ground beetle running down prey under cover of dark
- Size
- Length: 1–3 cm
- Lifespan
- 2–4 years
- Diet
- Predatory: feeds on caterpillars, slugs, snails, aphids and other small invertebrates. Both larvae and adults are active hunters, patrolling soil surface and leaf litter at night.
- Habitat
- Under stones, logs and leaf litter in forests, gardens and farmland. The night watchmen of the soil, patrolling the ground in search of prey.
- Range
- Throughout North and South Islands in native forests, gardens, farmland and urban areas. Most common in lowland areas with well-developed leaf litter and soil cover.
- Endemism
- Native
- Main Threats
- Habitat loss from forest clearance, intensive agriculture and urban development. Pesticide use which kills both beetles and their prey. Competition from introduced ground beetle species.
- Population
- New Zealand has rich diversity of native ground beetles, including giant, flightless species. Beneficial predators but threatened by habitat loss and introduced predators like hedgehogs.
- Conservation Status
- Not Threatened
The armoured tank of the garden path. A beetle that runs and hunts.
Robust, often shiny black or metallic green, and equipped with powerful mandibles, the ground beetle looks like it means business. Most are flightless, having evolved to run rather than fly, with long legs built for sprinting across the forest floor. A beetle that is a sprinter.
They are nocturnal hunters, spending the day hidden under a cool stone and emerging at dusk to patrol their territory. If a rock is lifted and a large beetle is seen darting for cover, a carabid has likely been disturbed. They are voracious predators, feeding on slugs, snails, caterpillars and other insects.
Some species are so effective at controlling pests that they are intentionally introduced to farms as biological control agents. They do not use webs or venom. They simply overpower their prey with brute force and sharp jaws. It is a direct, honest way of hunting that commands a certain respect.
New Zealand is home to some remarkable giants, like the flightless Mecodema, which can grow several centimetres long. These ancient beetles are living fossils, surviving in our isolated islands while their relatives elsewhere went extinct. However, their flightlessness makes them vulnerable. A single hedgehog or rat can wipe out a local population overnight.
They are the stoic guardians of the undergrowth, silent, strong and fiercely protective of their patch of dirt. To find one is to know that the soil beneath the feet is still wild.
Not threatened, ground beetles are foundational participants in the predatory layers of native ecosystems. The garden path is dark. The ground beetle emerges from under a stone, shiny black, powerful mandibles. It hunts. It kills a slug. It drags it away. It does not know it is a guardian. It does not know it is a living fossil.
It just wants to eat. Large native ground beetles were known to Māori. Their imposing size and aggressive defence would have earned them respect. They were seen as part of the hidden people of the forest floor. The ground beetle is proof.