New Zealand has only 11 known species of ant, probably in part because of its cooler, temperate climate. (In comparison, Australia has about 1,200 described species and an estimated total of twice that number.) Surprisingly little is known about some native ants, and further research may reveal more species.
As a group New Zealand’s ants are less diverse and aggressive than ants on many other land masses. The absence of aggressive ants could have been a factor in the evolution of a rich range of invertebrates in the soil and leaf litter of New Zealand’s native forests.
Māori have many words for ant, including pokorua, pokopokorua, pōpokorua, pōpokoriki, nonoko, rōroro, torotoro and upokorua.
On the move
Torotoro is a northern Māori name for an ant. The word also means scouting or exploring, and may refer to the way ants set off from their colony in search of food. Plant runners are also called torotoro. A rātā vine, with long slender stems climbing up the side of its host tree, is called aka torotoro.
Most of New Zealand’s ant species occur all around the country, mainly in forest.
The southern ant (Monomorium antarcticum) is the most common. This species shows a lot of variation, and it is uncertain whether it is a single species or a complex of several species.
Workers are about 3–4 millimetres long, and can range in colour from orange with darker markings to entirely black. They live in almost all habitats: forest, grassland, dry river beds, sphagnum bogs, rotting logs, and suburban gardens and lawns. They also forage along the shore or high in the mountains. This species is known to gather and store plant seeds. Nests range from small to well populated, with thousands of workers.
Named for the swirls on its head and body, the striated ant (Huberia striata) is slightly larger than the southern ant, and workers range from reddish yellow to black. This one is also abundant and lives in similar habitats to the southern ant.
In some nests, a large number of shells of a small native land snail have been found. It is thought that the ants capture live snails and bring them into the nest, where they feed on them. The colonies can hold hundreds of thousands of workers.
Both the southern and striated ants are found in close association with sap-sucking bugs (some species of the insect suborder Homoptera), which they milk for their sweet excreta.
Large Pachycondyla ants
The largest native ants are Pachycondyla castanea and P. castaneicolor, the biggest workers of which are over 6 millimetres long. These reddish brown ants have a strong sting. While more at home in native bush and forest, they have also been found in urban areas.
Small Amblyopone colonies
The native ant Amblyopone saundersi and the closely related, introduced Australian Amblyopone australis are rather sluggish ants, which make only small nests of up to a few hundred individuals. They hunt underground or in enclosed spaces such as rotting wood and leaf litter.
They sting to paralyse or kill insects and other arthropods, and feed the partially dismembered bodies to their larvae. While they can inflict a painful sting on humans, they are not aggressive.