Found only on Te Waipounamu / South Island, Rakiura / Stewart Island, and adjacent tītī (muttonbird) islands
New Zealand giant stag beetle
English name: New Zealand giant stag beetle, Helms' stag beetle
Scientific name: Geodorcus helmsi (Sharp)
Order: Coleoptera
Family: Lucanidae
- is found only on Te Waipounamu / South Island, Rakiura / Stewart Island, and adjacent tītī (muttonbird) islands;
- is a large, flightless beetle;
- males are recognisable by enormous mandibles (jaws) as depicted here; in females the mandibles are small and inconspicuous;
- stays under logs and stones in damp forests during the day;
- emerges at night to feed on sap exuding from tree trunks;
- grubs are large and cream-coloured, live in peaty soil, and feed on rotting plant material;
- adults walk very slowly and cannot fly, so they are particularly vulnerable to predation by introduced rats and mice.