PEEPER, a popular name for several species of the family Hylidæ or tree-frogs, which make a peeping noise in the early spring, when they go to the water for breeding purposes. The title belongs particularly to the small yellowish thin-voiced Pickering's tree-frog (Hyla pickeringii), common over all the eastern United States and in Canada westward to Manitoba. This little frog hibernates during December and January and in very cold seasons through part of February. His is the first voice heard in the spring, either late in February or early March, and he continues “peeping” until the second or third week in May, at which time the other tree-frogs begin their piping. The peeper ranges in color from a light fawn color to a deep wood-brown, and his color varies according to the color of the place where he sits. He is marked with an oblique cross on his back and bars on his hind legs. In size he rarely reaches more than an inch in length. The peeper will become quite tame and may be kept quite successfully in a mossy fernery if fed properly. These little frogs eat prodigious numbers of mosquitoes and gnats, and are themselves eaten by larger frogs. See Tree-frogs.