Beetles can be found throughout New Zealand’s mainland and offshore islands, in virtually all habitats.
Few species are true marine-dwellers, but several inhabit rocky shores or sandy beaches – for example, plump, C-shaped sand scarab larvae live under driftwood.
A small group of beetles are aquatic. Pond dwellers include the predatory diving beetles. Algae-grazing riffle beetles and cascade beetles are found in fast-flowing streams. Semi-aquatic species of ground beetles and mud beetles live in sand, stones and mud at stream edges.
Grassland and shrubland
Grassland and shrubland beetles tend to be reclusive. Among them are the iridescent blue or orange flower longhorns, mānuka beetles or kekerewai (Pyronota festiva), and pintail beetles, which may be seen feeding on flowers. The whirr of chafer beetles can be heard as they fly about at dusk.
The forest is a beetle stronghold – the greatest diversity occurs there. The soil is home to root-feeding larvae of mumu and tanguru chafers (Stethaspis longicornis and S. suturalis) – the bright-green adults emerge en masse in summer. Leaf litter hosts a multitude of species, most of them tiny. Predatory ground beetles scuttle across the forest floor at night, and include species of the genera Mecodema and Megadromus, which reach 4 centimetres in length.
Log-dwellers include wood borers like elephant weevils (Rhyncodes ursus) and metallic-tinged jewel beetles (Nascioides enysi). Fungus-feeders and predators such as click beetles of the genus Thoramus also live in logs.
Huhu for dinner
Māori ate the large white larvae of huhu beetles (Prionoplus reticularis), which they called tunga haere and tunga rākau. The larvae feed on the dead wood of native trees and introduced pine. When mature larvae or tataka have emptied their gut contents before pupating, they are considered a delicacy. Adult beetles or tunga rere can be seen flying around lights on spring or summer evenings, and can give a nasty nip when handled.
A range of species can be found high in the forest canopy. These include foliage, branch and stem borers, and predators.
Mountainous areas are home to black-and-white striped speargrass weevils, whose larvae feed on the tap roots of speargrass or Spaniard plants (Aciphylla). Flightless chafers (Scythrodes squalidus and Prodontria species) and moss beetles inhabit high-altitude grasslands and herbfields.
Some beetles have adapted to extreme environments. Subantarctic rove beetles (Baeostethus chiltoni) can survive periods of immersion in sea water, and some water scavenger beetles are found swimming in thermal pools in temperatures as high as 45°C. Blind ground beetles live deep in caves, and diving beetles live metres below the surface in alluvial groundwater.