World's Heaviest Insect Makes Remarkable Comeback After Breeding Program
The wētāpunga, once critically endangered, has been downgraded in status thanks to conservation efforts that released over 11,000 individuals into the wild.
The wētāpunga, recognized as the world's heaviest insect, is staging a significant recovery from the brink of extinction due to a dedicated breeding program.
Once classified as endangered, the species has seen its status updated to "Threatened — Nationally Increasing" following the successful release of more than 11,000 individuals into predator-free environments. Dr. Chris Green, an honorary research associate at New Zealand’s Department Of Conservation, described the turnaround as a recovery, noting the species was endangered at the program's start.
This colossal insect, also known as the Little Barrier Island giant wētā, can weigh up to 35 grams, surpassing the weight of a mouse or sparrow. Pregnant females have been recorded at an even more substantial 71 grams. Adult females are large enough to comfortably rest on an average hand, and their body length can reach up to four inches, with a leg span of eight inches.
Historically, giant wetas were found across New Zealand's North Island. However, habitat destruction by settlers and the introduction of invasive predators like cats and rats led to their near extinction. Like other flightless species, such as the dodo, the wētāpunga proved vulnerable to these introduced predators.
By the 1990s, their presence was limited to Hauturu/Little Barrier Island, the only remaining wild population on the mainland.
Conservationists employed specialized techniques to revive the species. Experts at Butterfly Creek and Auckland Zoo provided nymphs with fresh foliage, fish flake protein, and leaf litter. They also successfully reared large numbers of the insects in communal mesh cages. These efforts allowed for the rearing of enough individuals to begin reintroduction programs.
The first wētāpunga were released into the wild in 2010. Since then, 11,214 individuals have been reintroduced to predator-free islands and two fenced sanctuaries on the mainland. These releases have resulted in established, multi-generational breeding populations. Surveys in these new habitats have indicated a significant increase in wētāpunga numbers, with one survey finding 28.5 insects per person per hour, compared to 1.4 on Little Barrier Island.
The success of the wētāpunga conservation program offers hope for other endangered invertebrates. Dr. Green expressed optimism that the methods used could be replicated for species like the Canterbury knobbled weevil and native stag beetle species, sharing valuable knowledge on husbandry, release strategies, and population persistence.