Our threatened species
The most recent (2022) assessment of the threat classification status of New Zealand Orthoptera lists 157 native taxa. Of these, 18 are classified “Threatened” and are further assigned to one of four categories: “Nationally Critical”, “Nationally Endangered”, “Nationally Vulnerable”, and “Nationally Increasing”.
Sixteen of 18 threatened taxa are shown on this page. Two taxa, both listed as “Nationally Vulnerable”, are omitted because of the following reasons:
Species listed “Threatened, Nationally Critical”
Discovered in 1962 in the western Waikato region, the Māhoenui giant wētā survived in 250ha abandoned farmland covered by gorse. The latter provides shelter from mammalian predators, with wētā survival being nine times higher in gorse than in the surrounding native vegetation. The site was acquired by DOC and vested into Māhoenui Giant Wētā Scientific Reserve. As the gorse is being taken over by native vegetation, giant wētā occupancy has decreased in recent years. Translocated giant wētā populations have established in two fenced eco-sanctuaries and on one predator free island, but numbers remain low. Ōtorohanga Kiwi House initiated a captive breeding programme in 2021.
Confined to dry carpet grass slopes in the Paparoa Range at elevations between 1150 and 1350m a.s.l., this extraordinarily cryptic giant wētā derives its name from its habit of digging deep burrows into the peaty soil. Mole wētā colonies that were discovered in the 1990s and early 2000s are probably remnants of a species that was formerly widespread in the subalpine regions of the Paparoa Range and has only survived in marginal habitats.
Smaller than most giant wētā, this adorable insect inhabits sub-alpine tussocklands and herbfields in the Mt Arthur region of Kahurangi National Park. Observed as far afield as the Gouland Downs and the Tasman Wilderness Area in the 1980s, the species is now restricted to the higher alpine regions in the immediate vicinity of Mt Arthur. Its main threat is likely to be predation by mice and stoats, especially during and after tussock mast years. Largely neglected by the Department of Conservation, the Mt Arthur giant wētā benefits from predator control by Friends of Flora over part of its geographic range. Without adequate conservation action, this species could become extinct within the next twenty years.
Species listed “Threatened, Nationally Endangered”
The smallest among all species of giant wētā, Deinacrida carinata became extinct on mainland Southland and on Rakiura / Stewart Island prior to European arrival, most likely because of predation by kiore (Rattus exulans). At present, the species is only known from three predator-free islands off the coast of Rakiura / Stewart Island: Tikaha / Pig Island, Kundy Island and Herekōpare Island / Te Marama. It is considered highly vulnerable to stochastic events. A captive breeding programme followed by releases onto a larger number of predator-free islands is required to secure its survival in the long term.
A strikingly colourful insect with long, slender legs, the bluff wētā inhabits vertical
cliffs and rocky outcrops with deep cracks where it can hide during the day, in the drier regions of the South Island at elevations between 800m and 1,700m a.s.l. The bluff wētā is currently known from two disjunct populations, on Mount Somers in Mid Canterbury, and in the Seaward and Inland Kaikōura Ranges, as far inland as Molesworth Recreation Reserve. The Mt Somers population is under siege from mammalian predators and is literally hanging by a thread. Monitoring and management are made extremely difficult by the species’ habitat, which is often inaccessible to us.
Deinacrida pluvialis is a large, ground-dwelling insect that inhabits the wetter sub-alpine regions of New Zealand’s South Island, about and west of The Main Divide of the Southern Alps, between the Wick Mountains in Fiordland National Park and the Kaimata Range north of the Taramakau River. Its population has declined dramatically during the past three decades and is now confined to higher elevations, most likely due to predator pressure by introduced mammals.
The Wētā Conservation Charitable Trust has started formal surveys across the species’ geographic range. You can read more about our work here.
A tiny ground wētā known from the drylands of the Mackenzie Country, Hemiandrus ‘furoviarius’ belongs to a species yet to be described. It is part of a dryland species complex comprising four entities, the other three being Hemiandrus ‘Cromwell’ from Central Otago, H. ‘Waimakariri’ from the Castle Hill area east of Arthur’s Pass, and H. ‘rocklands’ from Middlemarch in Otago. While at least one new species will come out of these four tag names, the relationship between the four putative taxa has yet to be resolved. The main threats to the Tekapo ground wētā are habitat loss as drylands in the Mackenzie Country are converted to agricultural use, and predation by introduced mammals, primarily hedgehogs.
The robust grasshopper is one of two grasshopper species protected under the Wildlife Act 1953. It inhabits the braided river beds of the Mackenzie Country, where it camouflages with river pebbles. The main threats to the survival of the species are habitat encroachment by weeds (Russell lupin and crack willow), habitat loss and modification through the construction of hydro power schemes, and predation by introduced mammals. Sigaus robustus is the first insect in New Zealand to benefit from a dedicated predator proof fence, built in 2018 near the Tekapo Canal.
