Although there are hundreds of types of flies used for fly fishing, most of them fall into five specific categories, or types. These types are dry flies, wet flies, nymphs, streamers and buck tails, and terrestrials. The main purpose of the fly is to imitate an insect that the fish wants to eat.
A dry fly imitates a natural insect that is floating on the top of the water. Fish are very sensitive to any motion of their water and how currents move the insects they want for food. In fly fishing, if a dry fly is moving even slightly against the current, the fish will have nothing to do with it. The fly may look like something the fish recognizes but it is not acting the same an insect would. The fish recognizes it as something foreign in the water and leaves it alone.
In fly fishing, a wet fly is imitating a drowned, or drowning, natural insect and is fished below the water surface. No one is sure if the wet fly is seen as a drowning adult insect or a nymph from the perspective of the fish. Most fly fishermen today seem to believe that it is seen as a nymph. Because of this less and less wet flies are being sold. Wet fly fishing is the oldest form of fly fishing. It dates back to descriptions of the early Macedonian people.
A nymph is the stage between an egg and the adult in the life cycle of an insect. In fly fishing, flies that resemble nymphs are growing popularity. The nymph fly is just below the surface of the water. When a fish bulges the water without breaking the surface, he is nymphing. This means that the fish is eating the natural nymphs just as they are emerging from their shell. This is what a nymph fly imitates.
Streamers and buck tail flies do not imitate any part of the insect’s life cycle. These types of fly fishing flies are much larger and represent small bait fish such as sculpin minnows. The main difference between theses two types of flies is that streamers are tied with feathers, and bucktails are tied completely with hair. Fly fishing that uses these two types of flies generally requires more rod and line manipulation. The movements are supposed to duplicate the motions of the little fish.
Although most flies represent water insects, a terrestrial fly is made to imitate a land insect that has fallen into the water. The two most common terrestrials that are imitated for fly fishing are the ant and the grasshopper.
Besides these basic five categories of flies, there are many other kinds of flies that are used for fly fishing. Some of them are a combination of one or more of the basic categories and some do not fit into any group. The most important thing to remember is that it doesn’t matter how the fly looks to you, the fisherman. It matters how the fly looks to the fish.