click beetle common name for members of the widespread beetle family Elateridae. Also called elater beetle, the click beetle has a hinge across the front of the body that allows it to flex, and a spine-and-groove arrangement on the underside of the body that provides a snapping mechanism. When a click beetle is turned on its back it cannot right itself by rolling onto its short legs. It arches its body upward so that only the ends touch the ground, then straightens suddenly, causing the spine to slide into the groove. This sends the beetle spinning through the air and produces a loud click. If the beetle lands on its back again it repeats the performance. A click beetle also snaps its body when it is picked up, which may cause the predator to drop it. Click beetles have long, flat bodies, generally rectangular, but curved at the ends. They range in length from 1/4 in. to 4 in. (6.4-102 mm); most are black or brown. Most adults are nocturnal leaf-eaters. The larvae, called wireworms , are destructive to a large variety of plants. Some tropical click beetles are brilliantly luminescent. Click beetles are classified in the phylum Arthropoda , class Insecta, order Coleoptera, family Elateridae.