Wētā (also spelled weta in English) is the common name for a group of about 100 insect species in the families Anostostomatidae and Rhaphidophoridae endemic to New Zealand. They are giant flightless crickets, and some are among the heaviest insects in the world. Generally nocturnal, most small species are carnivores and scavengers while the larger species are herbivorous. Although some endemic birds (and tuatara) likely prey on them, wētā are disproportionately preyed upon by introduced mammals, and some species are now critically endangered.
Name Wētā is a loanword, from the Māori-language word wētā, which refers to this whole group of large insects; some types of wētā have a specific Māori name. In New Zealand English, it is spelled either "weta" or "wētā". The form with macrons is increasingly common in formal writing, as the Māori word weta (without macrons) instead means "excrement". Words of Māori origin in New Zealand English are both singular and plural.
General characteristics Many wētā are large by insect standards and some species are among the largest and heaviest in the world. Their physical appearance is like a katydid, long-horned grasshopper, or cricket, but the hind legs are enlarged and usually very spiny. Many are wingless. Because they can cope with variations in temperature, wētā are found in a variety of environments, including alpine, forests, grasslands, caves, shrub lands and urban gardens. They are nocturnal, and all New Zealand species are flightless but closely related to winged species in Australia. Different species have different diets. Most wētā are predators or omnivores preying on other invertebrates, but the tree and giant wētā eat mostly lichens, leaves, flowers, seed-heads, and fruit. Male giant wētā (Deinacrida spp.) are smaller than females and they show scramble competition for mates. Tree wētā (Hemideina spp.) males have larger heads than females and a polygynandrous mating system with harem formation and male-male competition for mates. Ground wētā (Hemiandrus spp.) males provide nuptial food gifts when mating and females of some species provide maternal care. Wētā eggs are laid in soil over the autumn and winter months and hatch the following spring. A wētā takes between one and two years to reach adulthood, and over this time will have to shed its skin around ten times as it grows. Wētā can bite with powerful mandibles. Tree wētā bites are painful but not particularly common. Tree wētā lift their hind legs in a defence displays to look large and spiky, but they tend to retreat if given the chance. Tree wētā raise their hind legs into the air in warning to foes, and then bring them down to stridulate. Pegs or ridges on the side of their abdomen are struck by a patch of fine pegs at the inner surface of their hind legs (femur) and this action makes a distinctive sound. These actions are also used in defence of a gallery by competing males. The female wētā looks as if she has a stinger, but it is an ovipositor, which enables her to lay eggs inside rotting or mossy wood or soil. Some species of Hemiandrus have very short ovipositors, related perhaps to their burrowing into soil and laying their eggs in a special chamber at the end of the burrow.
Taxonomy and evolution
Fossilised orthopterans have been found in Russia, China, South Africa, Australia, and New Zealand, but the relationships are open to different interpretations by scientists. Most wētā of both families are found in the Southern Hemisphere. Wētā were probably present in ancient Gondwana before Zealandia separated from it. Rhaphidophoridae dispersed over sea to colonise the Chatham Islands (Rēkohu), the Auckland (Motu Maha), Snares (Tini Heke), Bounty (Moutere Hauiri) and Campbell (Motu Ihupuku) Islands. The present species might have resulted from a recent radiation, which conflicts with those earlier ideas about dispersal of wētā forebears around the Southern Hemisphere (Wallis et al. 2000). Giant, tree, ground, and tusked wētā are all members of the family Anostostomatidae (formerly in the Stenopelmatidae, but recently separated). Cave wētā are better referred to as tokoriro, since they are members of the family Rhaphidophoridae, called cave crickets or camel crickets elsewhere, in a different ensiferan superfamily. In New Zealand there were as of 2014 19 genera of tokoriri, and their taxonomy is under review. Seven new species of South Island cave wētā were named and described in 2019, including Pleioplectron rodmorrisi.
Species
Giant wētā
The 11 species of giant wētā (Deinacrida spp.) are endemic to New Zealand and legally protected. Giant wētā (wētā punga in Māori) are large by insect standards. They are heavy herbivorous Orthoptera with a body length of up to 100 mm (3.9 in), excluding their long legs and antennae, and weigh about 20–30 g. A captive giant wētā (Deinacrida heteracantha) filled with eggs reached a record 70 g, making it one of the heaviest documented insects in the world and heavier than a sparrow. The largest species of giant wētā is the Little Barrier Island wētā, also known as the wētāpunga. Giant wētā tend to be less social and more passive than tree wētā (Hemideina spp.). They are classified in the genus Deinacrida, which is Greek for "terrible grasshopper". They are found primarily on small islands off the coast of the main islands or at high elevation on New Zealand's South Island (e.g. the alpine scree wētā D. connectens), and are sometimes considered examples of island gigantism.
Tree wētā
Tree wētā (Hemideina) are commonly encountered in suburban settings in New Zealand's North Island. They are up to 40 mm long and most commonly live in holes in trees formed by beetle and moth larvae or where rot has set in after a twig has broken off. The hole, called a gallery, is maintained by the wētā and any growth of the bark surrounding the opening is chewed away. They readily occupy a preformed gallery in a piece of wood (a "wētā motel") and can be kept in a suburban garden as pets. A gallery might house a harem of up to 10 adult females and one male. Tree wētā are nocturnal. Their diet consists of plants and small insects. The males have much larger jaws than the females, though both sexes will stridulate and bite when threatened. The seven species of tree wētā (pūtangatanga in Māori) are:
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