Biology

Both adults and larvae of this beetle are voracious predators, taking a wide range of prey including fish. They actively search for prey, and periodically swim to the surface in order to take in air (3). Adults often fly at night, and may land on glass surfaces or roads, mistaking them for water (2). When threatened, they exude a foul-smelling fluid from the anus that deters potential predators from eating them (5). Females lay their eggs in cavities, which they cut in the stems of water plants that protrude from the water. The eggs hatch after a number of weeks (5).