The Whirligig Beetles are found in clusters on the surface of still lakes and ponds. These rapid swimmers can also be found beneath the surface of the water. Both adults and naiads are predators. Adult beetles feed on insects that fall on the water's surface, while the naiads feed mostly on aquatic insects, including other whirligig beetles. An interesting feature of the whirligig beetle is the divided compound eyes that allow them to see both above and below the water's surface at teh same time. Whirligig beetles have a specially adapted antennae to detect small wave motions on the surface of the water.

Sources:
www.unl.edu
www.canadianbiodiversity.mcgill.ca