Stag Beetle

The male jaws

Male stag beetles are immediately recognisable: their antler-like mandibles are often longer than their body and give them a prehistoric appearance. Despite their size and menacing look, these jaws deliver only a gentle pinch to humans — they are not used for defence or feeding but for wrestling other males. Rival males lock jaws and attempt to flip each other over in contests for tree sap feeding sites and access to females. The male with the largest jaws usually wins.

Larval years underground

The visible adult stag beetle is just the tip of the lifecycle. The larvae spend 3–7 years underground eating rotting wood — old oak stumps, buried roots, and dead wood debris in garden soil are all suitable. The female lays eggs near suitable wood and the larvae feed invisibly for years before pupating. The pupae overwinter in the soil and adults emerge in late May–July.

Adults do not eat

Adult stag beetles have reduced mandibles for feeding and rely largely on fat reserves accumulated during the larval stage. They may feed on tree sap, ripe fruit, or aphid honeydew but have only days to find a mate and reproduce. Males fly at dusk in warm June–July evenings, searching for females with a distinctive lumbering flight.

Habitat loss

Stag beetles have declined dramatically across Britain and Europe due to loss of old trees, removal of dead wood and old stumps, and loss of traditional wood pasture habitats. They are now largely confined to suburban gardens in southern England where old gardens retain decaying tree stumps. Leaving stumps in the ground and burying rotting wood in gardens significantly benefits the species.