Beetles (order Coleoptera) are represented in New Zealand by about 4,400 known species, about a quarter the number known in Australia. The order comprises 74 families, 55 of which are represented in New Zealand.
Beetles are ubiquitous. They occur in water, soil, forest litter, timber, flowers, fruit, strored foods, skins and furs, clothing and cloths, in decaying animal and vegetable materials, and on animals. In gerneral, the order is recognisable by the presence of hard wing-cases but in some abortive groups these cases are greatly reduced or absent. All beetles go through the usual four stages (egg, larva, pupa, and adult) of the typical insect transformation or metamorphosis. Among beetles are some of man's most serious pest. In New Zealand the common grass grub (Costelytra zealandica) is a good example of an endemic insect which has become a meanace to pasture production. This insect belongs to the family Scarabaeidae, a group which contains pest representatives in all larger land masses of the world. These beetles have larvae which feed voraciously on plant roots (some also feed above ground at night), as well as adults which often defoliate trees and other vegetation. Many serious beetle pests are wood borers of several groups (weevils, longhorn borers of several groups, etc.); others are serious pests as seed feeders (grain beetles, etc.). Not all beetles are harmful and some may be used to great advantage. “Ladybird” beetles (Coccinellidae) are mostly beneficial as predators of scale insects, aphids, and mealybugs. Many “ground beetles” (Carabidae) are beneficial as predators on other insects, while some beetles are useful as controlling agents on weeds.
Among the more conspicuous New Zealand beetles are the “Huhu” (Prionoplus reticularis), a large dead-wood borer of the family Cerambycidae, the black sand-scarab (Pericoptus truncatus) which spends its larval life under drift wood just above high-tide level on sandy beaches, the grass grub beetle, and the manuka beetle (Pyronota festiva). a bright green scarabaeid species sometimes present in countless numbers on manuka during early to mid-summer. This last species is much favoured as food by trout.
by Bruce Boucher Given, M.SC., Entomology Division, Department of Scientific and Industrial Research, Nelson.