Everythin’s Bettah with a Wētā! (Wētās)

Insects for Fun!

Wētās are the largest crickets on earth and are all native to New Zealand! In fact, most of them are endemic which means they can't be found anywhere else. There are five different kinds of wētās: Giant wētās, Tree wētās, Cave wētās, Ground wētās, and Tusked wētās, and this episode takes a look at all of them.

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Transcript:

Welcome to Episode 40 of Insects for Fun! This week we have another listener request from a listener named Jamie out in New Zealand! Jamie reached out wanting to share a special group of insects found only in New Zealand, and today we are going to dive right into all the wacky facts about insects known as Wetas.

Weta is the common name for a group of giant flightless crickets found only in New Zealand! There are approximately 100 species of Weta and they are split between two different families. The first family is Anostomatidae and the second is Raphidophoridae. I’m not saying crickets within these families can’t be found in other parts of the world, but what I am saying is that the 100 species that are referred to as Wetas cannot with the exception of a few species that made their way to Australia.

Jamie also informed me that Weta without the macrons means filth in Te Reo Maori which is the native language of New Zealand.

There are five kinds of Weta in New Zealand and I’m going to talk about all of them! There are the Giant wētas, Tree wētas, Ground wētas, Tusked wētas and Cave wētas.

The first and most famous wetas would be the giant wētas with the largest species known as Wetapunga or Deinacrida heteracantha. The genus Deinacrida actually means terrible grasshopper which I think is funny considering how they really don’t do anything bad, and the name wetapunga translates to god of ugly things. They really just can’t catch a break I guess. This weta can reach a length of 100mm or 4 inches and weigh up to 70 grams! This is not the average weight though, I believe on average these insects weigh around 30 grams which is still a lot! Heavier than most sparrows in fact. Fortunately, this is a gentle giant, and feeds mainly on foliage though it will sometimes feed on smaller insects as well. It’s favorite food seems to be native plants with large leaves like the karaka, karamu, mamangi, mahoe, and kohekohe. Wew feels like I’m back in Hawaii.

There are 11 species of Giant wētas and for the most part they look like really big camel crickets, but with a less arched back. They definitely are not like your average field or house cricket but they are nocturnal and spend their mornings and afternoons hiding under fallen palm fronds, ferns, or other large plant debris. In the night these critters come out from hiding to feed in trees or scavenge the ground.

These crickets used to be found through Northland, Auckland, and the great barrier island, but have only been able to survive on little barrier island due to habitat degradation and exotic animals hunting them. Now many of you probably don’t know exactly what it means on a map so I’m going to do my best to explain it. New Zealand is an island country off the southeast coast of Australia, but it actually has two main islands. The north island and the south island. It’s kind of similar to Japan actually in terms of Hokkaido being the north island and Honshu being the south island of New Zealand. Now on this northern island of New Zealand the very north tip is called Northland, and right below that is Auckland. To the east of Auckland in the Ocean there are two Islands. The great barrier island and the little barrier island. For a long time these giant Weta have only been living on the little barrier island, but now thanks to breeding projects in Auckland, the giant wēta is being reintroduced to the northern island of New Zealand! In 2020 Wētapunga were actually reintroduced to Northland which was the first time they had been there in 180 years!

Now that you have an idea as to their distribution let’s get into the life cycle of these chungus crickets. These wēta reach adulthood in around 2 years, they’re a very bulky and large cricket and eggs are laid sporadically for many species between October and December with their life cycles not really reliant on seasons. That being said, the eggs of Wētapunga will stay dormant through winter if laid in the fall. It’s generally agreed upon that giant weta go through at least 10 molts before reaching adulthood.

A really cool fact is that these giant bugs actually filled the role of rodents before land mammals arrived. They have an ancient history with New Zealand that dates back 190 million years which is around 100 million years before mammals appeared here. (WOW)

Now let’s get into Tree wētas! These are in the genus Hemideina and as you might expect are mostly arboreal which simply means they live in the trees! They like to occupy holes in trees which in the insect world are referred to as galleries. You might notice a trend with that word and it's safe to say that tunnels created by or used by insects are almost always referred to as galleries. Anyway, these wēta like to hide during the day in their trees and come out at night to feed on leaves, fruits, and other smaller insects. These ones can be found throughout New Zealand except for southland and lowland Otago.

There are 7 species of tree weta and these insects are social with males often having a harem of up to 10 females. These harems are usually hidden within a hole or crevice of a tree, and males will often fight each other to gain control of them. Male Tree wētas actually have larger heads than females with strong jaws which they use to headbutt and fight each other. You ever see two dogs trying to one up each other by opening their mouths as wide as possible and clashing heads? Well, think of it like that but instead of doggos it's big crickets.

Tree wetas are not as large as the wētapunga, but they are still larger than your average cricket with their size ranging from 4 to 6 cm or 1.5 to 2.3 inches. They also have large spikes on their hind legs which when brushed against the spikes on their abdomen create a loud rasping noise.

