Giant wētā returning to Northland after 140-year absence

A female wētāpunga, or giant wētā, at Auckland Zoo. Photo / Doug Sherring

After an absence of more than a century the giants of the insect world are about to return to Northland.

Giant wētā are among the biggest insects on the planet and the wētāpunga — which weighs as much as a small bird — is the biggest of them all.

If all goes to plan, starting in December these scary-looking yet gentle creatures will once again be clambering through the treetops of the Bay of Islands.

Wētāpunga are the latest species to be reintroduced to Ipipiri, a chain of islands between Russell and Cape Brett, in an ambitious restoration effort called Project Island Song.

Project coordinator Richard Robbins was ''very excited'' by the return of the giant insects.

''It's our first invertebrate species. Project Island Song is perceived as being only about birds but it's not. It's a full flora and fauna restoration.''

The reintroduction was being carried out in partnership with Auckland Zoo's captive breeding programme.

Until recently the world's only surviving population of the species, Deinacrida heteracantha, was on isolated Hauturu (Little Barrier Island).

Starting with 12 wētāpunga caught on the island the zoo has been building up a captive population and returning them to pest-free islands in the Hauraki Gulf.

This will be the insect's first time back in Northland since the 1880s.

A giant among insects

■ New Zealand has more than 70 species of wētā, including 11 species of giant wētā. The wētāpunga is the biggest of them all.
■ Female wētāpunga can reach a weight of 35g, more than a sparrow. They can grow to 20cm long, including antennae.
■ Wētāpunga were once common in Northland and Auckland but introduced pests wiped them out everywhere but Hauturu (Little Barrier Island). They disappeared from Northland in the 1880s.
■ Wētāpunga are tree-dwelling herbivores that hide during the day and feed at night.
■ They live for up to three years and have a complicated, 16-stage lifecycle.
■ Auckland Zoo has bred and released more than 4000 wētāpunga onto pest-free islands in the Hauraki Gulf.
■ Despite their size and fearsome appearance wētāpunga are gentle creatures that were once kept as pets.
■ Wētāpunga are even more ancient than tuatara. They've been around for 190 million years.

Robbins said the plan was to start reintroducing wētāpunga to three islands in December, though that would depend on how many the zoo could breed.

Giant wētā were part of the original fauna of Northland but were but highly susceptible to introduced predators, especially rats, cats and mice.

In pre-human times the only predator of adult wētāpunga was the ruru or morepork.

Robbins said the females looked especially fearsome because of their size and the long spike on their rear.

The spike was, however, just an ovipositor or egg-laying tube, and though he had only handled a few so far, he had found them to be ''very, very gentle'' creatures.

Keeper Julie Underwood holds a wētāpunga at Auckland Zoo. Photo / Greg Bowker

Wētāpunga were arboreal (tree dwelling) and nocturnal, spending most of the day hiding in punga fronds.

They sometimes ate other insects but were mostly herbivorous and performed an important role as a digester of leaf foliage, transferring nutrients from the bush canopy to the forest floor.

''They're one of the missing parts of the New Zealand ecosystem,'' Robbins said.

Project Island Song started in 2009 with the eradication of introduced predators.

Since then tens of thousands of trees have been planted and species such as toutouwai (North Island robin), pāteke (brown teal), tīeke (North Island saddleback), pōpokotea (whitehead), kakāriki (red-crowned parakeet) and Duvaucel's gecko have been reintroduced.

Project Island Song is a partnership between community group Guardians of the Bay of Islands, Te Rāwhiti hapū Ngāti Kuta and Patukeha, and the Department of Conservation.