TUSKED WĒTĀ

Motuweta isolata

Males of this species are noted for their very obvious mandibles, giving rise to the name tusked wētā. The territorial males use their mandibles in shoving contests, each attempting to flip the other over.

Description: This species can reach 90mm in length. Males have large, brown mandibles that project forward. Females lack the tusks but have an ovipositor on the rear end. Colouring is often red-brown, particularly around the head region. Legs are tan.

Habitat and distribution: Found only on the Mercury Islands, near Coromandel, and Repanga Cuvier Island to their north, they live in burrows in the ground. Originally discovered on a single island (Atiu Middle Island) in the Mercury group, it appears to have gone extinct there, with no sightings since 2001. Fortunately, the decline in population had been noticed in the 1990s and a captive breeding programme was instituted. This was sufficiently successful to allow the establishment of new populations on two other islands in the Mercury group. There have been further introductions to other islands in the group, as well as to Repanga to the north. The captive breeding programme has undoubtedly saved this species from immediate extinction, but the entire population of tusked wētā is descended from a single male and two females, so genetic diversity is very limited.

Motuweta isolata is a fully protected species under the Wildlife Act 1953.

Biology: Eggs are laid in small depressions in the soil. Captive rearing indicates that these insects take about 18 months to mature. They spend a lot of time in their burrows, only emerging to feed on moonless nights, possibly as a way to avoid predation by tuatara and other reptiles. Unlike most wētā, this species is largely carnivorous, feeding on worms and insects.

Status in Aotearoa: Endemic