A dry fly is typically thought to represents an insect landing on, or emerging from, the water's surface as might a grasshopper, dragonfly, mayfly, stonefly or caddisfly. Other surface flies include poppers and hair bugs that might resemble mice, frogs, etc.

Sub-Surface flies are fished to resemble a wide variety of prey including aquatic larvae, nymphs and pupae, baitfish, crayfish, leeches, worms, crabs, etc.

Wet flies known as streamers are generally thought to imitate minnows or similar. In the broadest terms, flies are categorized as either imitative, meaning they resemble some natural food source, or attractive, meaning they contain a medley of triggering characteristics designed to entice fish without representing a common food source.