It is often said that New Zealand is dominated by birds, yet for every type of land bird in the country, there are more than 200 kinds of insects, with the total estimated to be about 20,000 insect species.
Insects are plentiful on sea coasts, forests and mountain tops, but in temperate climates like New Zealand’s, many are hidden underground, in rotten logs, or in places where you have to search for them. New Zealand’s insects also tend to be small and dull-coloured compared with the larger, brilliant tropical varieties, and can easily be overlooked.
A study of Cupola Basin, in Nelson Lakes National Park, showed that the mass of native grasshoppers above the treeline reached 32.5 kilograms per hectare. This was three times greater than the combined mass of introduced pests, deer and chamois. Even so, the grasshoppers did less damage to plants than the mammals.
Of the world’s 29 insect orders, 25 are represented in the New Zealand region. The four missing groups are restricted to very few localities worldwide, so their absence in New Zealand is not surprising. However, two of the most significant orders of winged insects – scorpionflies and alderflies – each have only a single species in New Zealand.
The number of species in the larger orders, such as the flies, beetles and moths, is what you would expect considering the country’s land area and temperate location. But the three freshwater groups – mayflies, stoneflies and caddisflies – are over-represented, meaning that their diversity exceeds predictions based on New Zealand’s size. This could be due to high rainfall during the islands’ evolutionary history, which has created a multitude of streams and rivers. By contrast, another aquatic group, the dragonflies, are relatively poorly represented, with 17 recorded species in New Zealand (of which 10 are found nowhere else).
Biters and stingers
There is an unwelcome abundance of small, black, biting sandflies (Austrosimulium species, called blackflies elsewhere) in wetter areas, their larvae breeding in swift, clear streams. Mosquitoes are also common in some places. New Zealand has no dangerous native stinging insects. Wasps and bees, introduced from Europe, can be a threat to some people.