Weta

Weta in Northland – Wētā, Tokoriro

Hemideina thoracica

Weta are ancient insects that existed alongside the dinosaurs

Wētā are endemic to New Zealand but are related to grasshoppers, locusts, crickets and katydids (all members of the order Orthoptera).
There are multiple species of Wētā and they are divided in two families;

There are multiple species of Wētā

There are multiple species of Wētā, divided in two families;

1) the Anostostomatidae family that includes

• 11 species of giant Wētā,
• 7 species of tree Wētā,
• 30 species of ground Wētā, and
• 3 species of tusked Wētā,

2) the Rhaphidophoridae family that includes 60 species of cave Wētā.

These are only the number of Weta species that has been found and identified so far. There may be many more hiding in caves and dense forests waiting to be discovered.

The Māori name for the Giant Wētā, the largest of the Wētā species, is Wētāpunga, which translated to ‘a God of ugly things’.

Weta in the Tangihua Forest Northland

This article focuses on the Tree Wētās in the Anostostomatidea family, in particular the sub-species called the Auckland Tree Wētā which is the most likely Wētā to be found in the Tangihua Forest.

There are plenty of opportunities to see Wētā in Northland’s Tangihua Forest. They can be found along most of the walking tracks and the Nature Trail and occasionally appear in places that they aren’t necessarily wanted, such as the bathroom of the Tangihua Lions Lodge.

Around the lodge we have constructed ‘Wētā Motels’ that can be opened up to reveal numerous Wētā guests and the occasional big spider. They also frequent our sheds and out buildings

Physical Description

Wētās look a bit like large wingless grasshoppers. They come in varying shades of brown and the different species vary in size and shape from the short-bodied, long-legged cave Wētās to the long, stout, relatively short-legged ground Wētās. Tree Wētās are usually between 40 and 60mm long when fully grown, have relatively slim bodies and legs ranging from medium length to long. The male Tree Wētā has an enlarged head, up to twice the length of the females, with over-sized jaws for fighting. The female looks as if she has a stinger, but it is actually an ovipositor that is used for laying eggs.

Just like grasshoppers, Wētās ears aren’t on their heads but are attached to their front legs.

The male Wētā in the photo opposite on the keyboard hung around my back door and would pay an occasional visit. The male Wētā’s large pincers are used for fighting other Wētā for territory but they can also give a vicious nip, as this one taught me when I tried to move him back outside.

The female Wētā with the long legs jumped out at me from beside the water tank at the Tangihua Lions Lodge

Some local Wetas

Wētā Behaviour

Wētā are large but generally harmless, nocturnal insects that prefer to stay away from people. Their defence displays consist of looking large, spiky and scary but they prefer to retreat rather than fight. If a Wētā really feels threatened it will hiss at you. This is generally considered a good time to leave them alone if you don’t want to experience a painful Wētā bite.

How Wētās communicate

Wētās make noise in a similar way to cicadas, producing a rasping sound by rubbing pegs on the inside of their hind legs across a row of ridges on their abdomen. This method of communication is called stridulating and is generally only done at night.

It is thought that males do this to mark their territories, warning other males to stay away and calling females to them.

Wētā predators and defense mechanisms

Many native birds, like Kiwi , Robin, Tomtit and Morepork quite enjoy a Wētā snack.

To avoid being eaten, Wētā hide in refuge holes during the day where they are usually safe. At night, when they come out to feed, they are much more vulnerable. When attacked or threatened they will raise their spiny back legs above their bodies to make themselves look as large and as scary as possible. When they bring their legs down again they will stridulate, to make a rasping, scratching noise in an attempt to scare the predator away. As a last resort, Wētās will hiss as a warning and bite if they can get close enough.

A Wētās Diet

Most Wētās are omnivores, making the most of whatever food is available. They will prey on small insects and even eat the occasional smaller Wētā. The Tree Wētā mostly eats lichens, leaves, flowers, seed heads and fruits.

Wētā Breeding

Female Wētās have an ovipositor, that looks a bit like a long stinger. They will use this to deposit 100 to 300 eggs inside rotting wood or soil each autumn. The eggs hatch in the following spring, producing tiny Wētā that look just like miniature versions of the adults.

Tree Wētās take one to two years to reach adulthood. The Wētās hard shells don’t grow or stretch so as they get bigger they shed their skin and grow a new outer layer to fit, just like crayfish. This can occur as much as ten times as the Wētā mature.

Once they reach adulthood, Wētā will live for another six to ten years.

Wētā Distribution and Habitat

Wētā are found throughout most of New Zealand and many of the offshore islands.

Tree Wētās prefer to live in the forest where it is dark and damp and there are plenty of places to hide and plenty of food available. They are often found in Mānuka and Kānuka scrub.

They are seldom found alone during the day, happily sharing good hiding spots like holes in trees. They don’t create their own holes but utilise holes already created by other insects, such as the Pūriri Moth Caterpillar, or where branches have broken off trees leaving gaps in the trunk. The hole is maintained by the male Wētā, who chews away any bark growing over the opening.

The largest of the male Wētās set themselves up in the best spots, fighting off lesser males to keep their territory. Fights between the males don’t result in death, but it is not uncommon for Wētās to lose legs and antennae in the battle. The victorious male invites females to live with him, creating a harem of five or more females where there is room.

Wētās Role in the Frost

Wētā have been around for 190 million years, longer then the Tuatara, who is considered an ancient species. They were around before mammals evolved and, because of New Zealand’s isolation, they did not meet any mammals, other than the native bats, until humans arrived. Due to the lack of land mammals the Wētā developed to fill the role usually played by rats, mice and other small mammals. This resulted in them being quite happy moving around on the ground to hunt for prey, although Tree Wētās, as their name suggests, prefer to be up in the branches.

Wētā Significance to Māori

Large Wētā carapaces, or shells, were prized by the Māori, who used them as food pouches when going on long journeys. Although incredibly tough, they could be softened by boiling them for several days in the acidic water of volcanic springs, creating a leathery container. Wētā flesh was regarded as a delicacy.

Threats and Conservation Plan

Wētā have evolved alongside native predators such as birds, reptiles, and bats but they did not encounter mammals such as rats, mustelids, cats and hedgehogs until humans arrived in New Zealand. This means that, like a lot of other native species, they have not had the time to develop defences against these predators and, as a result, their numbers have been declining sharply.

The best way to protect Wētās is to reduce the number of introduced pests.

The Tangihua forest block is managed by the Department of Conservation (DOC). They currently do not have the funding available to put in place the strategies needed to eradicate pests and protect the forest.

The Tangihua Lions Lodge has set up the following programs that you can be a part of;

Tangihua Community Pest Control Area: Targeting pests on farm land with local farmers and the Northland Regional Council

Conservation on DOC Land: Tangihua Lions Lodge Conservation and Education project

Conservation Education: Creating a high quality, accessible educational center surrounded by a fully functional ecosystem for schools and any one else who may choose to use the facility.

Volunteers Options : How you can help protect our native bush.

References

It is very apparent that specific information has been shared online between many organisations. Attributing to the initial source is impossible. As much as possible we have used our own photo’s and the following websites have been used as sources for our information;

• Te Ara The Encyclopaedia of New Zealand,
• Wikipedia,
• DOC website,
• T.E.R:R.A.I.N Taranaki Educational Resource: Research Analysis and Information Network