This cosmopolitan insect, also known in New Zealand under the names of German wasp and Waikato wasp, is one of the most recent introductions. Evidence shows that over-wintering queens were accidentally imported from overseas in cargo which was first opened at Te Rapa Air Force Depot in 1944. These queens successfully established nests and their progeny have been efficient colonisers. The spread of the wasp is well mapped. By 1951 it had established itself over most of the North Island and at the present time is throughout the country. The wasp has a vicious sting which it can use repeatedly. It is thus a nuisance to humans. It can, however, be regarded as a beneficial insect because of its predominantly carnivorous diet. For most of the summer the nest is populated by workers and these eat and feed their young on caterpillars, blowflies, and all sorts of insects and spiders. It is thought that the blowfly population of most New Zealand bush areas has been reduced very considerably since wasps have become established. In autumn when drones are being reared, worker wasps forage for the sweet carbohydrate foods required by the drones and hence are attracted to jam, honey, ripe and over-ripe fruits. The wasps live in subterranean nests which they construct with masticated plant fibres. Normally a colony lives for one season with the queens alone surviving the winter, but in New Zealand there have been many instances of colonies continuing in an active state throughout winter and thus developing very large nests. A normal single-season nest may reach a size of about 1 ft in diameter but some New Zealand multi-season nests have reached a diameter of several feet.
by Roy Alexander Harrison, D.SC., Senior Lecturer in Agricultural Zoology, Lincoln Agricultural College.