A giant insect that can grow to nearly 10cm and weigh as much as a mouse is showing signs of recovery after decades of decline.The wētāpunga, New Zealand’s largest giant wētā species, was once found across parts of the North Island but disappeared from the mainland after habitat loss and introduced predators drove its numbers down.According to the Department of Conservation (DOC), the species’ decline began after early European settlers cleared large areas of land for farming, destroying much of the wētāpunga’s habitat. Introduced rats, stoats and other pests added further pressure, causing populations to fall dramatically and eventually disappear from all areas except Te Hauturu-o-Toi, also known as Little Barrier Island.By the 1990s, the species was considered endangered. With the remaining population too small for direct translocations, conservationists developed a captive breeding programme to increase its numbers before releasing the insects into suitable habitats.
Breeding programme begins
The programme began with a small number of wētāpunga collected from Little Barrier Island and taken to Butterfly Creek, where conservationists worked on developing reliable breeding methods.The first captive-bred insects were released on Motuora Island in 2010 and Tiritiri Matangi Island in 2011. Auckland Zoo established a second breeding colony in 2012, helping researchers refine methods for raising the insects.Young wētāpunga nymphs are fed fresh foliage and leaf litter, along with fish-flake protein. The additional protein is particularly important during the earliest stages of their development.Over the past 15 years, conservation teams have carried out 45 translocations involving more than 11,000 wētāpunga. The insects have been released at 10 new sites, including predator-free islands and fenced mainland reserves.
Four generations born in the wild
The releases are now showing signs of longer-term success.At least four generations of wētāpunga have been born in the wild on Motuora and Tiritiri Matangi. The presence of multiple generations indicates that populations are reproducing without relying solely on continued releases from captive breeding facilities.The species’ conservation status has also improved. It was classified as “Threatened Nationally Endangered” in 2004 but was listed as “Threatened Nationally Increasing” in 2022.Community restoration groups have also played a role by raising funds, helping organise releases and monitoring the insects after they were returned to the wild.Ngāti Manuhiri, the kaitiaki and mana whenua of Little Barrier Island, has supported the programme. The iwi regards the wētāpunga as a taonga species.
One of the world’s largest insects
The wētāpunga is the largest species of giant wētā and the heaviest orthopteran in the world.Females can weigh about as much as a mouse, while their bodies can reach around 10cm in length. Their legs can give them a span of roughly 20cm.Despite their size, the insects remain vulnerable to predators and habitat changes. Their disappearance from mainland areas illustrates the impact introduced species can have on native insects that evolved without such predators.The conservation programme has therefore focused not only on increasing numbers but also on establishing populations in places where the insects can survive and reproduce.
Methods could help other threatened insects
Chris Green, an honorary research associate at New Zealand’s Department of Conservation and co-author of the study, said the future of the wētāpunga looks promising. The researchers documented the breeding and release programme in a study published in the New Zealand Journal of Zoology, noting that the methods could also provide useful information for conserving other threatened invertebrates.Green described the scale of the programme, involving more than 11,000 releases, as extraordinary.The breeding techniques are already being used to inform conservation work involving the Māhoenui giant wētā at Ōtorohanga Kiwi House. The knowledge could also benefit conservation efforts for species such as the Canterbury knobbled weevil and native stag beetles.The programme has expanded the wētāpunga’s presence beyond the single island population that remained in the wild. Continued monitoring will help determine whether the newly established populations remain self-sustaining.