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Wētā

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Wētā are a diverse group of approximately 100 insect species found only in New Zealand. They belong to two main families: Anostostomatidae and Rhaphidophoridae. These insects are often described as giant, flightless crickets due to their physical appearance. They are nocturnal, meaning they are most active during the night. Wētā can survive in many environments, including alpine regions, forests, grasslands, and even urban gardens.

Deinacrida rugosa female
Deinacrida rugosa female

Their ability to cope with temperature variations allows them to thrive in these diverse habitats.

Most wētā species have distinct physical traits and behaviors. They often resemble katydids or long-horned grasshoppers, but they possess enlarged, spiny hind legs. Many species are wingless, unlike their winged relatives in Australia. To defend themselves, tree wētā may lift their hind legs to appear large and spiky. They also use a process called stridulation to make sound. This happens when a patch of fine pegs on the inner surface of the femur strikes ridges on the side of the abdomen.

H thoracica Matuku 5 Nov 2016 C James OHanlon
H thoracica Matuku 5 Nov 2016 C James OHanlon

This sound helps them warn foes or defend their galleries, which are holes in trees where they live.

There are several distinct types of wētā, each with unique lifestyles. Giant wētā, belonging to the genus Deinacrida, are large herbivores. They eat lichens, leaves, flowers, and fruit. Some of these insects are among the heaviest in the world. A captive female reached a record weight of 70 grams, which is heavier than a sparrow.

Deinacrida rugosa female
Deinacrida rugosa female

Tree wētā, or Hemideina, are smaller and often live in tree holes. They are omnivores that eat both plants and small insects. Ground wētā, or Hemiandrus, live in burrows and may even build perforated doors to hide their exit holes.

Hemiandrus pallitarsis
Hemiandrus pallitarsis

Finally, cave wētā, known as tokoriro, belong to the family Rhaphidophoridae and feature extra-long antennae to sense vibrations.

The history of wētā is tied to the movement of ancient landmasses. Scientists believe wētā were likely present in the ancient supercontinent of Gondwana. They were present before Zealandia separated from that landmass. Some species of Rhaphidophoridae dispersed across the sea to colonize islands like the Chatham and Auckland Islands.

Motuweta isolata
Motuweta isolata

In recent years, discovery continues. In 2019, seven new species of South Island cave wētā were described, including Pleioplectron rodmorrisi. This shows that our understanding of their taxonomy is still evolving.

Specific numbers highlight the diversity and importance of these insects. The giant wētā can reach a body length of 50 mm. Tree wētā are typically smaller, reaching up to 40 mm. While there are over 100 species, the New Zealand Department of Conservation considers 16 of them to be at risk. This risk is largely due to introduced mammals. Animals like cats, rats, and hedgehogs prey on wētā much more heavily than native birds like the kiwi or weka did.

Hemiandrus pallitarsis
Hemiandrus pallitarsis

Conservationists have used radio beacons to track endangered species since the 1970s.

Some wētā exhibit fascinating and specialized survival traits. Tusked wētā possess long, curved tusks on the males' mandibles. These tusks are used for combat between males rather than for biting. The Raukumara tusked wētā has the unusual habit of diving into streams. It can hide underwater for up to three minutes if it feels threatened.

Motuweta isolata
Motuweta isolata

Other species show maternal care, where females look after their young. Female wētā also possess an ovipositor, which looks like a stinger but is actually used to lay eggs in soil or rotting wood.

Beyond biology, wētā have a place in human culture and technology. The name "wētā" is a loanword from the Māori language. In New Zealand English, the spelling "wētā" with a macron is increasingly common in formal writing. The insect also inspired the name of the famous visual effects company Wētā FX. In the film King Kong, oversized versions of these insects appear as "Wētā-rex." This connection shows how even small, ancient insects can leave a lasting impression on the modern world.

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🖼️ Images & Media (4)
File:H thoracica Matuku 5 Nov 2016 C James OHanlon.jpg
H thoracica Matuku 5 Nov 2016 C James OHanlon.jpg
File:Deinacrida rugosa female.jpg
Deinacrida rugosa female.jpg
File:Motuweta isolata.JPG
Motuweta isolata.JPG
File:Hemiandrus pallitarsis.jpg
Hemiandrus pallitarsis.jpg
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