These wēta will lift their hind legs in a menacing way if threatened to make themselves appear larger, and upon lowering they create their warning calls.

Before we move on to the next group of Wetas there is an honorable mention for the tree wetas which goes to the mountain stone weta or Hemideina maori. This tree weta no longer lives in the trees, and has actually evolved to use crevices and other rocky hideouts in their alpine habitat. These weta can be found in the southern alps of New Zealand at elevations of 1100 to 1500 meters. Now because these insects have adapted to a colder environment they can actually survive being frozen solid. They are the world's largest insect capable of this, and maybe unsurprisingly they have a very long lifespan as well, up to 8 years. Sometimes it takes 4 years just to reach sexual maturity because the climate is so rough.

Now if you don’t like the cold and harsh alps but want to see one of these you can also find them at lower elevations on the islands of Mou Waho and Mou Tapu in Lake Wanaka, which is a very large lake in southern New Zealand.

Next up on our list would be the Ground wētas! There are over 30 species of ground weta believed to be in New Zealand, and they are all in the genus Hemiandrus. These wēta live in holes or under rocks and moss and can be found throughout New Zealand on both Northland and Southland as well as some offshore islands and even in Australia.

These wēta do not have ears on their legs the same way other wetas do, and as a result, don’t communicate through sounds in the air. They actually drum their bellies on leaves of shrubs and ferns or other substrates which can easily transmit vibratory morse codes. These weta are usually on the smaller side when compared to others with the smallest having an adult length of 7mm and the largest being 30mm or 1 inch in length. These ones really do resemble camel crickets but without the hunched back.

Ground wetas are omnivores which feed at night on fruits or smaller insects. The females usually have long ovipositors but some species don’t which make them difficult to differentiate from the males. This is actually where the genus name Hemiandrus comes from because Hemiandrus translates to half male.

Cave wetas are 60 or species within the family Raphidophoridae. These wēta have very long antennae and long legs built for jumping and they can actually jump 3 meters high.

Cave wētas are nocturnal and feed on plants, but not the leaves! They also feed on fungi, dead insects, and lichens.

The crickets are docile and are actually found most in leaf litter, logs, in between rocks, and tree holes, but there are of course species that live in caves as well. These wēta lack hearing organs similar to the ground wetas and rely on vibrations through the ground to communicate with each other.

They are also on the smaller size for a weta as well with many only being a few cm in length, but there is one very large cave wēta which has a total length from the end of its antennae to the feet of its hind legs reaching a whopping 40cm. That’s over a foot long of wēta, but the body itself is small.

Now it’s time to talk about the Tusked wētas of which there are three known species. There are the Northland Tusked wētas scientifically known as Anisoura nicobarica, the Mercury Islands Tusked wētas or Motuweta isolata, and lastly, Motuweta riparia which can be found in the Raukumara range of the north island. These wetas are named for their large tusks which males use to fight each other, similar to how the tree weta males fight using their large mandibles. The female tusked wētas do not have these long tusks and more closely resemble a ground weta.

As far as behaviors go it seems a shared trait among these wetas are that male duels using their tusks as well as scraping the tusks together to make warning sounds. Otherwise, the species are pretty different. For example the Northland Tusked weta more closely resembles a tree weta and have similar behavior in terms of living in trees with harems, but these ones actually plug up the galleries they live in using shavings and debris mixed with their saliva as opposed to tree wetas who just leave their doors wide open.

The Mercury island wētas are more close in behavior to ground wētas, and take refuge in the soil. These weta used to be found only on the middle island of the Mercury islands but has since either gone extinct on that island or dropped to such a low population that they can no longer be tracked. The good news though is that a breeding project was started just before they disappeared on this middle island and there are new successful populations on the other islands now after clearing the mammalian predators.

The last species referred to as motuwēta riparia is a moderately sized weta up to 36mm in length or 3.6 cm in length. If you’re a US listener that equates to 1.3 inches or so. Now this one is unique because unlike motuwēta isolata this riparia species is found along the coast of northland new zealand in large numbers despite being a ground weta surrounded by predators. That being said, this weta has a really cool defense mechanism and that would be to dive into streams and remain underwater until the surrounding area becomes safe.

Wetas in general are food for introduced mammals like rodents and cats, but they are also preyed upon by lizards such as the tuatara and native birds like the kiwi and weka. Fortunately, there have been great strides in the protection of these incredible insects and a lot of care is continuing to be put into their conservation.

Now before we wrap up I have a fun story regarding wēta that Jamie gave me. Jamie’s parents used to have a cat named Tawa (Love that name btw) which would actually bring wēta to their front doorstep and leave them there as gifts. I think anyone with an outdoor cat has experienced these kinds of gifts before, but in this case Tawa was always bringing home live weta and dropping them off near their shoes. Now as we mentioned earlier weta can make warning signals with their legs when threatened, so whenever Tawa brought one home they could hear the angry warning calls of a weta. They actually had to check their shoes too to make sure none were in there!

I’ve heard of snakes and scorpions in shoes but having a wēta? That’s a new one for me.