Lucanus cervus, known as the European stag beetle, or the greater stag beetle, is one of the best-known species of stag beetle (family Lucanidae) in Western Europe, and is the eponymous example of the genus. L. cervus is listed as Near Threatened by the IUCN Red List.
The European stag beetle is the largest beetle in Europe. Their colour is usually black with reddish elytra (and red mandibles in males). Sexually dimorphic, the males have enlarged mandibles and are larger than the females. Although the male's mandibles seem threatening, they are too weak to be harmful. Nevertheless, females can inflict a painful bite. The resemblance of the male's mandibles to the antlers of a stag, and their use in combat between males, much like with deer, gives the species its scientific and common names.
Adult size varies between different areas of its distribution, for example beetles from Spain, Germany, and the Netherlands are larger than those from Belgium or the UK. Males grow up to 7.5 cm (2.9 inches) in length, and females grow between 3 and 5 cm (1.1 and 1.9 inches).
In Britain, female Lucanus cervus are often confused with both sexes of the lesser stag beetle (Dorcus parallelipipedus). They can be distinguished as lesser stag beetles are smaller, with a completely black exoskeleton, and a larger, squarer head. Another difference is that Lucanus cervus larvae feed on wood below ground, and Dorcus parallelipipedus larvae eat wood above ground.
