The Stag Beetle is Britain's largest native ground-dwelling beetle. Adult length is up to 7 cm for males and up to 5cm for females. Male Stag Beetles have large mandibles that look a bit like antlers hence the name Stag Beetle. The females have smaller mouths but their jaws are much stronger.Stag Beetles have dark, violet-brown wing cases with reddish-brown mandibles.

Stag Beetles can fly. The males will fly at dusk from May to August on thundery evenings when the humidity is high, seeking a mate.
The females can also fly but rarely do so, preferring to release pheromones to attract males to them.

Stag Beetle larvae eat rotting wood and roots; but they don't eat living plants or shrubs. Adults are thought to eat tree sap or nothing.

During the mating season, male Stag Beetles use their mandibles to wrestle other males. They try to grab each other, and the winner throws the loser to the ground.

Stag Beetles have a long life cycle, lasting up to seven years from egg to adult, The larvae live 3-5 years. Adult Stag Beetles live only 4 months from May to August, but a few may survive the winter if they can find a warm place to live, such as a compost heap.