Species listed “Threatened, Nationally Vulnerable”
The Kaikōura giant wētā is a ground-dwelling insect that prefers open habitats near forest edges, on river terraces and above tree-line, from sea level to about
1,200m a.s.l. Its population appears to be slowly declining, matched by a shrinking geographic distribution range. The main threats to the species’ survival are predation by introduced mammals, and habitat loss. The wētā disappeared from the Kaikōura Plains in the late 1960s as these were converted to agricultural land in their entirety. In the Molesworth, trampling by cattle takes its toll on an
insect that shelters during the day in hollows at the base of tussock grasses. Competition for food by mammalian herbivores, mainly hares, sheep and chamois, poses an additional threat.
The Cook Strait giant wētā is a ground-dwelling insect that prefers grasslands with scattered mat-forming plants and low shrubs. It was first discovered in Whanganui in the 19th century, but became extinct on the mainland long ago because of predation by introduced mammals. The species only survived on three predator free islands in Cook Strait: Stephens, Mana and Trio. Following a number of wild-to-wild translocations, wētā populations have since established on Maud Island, on Matiu / Somes Island in Wellington Harbour, in Zealandia Te Māra a
Tāne ecosanctuary in Wellington, and in Cape Sanctuary in Hawke’s Bay. The species suffers from low genetic diversity. Wētā numbers overall remain low.
A tiny ground wētā known from the drylands of Central Otago, Hemiandrus ‘Cromwell’ belongs to a species yet to be described. It is part of a dryland species complex comprising four entities, the other three being Hemiandrus ‘furoviarius’ from the Mackenzie Country, H. ‘Waimakariri’ from the Castle Hill area east of Arthur’s Pass, and H. ‘rocklands’ from Middlemarch in Otago. While at least one new species will come out of these four tag names, the relationship between the four putative taxa has yet to be resolved. The main threats to the Cromwell ground wētā are habitat loss as drylands in Central Otago are converted to agricultural use, habitat encroachment by thyme (Thymus vulgaris), and predation by introduced mammals, primarily hedgehogs.
The Auckland tree wētā (Hemideina thoracica) is common and widespread throughout the North Island north of Palmerston North, and is listed “Not Threatened”. The species comprises eight distinct chromosomal races, which are otherwise identical in their morphology and ecology. One of these races is restricted to Karikari Peninsula in Northland. It is classified “Theratened, Nationally Vulnerable”, because it occupies an area smaller than 100ha and is further threatened by habitat loss.
The Alexandra grasshopper is one of two grasshopper species protected under the Wildlife Act 1953. While it is a natural prey item of native skinks, it is also preyed upon by introduced mammals and by the Australian redback spider (Latrodectus hasselti). Additionally, it faces competition for palatable food plants by the European rabbit. The main threat to the species’ survival however comes from habitat loss in what is already an extremely restricted distribution range. Much of the lowland in Central Otago has been irrigated and converted to vineyards, fruit orchards and pasture. Any uncultivated dryland is being taken over by thyme (Thymus vulgaris), which brings with it deep ecosystem changes and creates a habitat that is not suited to our native grasshoppers.
The minute grasshopper is the smallest species in the genus Sigaus, with adult males measuring less than 10mm in body length. Sigaus minutus lives in the drylands of the Mackenzie Country, from the lower Ahuriri River to Lake Tekapo, at elevations between 350m and 1,000m a.s.l. It is listed “Threatened, Nationally Vulnerable”, because of its sparse population in a restricted range and its forecast rate of decline. Studies have shown that Sigaus minutus benefits from the removal of rabbits or from intense predator control. Rabbit exclusion is thought to benefit grasshoppers by suppressing numbers of mammalian predators (cats and mustelids).
Species listed “Threatened, Nationally Increasing”
The Mercury Islands tusked wētā has been the protagonist of one of the most dramatic stories in New Zealand conservation. A giant wētā for all practical purpose, it is a heavy, ground-dwelling insect that has no defense from mammalian predators. It disappeared across most of its georgraphic range after the kiore arrived with the first human settlers. A single population survived in marginal habitat on 13ha Ātiu / Middle Island, one of two natural fortresses in the Mercuries that had never been touched by a mammalian pest. After the eradication of mammals from the remaining Mercury Islands, three wētā were taken to Auckland in 1993 to start a captive breeding programme, which did not succeed. Another three wētā (one male and two females) were taken into captivity in 1998; their progeny was used to repopulate all of the Mercuries, and other predator-free islands nearby. These three wētā were the last that could be found on Atiu – the original population has since gone extinct.
The wētāpunga is New Zealand’s largest and heaviest wētā. It is an arboreal species that was originally widespread in Northland and in the Auckland region; it became extinct on the mainland around 1870 due to predation by introduced mammals. A single population survived on predator-free Te Hauturu-o-Toi / Little Barrier Island. A captive rearing programme was initiated at Butterfly Creek, Auckland, in 2008, with 18 wētā collected on Te Hauturu-o-Toi. The first releases of captive-reared wētā followed on Motuora and on Tiritiri Matangi Islands in the Hauraki Gulf in 2010 and 2011 respectively. A second captive rearing
programme that started at Auckland Zoo in 2012 built on previous knowledge and took ‘wētā farming’ to a new dimension, resulting in over 8,000 wētāpunga being released on seven predator-free islands in the Hauraki Gulf and in Bay of Islands.
