Mimopeus opaculus
I associate this large darkling beetle with predator-free offshore islands, yet Andrew Crowe in “Which New Zealand Insect” says it is common on the mainland south of Auckland.
It’s probably fair to say the animals on islands in Cook Strait and Marlborough are larger than normal though. Mimopeus opaculus is about 20 mm long and is common on Puangiangi, having survived rats and now apparently thriving. They congregate under cover in the daytime and feed at night, being seen on the ground and on tree trunks.
Of the 150 species of darkling beetles in New Zealand, there are several on the island and I have earlier posted some photos of the smaller Artystona rugiceps. Its common name, which I am not convinced is commonly used, refers to the grubs. Mealworms, used for feeding robins among other fun activities, are the grubs of Tenebrio molitor, which is in the same family.
The animal below has a very small passenger or parasite behind its right eye. The mite is under 0.5 mm long:
Fauna Recovery New Zealand 