Main Features of Different Flies: Dry Flies: it's designed to be buoyant, or land softly on the surface of the water. It typically represent the adult form of an aquatic or terrestrial insect, perfect for freshwater. Wet Flies: it's designed to sink below the surface of the water. Wet flies have been tied in a wide variety of patterns to represent larvae, nymphs, pupa, drowned insects, baitfish and other underwater prey, perfect for freshwater. Nymphs: it's designed to resemble the immature form of aquatic insects and small crustaceans, perfect for freshwater. Emerger: Designed to resemble the not quite mature hatching aquatic insect as it leaving the water to become an adult insect, perfect for trout freshwater. Streamers: it's designed to resemble some form of baitfish or other large aquatic prey. Streamers may be patterned after both freshwater and saltwater prey species. They are a very large and diverse category of flies as streamers are effective for almost any type of gamefish.