The most commonly encountered weta are tree weta (Hemideina) and the two species most people meet are commonly called the Auckland tree weta (Hemideina thoracica), and Wellington tree weta (Hemideina crassidens). Below is a male Wellington tree weta (left) and a female Auckland tree weta (right).

Denniston Plateau weta

In 2012 a Bioblitz was undertaken at Denniston Plateau near Westport, South Island, New Zealand to discover as much about the biodiversity of the rare Denniston Plateau habitat as possible. Among the finds made in 2012 is what appears to be a new species of cav weta. It has so far been found only at the plateau and might be endemic to that area. Although the specimens so far found are not adult, their appearance is distinctive. Males and females are both almost black with an unusual but prominent white marking on the pronotum (the area on the top of the animal just behind the head). Comparison of leg spine counts, shape of the subgenital plate of females and DNA sequence data, with our extensive collection of cave weta, support this as being a taxon that is new to science. At present genetic and morphological information indicate this new species, informally called the "Denniston white-fronted weta", does not fall within the current definitions of existing New Zealand genera. However, our current research into the systematics and evolution of New Zealand cave weta (Rhaphidophoridae) indicates that extensive revision of the family is required. For example see Cook et al. 2010. As part of our work on the systematics of cave weta, we have started developing a web based resource that will help people find out about their weta biodiversity (See the BetaWetaGeta).

In 2011 we spent two nights on Kapiti Island looking for weta. Here are some details on what we found.

Tree weta

Wellington tree weta Hemideina crassidens. This species occurs from West Coast South Island northwards to central North Island. Like most other tree weta it lives in tree holes during the day and emerges at night to feed on leaves, sap, fruit and dead invertebrates, and lay eggs. As with most weta, adult females are recognized by their long ovipositor (egg-laying tube).

Ground weta (Hemiandrus)
The pale footed ground weta Hemiandrus pallitarsus occurs from Wellington through much of North Island. This species is unusual in that the females have a reduced ovipositor and are often mistaken for males. Ground weta do not have ears like those of tree weta on their forelegs, but they do use vibration signals to attract mates. To do this male H. pallitarus perch on a leaf and beat with their abdomen. During mating, males provide their mate with a “food” parcel attached to the sperm package (a nuptial gift).

During our trip we found specimens of a new undescribed species of ground weta that is so far recorded only from Kapiti Island. This species of Hemiandrus is apparently restricted to the island, which is remarkable becuase the island has been seperated from the mainland only since the last Pleistocene glaciation about 20,000 years ago.

This female kapiti ground weta (left) has recently mated and is eating the nuptial gift provided by her mate. She will have mated on this leaf, possibly after being attracted by the drumming of her mate. Soon she will return to the ground to hunt and lay eggs. Females of the related species H. pallitarsus lays eggs and looks after nymphs within the burrow where they hide during the day. Probably the Kapiti species does the same. Analysis is underway to identify the relatives of this species on mainland New Zealand.

Cave weta
There are at least five species of cave weta on Kapit Island.
These include two large species, Pachyrhamma edwardsii and Pachyrhamma longipes. Both occur elsewhere in North Island, but P. edwardsii is also found in northern South Island. Pachyrhamma edwardsii is a boldly striped animal that is our best known cave weta, because it occurs in many caves. Pachyrhamma longipes has, prickly hind legs, but is less well known because it does not usually occur in dense colonies.

The P. edwardsii (below left) is feeding on porride oats, but will eat fruit and dead animals too. Pachyrhamma longipes has spiney hind legs, and adults easily span 10 centimetres (below centre).

Living in tree holes, often with tree weta, are the glossy-backed Talitropsis sedilotti. This species occurs throughout New Zealand and two related species exist on the Chatham Islands. It is present on Kapiti Island, but apparently not at high abundance.

At least two other species are present, belonging to the genera Isoplectron and Miotopus. These and a number of other genera contain a large proportion of New Zealand’s cave weta species, many of which have not been described. They are small and cryptic on the forest floor and there is lots to be learnt about them. Further survey work as part of our ongoing weta programme will allow identification of these species on Kapiti Island and contribute to our understanding of the ecology, biodiversity and taxonomy of New Zealand weta.

Being active at night (nocturnal) means these insects are not eaten by daytime predators. New Zealand nocturnal predators of weta include ruru (morepork), kiwi, weka (left) and peripatus (right), and all are active on Kapiti Island.

Palmerston North museum (Te Manawa) have recently developed a living cave weta display featuring artificial cave, plantings, temperature and humidity control. The display, which will also provide an opportunity to study the behaviour and habits of cave weta, has been populated with cave weta from a nearby site.

The species is one of our largest and better known, Pachyrhamma edwardsii (formerly known as Gymoplectron edwardsii). The large adult size and habit of living in dense groups in caves means this species is encountered fairly frequently by people, whereas most cave weta species are smaller and do not live in caves. In fact Pachyrhamma edwardsii is not restricted to caves either, and populations develop in all manner of situations including disused mine tunnels and long-drops! When not in caves, these weta live in hollow trees and in cavities between boulders, and move out into the forest to feed at night.

This year cave weta nymphs appeared in the artificial habitat showing us that the colony is doing well. Weta are mating and laying eggs, and nymphs have hatched! Robert Kitchin of the Manawatu Standard photographed this nymph (below right).