Wētā are endemic to New Zealand. They are quite large compared to other insects, with some weighing more than a sparrow. There are wētā that hiss, bite and wave their spiky legs when threatened, while others leap up to 3 metres! And then there are the wētā with curved tusks designed for combat.
In spite of their fearsome looks, wētā are elusive creatures – more threatened than threatening – and they need our protection. Wētā are important ecologically. Most species are omnivorous – they consume vegetation and small invertebrates. Wētā have to compete with introduced species like mice and rats, which occupy a similar niche. Introduced species tend to disrupt ecological food webs – mice may eat the same things as wētā – but they do not provide food for kiwi or tuatara.
Wētā in Aotearoa
Although the wētā living in New Zealand are endemic – meaning the species naturally live here and nowhere else – similar insects live in many parts of the world. They are not called wētā. This is the Māori common name used exclusively in Aotearoa/New Zealand. Wētā are members of the group of insects that include crickets, locusts and grasshoppers.
New Zealand wētā are grouped into five general categories based on their physical characteristics and ecological habits. These categories are:
- tree wētā
- giant wētā
- cave wētā
- ground wētā
- tusked wētā.
Tree wētā are the most common of New Zealand’s wētā species. They live in native bush and backyard gardens throughout most of the country except for parts of Otago and Southland. There are seven species of tree wētā, and many are associated with specific geographic locations. The wētā species have scientific names, common names and Māori names. For example, Hemideina thoracica is called the Auckland tree wētā or tokoriro, and it is found throughout most of the North Island.
Tree wētā live in holes or tunnels, called galleries. These galleries are initially created and abandoned by other insects, but once the wētā move in, they maintain the gallery by chewing away bark around the opening.
Tree wētā are social creatures. A gallery can have a number of young wētā and females but only one male. The males defend their gallery from competing males. When threatened, wētā wave their spiky hind legs to frighten and/or scratch invaders and predators. They also hiss and bite. Female tree wētā can look pretty threatening, too. They have an ovipositor for laying eggs, but it looks like a very large stinger!
Tree wētā are the species most likely to enter into ‘wētā motels’ placed in schools, parks and home gardens. Wētā are nocturnal, so we don’t often find them during the day, but they can be viewed through the motel/gallery windows. (The student activity Building homes for tree wētā provides some simple designs for wētā motels.)
Giant wētā species have interesting scientific and common names. Their genus name is Deinacrida, which means demon or terrible locust. Māori called them wētā punga – the ‘god of ugly things’. At their largest, giant wētā can have bodies up to 10 cm in length and a leg span as wide as 20 cm!
In spite of their size and appearance, giant wētā species are slower and less aggressive than tree wētā. They have not coped well with predators that have invaded New Zealand, like rats, and their numbers have dropped. Only a few species live on the mainland – mostly in the Southern Alps – away from predators. Other species are only found on predator-free offshore islands.
The name cave wētā is a bit misleading. While some species of cave wētā do live in caves, many species live in the forest. Unlike other wētā groups, they don’t have hearing organs on their front legs. Cave wētā are known for their very long antennae.
As their name suggests, ground wētā burrow into the soil. They back into their holes so they can keep an eye out for enemies. They emerge at night and climb trees and vegetation looking for food, but if they are not careful, ground wētā become food for kiwi. These wētā species are characterised by slender antennae, which are many times their body length.
Tusked wētā get their name from long, curved tusks – but only on the males. The females look similar to ground wētā. Males use the tusks for combat, and they rub them together to serve as a warning. Species range from a few centimetres in size to the 6.5 cm giant tusked wētā.
Like many of New Zealand’s native species, wētā are threatened by introduced predators and habitat loss. Captive breeding programmes and translocation are helping the survival of wētā. Individuals can help protect all wētā species by trapping rats in their backyard – check out Predator Free NZ for advice.
Weird wētā facts
One species of tree wētā, Hemideina maori, the mountain stone wētā, can withstand being frozen at temperatures below -10°C.
Wētā have to shed their hard outer exoskeleton 10 or more times as they grow to adulthood.
Wētā ears are on their front legs, just below the knee joint.
Large wētā filled the role of rats and mice before humans populated Aotearoa.
Wētā have been around for 190 million years – longer than tuatara.
Wētā are the old fellas in the insect world, living longer than most. Some spend up to 2 years as a juvenile and then live for another 2 years as an adult.
The Raukūmara tusked wētā was not discovered until 1996. It dives into streams when threatened and can stay there for 3 minutes.
Watch entomologist Rudd Kleinpaste as he attempts to replicate life as a mountain wētā Brrr!.
T.E.R:R.A.I.N. (Taranaki Educational Resource: Research Analysis and Information Network) has extensive information on 16 wētā species.
Visit Massey University’s WētāGeta site to see great images to help identify wētā species.
Watch ‘Meet the Locals’ videos to learn more about Tokoriro – cave wētā.