It is a surprising fact that New Zealand, while possessing a fairly large and comprehensive moth fauna (nearly 1,200 species representative of 33 out of 61 families), is very poorly representative of butterflies, having only 16 species representing two families. Several species are not confined to this country.
Many native moths are of economic importance as pest species, the most notable probably being the subterranean grass caterpillar moths (Oxycanus spp.) which are second only to the common grass grub beetle (Costelytra zealandica) as pasture pests. In exotic forest plantations sometimes the looper caterpillars of the genus Selidosema cause considerable damage. The noctuid moths (rather heavy, large, dusk- or night-flying species) cause considerable damage to many plants. In this group are the “army-worm” caterpillars which, under suitable conditions, devastate large areas of pasture or crops.
The largest moth in New Zealand is the wood-boring hepialid, Charagia virescens, which is green or yellow with silvery wing markings; it frequently appears at night during wet summer weather. Another rather interesting species is the common “bag moth” whose caterpillars live within a suspended tough bag often covered with a camouflage of pieces of twigs, bark, and leaves. The females of this moth are wingless and often do not leave the larval case. This species is known to science as Oeceticus omnivorus and is sometimes responsible for considerable damage to trees, damage which would undoubtedly be of considerably greater importance were it not for the presence of several parasites which normally keep the moth populations to a low level.
New Zealand butterflies lack the brilliance of colour of those of more tropical countries and it is of interest that the really spectacular groups are completely absent from our fauna. The family Lycaenidae, which embraces the “blues” and “coppers”, is represented here but the native species are not spectacular. Many members of this family are associated with ants but in New Zealand this relationship does not appear to occur. The little grass blue (Lycaena labradus) is common in the warmer parts of the country, and the coppers of the genus Chrysophanus are not uncommon on stony riverbeds where Muehlenbeckia grows.
The most conspicuous of our butterflies belong to the family Nymphalidae. It is to this group that the introduced “Wanderer” or “Monarch” butterfly belongs. Dodonidia helmsi is a very attractive butterfly found in beech forest areas but very restricted in distribution. Argyrophenga antipodum is a variable, rather dusky species which occurs in tussock areas, mostly at moderate altitudes, while two species of Erebia, which are almost black, occur in alpine meadows and about high screes and rock faces.
Among our better-known species are the “Painted Lady” (Pyrameis cardui) and the “Red Admiral” (Pyrameis gonerilla) whose caterpillars feed on nettle (Urtica spp.).
by Bruce Boucher Given, M.SC., Entomology Division, Department of Scientific and Industrial Research, Nelson.