In the small islands of New Zealand, world’s heaviest insect lives: The Giant weta. There are 70 types of species of weta in the genus Deinacrida of the family Anostostomatidae. The insect is endemic to New Zealand and are examples of island gigantism, which is a biological phenomenon leading to a larger size than their mainland relatives because of their isolation and lack of large predators. A female giant weta filled with eggs can reach up to 70 grams or more!
Despite being the heaviest insect in the world, it’s not the biggest – but still really big.
Wetas are grasshopper-like, brown, flightless, nocturnal insects that have large jumping back legs. There are eleven species of giant weta, most of which are larger than other weta, despite the latter already being large by insect standards. Large species can be up to 10 cm (4 in) not inclusive of legs and antennae, with body mass usually no more than 35 g. But rarely, a female giant weta filled with eggs can reach up to 70 grams or more: one captive female reached a mass of about 70 g (2.5 oz.), making it one of the heaviest documented insects in the world and heavier than a sparrow. The largest species of giant weta is the Little Barrier Island giant weta, also known as the wetapunga. One example reported in 2011 weighed 71 g, and a 72 g specimen has been recorded.
Little Barrier Island (Hauturu in Māori language), lies off the northeastern coast of New Zealand’s North Island. Located 80 kilometres (50 mi) to the north of Auckland, the island is separated from the mainland to the west by Jellicoe Channel, and from the larger Great Barrier Island to the east by Cradock Channel. It is an extinct andesitic volcanic cone, roughly circular in shape, about 6 km (3.7 mi) across, with an area of 28 km2.
The giant weta is usually less social and more passive than other weta species. Though it looks like a big cricket, they are too heavy to fly. They even can’t jump. But some of its relatives, like the tree weta, are more agile and can jump.
The name “weta” comes from the Maori word wetapunga, meaning “god of ugly things” in English. Their genus name, Deinacrida, means “terrible grasshopper”, from the Greek word δεινός (deinos, meaning “terrible”, “potent”, or “fearfully great”), in the same way dinosaur means “terrible lizard”. But they are not terrible actually – they are completely harmless to humans. Their diet consists of plants (even carrot!), other small insects and fruit. What’s more, Wētā related species have been around long enough to see dinosaurs come and go and to evolve into more than 70 different species, all of them endemic to New Zealand.
According to the New Zealand government, all wētā species are under threat. The decline of most wētā is due to three major causes:
- Predation: Wētā have evolved alongside native predators such as birds, reptiles, and bats. The introduction of predators such as rats, mustelids, cats, and hedgehogs has resulted in a sharp increase in the rate of predation.
- Habitat destruction: Caused by human impacts
- Browsers: Modification of weta habitat caused by browsers.