Like wasps, bees may be solitary or social. They feed on nectar and pollen, and play an important role in the pollination and survival of many flowering plants. New Zealand has 28 native and 13 introduced species of bee.
At least three native bee species have a basic social structure, a bit like the introduced honeybee and bumblebee. The rest are solitary, although they may make nests close together.
Native bees pollinate many native plants. They are also widespread in kiwifruit and apple orchards and some vegetable crops, and may be important pollinators in horticulture.
The most commonly seen native bees are 18 species of Leioproctus. These bees are robust and hairy, looking similar to honeybees but smaller (5–12 millimetres long). All are black except for the South Island species Leioproctus fulvescens, which is covered with dense orange–yellow hair. They are often seen in summer carrying pollen on their back legs, like honeybees and bumblebees.
They dig nest holes in the ground, and sometimes a nesting area riddled with bee holes gives the impression of a colony. A small pile of soil is the usual sign of individual nest tunnels. Each species prefers a specific type of soil. For example, Leioproctus fulvescens needs fine-grained soil, while Leioproctus metallicus nests in coastal sand.
The seven Hylaeus species are 7–9 millimetres long, and slender. Almost hairless, they are black with small yellow markings on the face and thorax. They make nests in blind tunnels in twigs and branches, or in old beetle holes in logs. They have no special pollen-carrying structure on the back legs, so carry pollen in the stomach.
The smallest (4–8 millimetres long) and most easily overlooked native bees are four species of Lasioglossum. They are black or greenish, only moderately hairy, and nest in the soil. At least one species, Lasioglossum sordidum, has adapted well to modified habitats. Its nests are often found along fencelines, on horticultural land sprayed bare with herbicides, and on stopbanks and ditch sides above water level.