Larvae are not frequently seen and have a long thorax and long legs. The head bears conspicuous large sickle-shaped mandibles without teeth. The latter surface for air head first and have a ridge or keel on the underside that runs down the thorax and extends into a point. Larval development time is not known for many species in this large family. Some species that inhabit vernal ponds develop into adults in a few months.
Mouthparts are for chewing.
These predaceous insects feed on a variety of aquatic organisms, including small fish. These beetles may be found in nearly any body of water. They fly into small ponds and puddles and can even be found in saline ponds. They are good swimmers and use their legs in unison to propel themselves in a straight line in a jerky fashion. Males of some species have an enlarged portion on the front leg that is used as a suction disc to hold the female while mating.