Introduction

Find out how the wētā evolved, why it's threatened and how we are protecting this ancient insect. Students will see why the wētā is unique, assess recovery plans and find out how to improve living conditions for wētā in their own backyard.

In this unit students will find out how the wētā evolved, why it's threatened and how we are protecting this ancient insect. Students will see why the wētā is unique, assess recovery plans and find out how to improve living conditions for wētā in their own backyard.

It links to websites, videos and learning tools which provide practical activities to develop your students' knowledge and skill.

About the resource

Learning levels

  • Primary
  • Secondary 

Topics

  • Native animals
  • Forests and green spaces

Curriculum learning areas

  • Science (Living world)
  • Education for Sustainablility

Achievement objectives

  • Students will explain how living things are suited to their particular habitat and how they respond to environmental changes both natural and human induced.
  • Students will appreciate that some living things in New Zealand are quite different from living things in other areas of the world.

Learning outcomes

  • Students will sort factors on a T chart that show why weta have survived for so long and factors which are leading to their demise.
  • Students will research and publish concise information in a bio-box that shows why the giant weta is so unique.
  • Students will discuss and consider alternatives for successful recovery plans.
  • Students will devise and publish a recovery plan for the giant weta that has good chance of success.

View the resource

DOC and TVNZ collaborated to create this resource "NZ Biology: The big friendly giants - the giant wētā" which was written by DOC ranger Mike Tapp.

View the resource on the TVNZ website.

Contents of resource:

1. What's an insect?

Here's a quick activity to check your students' prior knowledge about insects:

Download the What's an insect? worksheet (PDF, 127K) from the TVNZ website.

2. In days gone by

Students consider why New Zealand has creatures living here that are different to anywhere else in the world. They look at factors that helped the giant wētā survive and factors that are now leading to its demise.

Download the In days gone by worksheet (PDF, 58K) from the TVNZ website.

The worksheet uses the information below and can be done in pairs or groups.

Giant wētā are one of our most ancient types of land animals.

Their design is virtually the same as fossil weta found in Queensland and they date back 190 million years - long before Australia and New Zealand parted company during the split-up of Gondwana.

Weta have flourished and diversified during New Zealand's last 80 million years of isolation and more than 70 endemic species have evolved.

Some reached a gigantic size and without mammals the giants came to occupy the same sort of night-living niche that rodents occupied in other countries.

When rats and mice started living here most giant wētā species couldn't compete. Their food was eaten and they became food for rodents. Numbers plummeted.

Weta grow and breed slowly. Wētāpunga, the biggest of the giant wētā, take around 18 months to reach maturity and they only breed towards the end of their two years of life.

3. Life's essentials

Bio boxes can quickly profile almost any person, place or animal. They're tightly written giving background information at a glance. They answer essential questions like:

  • Weight?
  • Length?
  • Food?
  • Habitat?
  • Threats?

A picture adds value.

Get your students to design a bio box for the giant wētā and find out a few essential facts at the same time.

Useful links are:
Kiwi Conservation Club
NZ Ecology Gigantism in Insects

Useful life cycle information for the bio box is:

  • The eggs are oval-shaped and 7 mm long and 2.5 mm wide. They're laid 50 mm deep in the soil.
  • The nymphs start off as mini - wētā about 5 mm long.
  • They moult (grow out of their skin) ten times before beginning adult life.
  • Adults are about 70-80 mm long but females grow bigger than males.

4. Good place for a giant

Hardly any giant wētā remain on the mainland because they've fallen prey to cats, rats, stoats, ferrets and weasels. They only survive in places where they can be protected from these predators.

Protection and recovery programmes can prove tricky too. Share this story with your students and discuss in class whether they would have approached the problem in a different way.

The wētāpunga, the biggest of the giant wētā has to share Little Barrier Island with the kiore, the Polynesian rat. In the past it was thought that kiore were reluctant to climb the trees that wētāpunga lived in so they didn't have huge impact this giant wētā's population.

DOC rangers eliminated the feral cat population on the island which was great for the birds and lizards, but surprisingly, not so good for wētāpunga.

Kiore were the cats' main prey and now the rat population has grown! That's bad news for wētāpunga. Its numbers are dwindling.

Watch the Meet the Locals episode Mahoenui wētā.

Get the class to focus on looking for these things and discuss them after viewing:

  • What saves these giant wētā from predators?
  • What's the biggest danger for these wētā?
  • Have these wētā evolved any defence systems against rats that really work
  • What feature does the female have that helps the female lay her eggs at a safe depth?
  • What else is being done to protect these giants of the insect world?

5. Saving a species

By studying endangered species of wētā and gathering information on their ways of life, we can establish new populations of giant wētā in safe places.

The Mahoenui giant wētā is an iconic New Zealand species, so the recovery programme wants to significantly improve their management and recovery.

Scientists work out why weta populations are declining, they establish original habitat characteristics and improve the effectiveness of reintroduction and restoration techniques.

In this activity the students devise a recovery plan of their own for the protection of wētā on a mainland site. Download A guide for your recovery plan worksheet (PDF, 63K) from the TVNZ website.

This recovery guide will help them formulate a plan and gives them handy hints that may see them think of ideas like the examples below.

  • Scientists are using miniature tracking equipment, such as tags, tiny transmitters, and lights fastened to the insects' thorax, to help track wētā in their haunts.
  • They collect eggs, hatch them, and raise young wētā in captivity, preparing them for release back into the wild. 

6. Active involvement: motels for weta (an optional extra)

Tree wētā like living in holes in trees but there really aren't that many holes. That's why they dig under stones or chew through rotten logs to make their homes. Wētā motels help bring wētā to your backyard. They're placed in trees, under trees and even on fence posts.

Find out how to build a 3 star or 5 star wētā motel. A one star motel works well too - just hang some pieces of bamboo in a tree!

Wētā prefer motels without windows but some people like to peer at them to see what they're up to.

Make your windows from perspex or plastic from a bottle. You need to be able to remove them for cleaning because they go mouldy and they need shutters.

Wētā will live in motels with windows as long as their gallery is deep.

Wētā adapt well to living in a modified habitat. The females lay 100-300 eggs so if you build a home they like, then wētā will live there and numbers will grow!

Additional worksheet

Wētāpunga worksheet (PDF, 1,951K)

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