Trout are known to be the most finicky of eaters in the fish family, and tying trout flies must be conducted to a very specific standard so that an angler can obtain his desired trout haulage.
Whether you buy ready-made flies or tying trout flies by yourself, you need to ensure that the flies look real in order to fool the trout into taking the bait.
If the fly doesn't very closely resemble the trout's natural food source, the fish won't bite and you will have an uphill struggle in trying to catch any at all.
There are two main types of tying trout flies: dry and wet varieties.
Dry flies are designed to float on the surface of the water. They are meant to resemble insects emerging from their aquatic larval states or terrestrial bugs caught in the water.
Wet trout flies are meant to sink either a few inches or to the bottom. "Streamers" sink just a few inches and are meant to resemble minnows swimming in the current.
"Nymphs" can also be fished just below the surface, where they are meant to resemble insect larvae caught in the current.
Since the bottoms of trout streams and lakes are often full of insect larvae, nymphs are often allowed to sink completely as another ploy to fool the trout into thinking it's the real thing.
Trout flies come in a wide variety of types, styles and colors making tying trout flies fun. They are widely available at sporting goods stores and through mail-order catalogs and the Internet.