New Zealand’s wētāpunga, the world’s heaviest insect, is showing signs of recovery following a successful breeding and release initiative, conservationists report. Known as the largest species among approximately 70 types of wētā, female wētāpunga can reach lengths up to 10 centimeters (4 inches) with leg spans extending up to 20 centimeters.
Once believed to be extinct on the mainland due to habitat loss and predation from introduced species, the insect’s remaining populations were confined to predator-free offshore islands. However, a concerted effort over the past 15 years has seen tens of thousands of wētāpunga bred in captivity at Auckland Zoo and the nearby Butterfly Creek wildlife facility. These programs have enabled the release of over 11,000 individuals into both island environments and certain protected mainland reserves.
The breeding project developed specialized husbandry techniques to raise wētāpunga in communal groups, with nymphs receiving a diet comprising fresh foliage, fish flake protein, and leaf litter. Once sufficiently developed to fend for themselves, the insects were gradually introduced back into natural habitats. Monitoring conducted on at least two islands indicates that the released populations have established self-sustaining colonies.
As a consequence of these advances, the Department of Conservation has revised the species’ conservation status from “nationally endangered” to “nationally recovering.” Dr. Chris Green, who documented the program’s progress, described the scale of the release as “extraordinary” and noted that such positive results remain rare among New Zealand’s many threatened species.
New Zealand’s unique biodiversity is particularly vulnerable due to high levels of species endemism and the impacts of introduced predators. While the country leads efforts in invertebrate conservation, experts say there are few comparable examples worldwide of captive breeding programs achieving this degree of success at scale.
The wētāpunga recovery initiative is seen as a model that could inspire similar conservation projects. Dr. Green expressed optimism that documenting this work could encourage other institutions to develop and expand their own breeding programs aimed at restoring vulnerable insect populations.