The armoured tank of the New Zealand bush. The stag beetle is defined by a robust exoskeleton and, in males, massive, antler-like mandibles used for slow-motion wrestling matches over territory and mates. These mandibles are too weak to harm humans but can lift rival males and flip them onto their backs. Unlike many of their overseas relatives, several native New Zealand stag beetles have evolved a grounded strategy, losing the ability to fly. In a world historically dominated by avian predators, flightlessness was a trade-off. Wings require energy to grow and maintain. Without them, the beetle could invest more resources in armour and mandibles. But flightlessness also means they cannot disperse easily. Each population is trapped on a biological island of suitable habitat. The larvae spend several years buried deep within rotting logs or damp soil, slowly processing decaying timber and returning vital nutrients to the forest floor. They are white, c-shaped grubs with powerful jaws and six tiny legs. They eat constantly, growing slowly through three larval stages before pupating. A single log can support a dozen larvae, each one carving out its own chamber in the soft, rotting wood. Adult stag beetles are short-lived, emerging in summer to mate. The males fight at dusk, grappling with their mandibles on the trunks of trees. The winner claims the female. The loser drops to the ground, climbs another tree, and tries again. Females are smaller, with shorter mandibles that can deliver a painful pinch if handled. They search for suitable rotting wood, laying their eggs in crevices where the larvae will have food. Many stag beetle species are highly localised, confined to specific forest remnants on offshore islands or isolated mountain ranges. The giant stag beetle of the Mokohinau Islands is one of New Zealand's rarest invertebrates, its entire population restricted to a few trees on a single island. Rats and pigs eat the larvae. Habitat clearance destroys the logs they need. Some species may already be extinct. To encounter a large, antlered beetle moving slowly across the forest floor is to witness a survivor from a much older world. A living relic of a time when the pace of life was dictated by the growth of a kauri tree, not the speed of a human.