Beetle (Metallic green beetle) Megadromus bullatus

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Adephaga
Family: Carabidae
Genus: Megadromus
Species: M. bullatus
Scientific name: Megadromus bullatus

Megadromus bullatus is a large carabid ground beetle with a greenish metallic sheen. It has a slightly knobbly back (elytra). It has very strong jaws. It forms small shallow burrows under logs. 
It occurs sporadically in Otago, Fiordland and Stewart Island. It is relatively abundant in the beech forests of Fiordland National Park north to Haast Pass. 
Its very isolated populations to the east are at relatively high levels in tussock grassland and individuals there are much blacker with a slightly violet iridescence.

Megadromus bullatus 2-001.jpg

These strong jaws can give one a nasty nip.
Megadromus bullatus 4-001.jpg

Thanks to Wikipedia for text and information: