Among the foreign insects that become established in New Zealand, some endanger native plants animals, some are harmless, and others pose economic or health threats. Costly aerial spraying of urban areas targets those species of serious concern, such as the painted apple moth (Teia anartoides), the white spotted tussock moth (Orgyia thyellina), the gypsy moth (Lymantria dispar) and the salt marsh mosquito (Aedes camptorhynchus). The remainder are tolerated because eradication is not possible.
Honey bees and bumblebees
The introduction of some insects has been deliberate. Early settlers realised that without native long-tongued (pollinating) bees, the fruit trees and crops they had brought from Europe would not become established. The honey bee (Apis mellifera) was introduced in 1839 by Miss Bumby of Hokianga, the sister of the Hokianga missionary John Bumby. The bee became widespread, even in native forest and shrubland.
From 1885, four species of European bumblebee (Bombus species) were released. One (B. terrestris) became widespread, but the others (B. ruderatus, B. hortorum and B. subterraneus) although successful, were more restricted in their distribution.
Biological control of insect and plant pests began in 1874, when the eleven-spotted ladybird (Coccinella undecimpunctata) was released to control aphids. By 1991, 242 foreign insects had been released for biological control, 75 of which became established. Between 1991 and 2006 a further 12 species were released, all of which seemed to be successful. The native grass grub holds the record for being the most persistent pest: 24 biological agents were released against it between 1921 and 1981, but none became established.