A fly hook is any one of a great number of hand or machine-made hooks and lures intended for use in fly fishing and therefore equipped to resemble the insects, such as flies, on which fish feed. These hooks are generally considered advanced equipment used primarily by professionals and experienced amateurs.
Fly hooks are named for their colorful imitations of flies and other insects. They often incorporate synthetic and organic materials to more closely reproduce the glints of light thrown off by insect carapaces in order to entice specific species of fish to take bait and bite down on the hook.
Fly hooks are longer than typical fishing hooks because they incorporate non-living bait and must be able to support it and give it room to move with the current in a manner attractive to fish. They are also typically sized to the fish they are meant to help catch, enabling them to hook them more efficiently for cleaning or release.
Fly hooks serve in various types of fly fishing, from still water to rapids. They are made along various lines in order to work as more effective lures in these different environments, and some actually incorporate elements of the dead insects that they are meant to represent.