It helps to know a little entomology when trying to decide what fly to use to catch Steelhead. Entomology is the study of aquatic insects. The life cycle and identification of these insects are the most important factors of entomology as it relates to fishing and tying flies to imitate them. There are four stages of importance during the insect life cycle. They are larval stage (nymphs), emergent stage (emergers), Adult stage (dries), mortality stage (spinners). Aquatic insect spends most of its life in the larval stage so most of my flies I tie are nymphs. Dry flies (adult) are also popular flies to tie. Many people believe catching a steelhead or trout on a dry fly is the most exciting. I can't disagree. This is where identification of adult hatching flies is helpful. Matching the hatch. The better you know the adult insects flying around on your local river the more success you will have. Using a seine to collect nymphs or just looking under rocks will also reveal the larval aquatic insects that inhabit your river. So do a little research and identify the insects that inhabit your river. Some important insects in Great lakes rivers are Hexagenia, Brown drake, Blue winged olive mayflies, caddis, stoneflies.
Weather and water clarity are also important factors in deciding what fly to use. If it is sunny outside I tend to use flies with some sparkle. Materials like krystal flash and ice dubbing are examples of materials with sparkle. Some believe that sparkle imitates air bubbles which makes a fly look life like. Which in turn will trigger fish into biting. Water clarity is also important. The more turbid (cloudy) the water is I tend to use flies larger and more colorful so the fish can see the fly.
