There is not a time of year when you can't use stonefly nymphs to catch trout, panfish and and even bass. Stonefly nymphs may live as long as three years in the water before they hatch into winged adults. This means that at any given time there are stonefly nymphs present in streams, lakes and ponds. This realistic looking imitation was designed by Kaufmann Streamborn, and a top seller in his shop. Tied by Pros on Japanese Dai-Riki hooks.