New giant weta

Forest and Bird, Issue 265, 1 August 1992, Page 3

New giant weta

A NEW SPECIES of giant weta has been discovered in the Southern Alps. "The discovery gave us a sense of the excitement experienced by the 19th-century naturalists when they first found our gigantic insects," said Dr George Gibbs, leader of the | search party from Victoria University. "It was something | you would not expect to hap- | pen in the 1990s." The party was following tipoffs from trampers and found the weta under rocks at two widely separated sites, both in tussocky country at quite high altitude bordering the mountain ranges. The first site was at Prices Basin, east of Harihari and the other, 250 km away in the West Matukituki Valley, west of Lake Wanaka. The new giant weta — quite different from the seven recognised species of this extremely large insect — is plain brown, | with big spiny rear legs and a | wide shield behind the head. | It grows up to 7 cm long and weighs up to 12 grams. "One might think that ‘ insects as large as New Zea- | land’s giant weta, among the heaviest of all insects, would be well known by now," said Dr Gibbs. "But not so. Seven different kinds of giant weta are described in the scientific literature but we know | of at least three more which still await formal scientific naming." Giant weta used to be common in many parts of New | Zealand but have been wiped out in most lowland areas by introduced predators such as | rats and stoats. They survive mainly in alpine country or on remote islands. "Although this species has only just been discovered, it is not so much rare or threatened but simply inaccessible," Dr Gibbs said. The new species seems to live in very high rainfall areas on the main divide or to the west of it. This is in contrast to the wellknown giant scree weta which is found to the east of the

main ranges on much drier mountains. "Alpine weta of various kinds live under stones by day and come out to feed on the vegetation at night. Hence, unless we specially look for them, they will tend to pass unnoticed despite their size." The discovery of such a

large and distinctive insect shows how little is known about large slices of natural New Zealand. While both finds were made on DoC stewardship land these areas are outside the formal park system. The major threat to the weta is the degradation of its alpine habitat by introduced species

such as thar. DoC has adopted a thar management policy that will inevitably result in higher thar numbers than could be obtained under a strict control policy. A lax approach to the control of introduced animals in the Southern Alps will lead to a loss of diversity in New Zealand’s unique alpine biota.