WĒTĀ

A fearsome-looking insect commonly referred to as “winged wētā” may look like a flying wētā, but it is not a wētā at all. It belongs to the family of the raspy crickets, which is not native to New Zealand. Like all of its family members, it has the ability to secrete silk from its mouth parts, which it uses to build shelters in foliage.

The black-masked raspy cricket was first detected in Auckland in 1990. Within thirty years, it had expanded its range north to Cable Bay, Northland; east to Coromandel Peninsula, and south to Raglan, Waikato. While sightings in New Zealand became more and more numerous, the insect remained unidentified. In late 2023, Wētā Conservation Charitable Trust chair Danilo Hegg travelled to Queensland, Australia, to trace the raspy cricket back to its population of origin and put a name to the species. In a peer-reviewed study now published in the Journal of Orthoptera Research, Hegg showed that the insect originates from the montane rainforests south of Brisbane, at the border of Queensland and New South Wales.

“The insect is heavily built, has relatively short wings, and is a poor flyer,” says Hegg. “While Australian butterflies do occasionally reach our shores carried by westerly winds, the 2,300km journey across the Tasman Sea is almost certainly too much for the raspy cricket. It is highly unlikely that it would have reached New Zealand by natural means”. Australian insects carried by the wind may land anywhere between Cape Reinga and Rakiura / Stewart Island. The fact that the raspy cricket was first detected in Auckland, New Zealand’s largest import hub, only adds weight to the hypothesis of an accidental introduction by anthropogenic means.

Not only has the black-masked raspy cricket been expanding its range in New Zealand; it has also been building up numbers. Its population density has at least quintupled in Auckland during the past twelve years. And like many other invasive species, it appears to be found in higher numbers in its new territory than in its country of origin. “In Queensland, I could spend a night out and find one or two individuals at most. In Auckland, I was able to capture seven specimens in a two-hour walk” says Hegg.

The black-masked raspy cricket is an omnivore and an agile hunter. Strictly nocturnal, it prowls in the foliage in trees and pounces on any invertebrate that is small enough for it to tackle. Observations conducted in captivity and in the wild have shown that the raspy cricket preys on just about anything that moves at night. Including juvenile Auckland tree wētā, one of New Zealand’s largest insects.

Given its high population density and its predatory habits, there are concerns the invasive insect could have an impact on New Zealand’s native invertebrate wildlife. “There is still a lot we don’t know” says Hegg “we need to study its diet in the wild, and we need to understand whether the black-masked raspy cricket is also taking hold in intact native forest habitats, or only in urbanized areas, where the majority of the sightings are. But it poses a threat that needs to be taken seriously”.

New Zealand’s invertebrates are already being decimated by introduced rodents, mustelids, hedgehogs, cats and wasps. The black-masked raspy cricket is only going to add to their woes.

Research article:

Hegg D. 2025. An Australian raspy cricket established in New Zealand, Pterapotrechus salomonoides (Orthoptera, Gryllacrididae), with notes on ecology and first description of the male. Journal of Orthoptera Research 34(1): 77–94. https://doi.org/10.3897/jor.34.134391