishing case when I head out to the river. Stoneflies and mayflies are the most common types of hatches that you will come across. Showing up prepared is ideal to making sure you catch as many fish as possible. I find that having one size of these flies are all that is needed.
When fishing nymphs, strike indicators come in extremely handy. Zinger Fishing offers strike indicators, they can be found here.