Paul Buck, of Central Otago, asks :-

I recently photographed wasps building a nest amongst rocks in Central Otago. What type of wasp does so?

Anthony Harris, an entomologist at the Otago Museum, responded.

The wasp nesting in the rocks in Central Otago is the Asian paper wasp, Polistes chinensis. It is 17 mm long, attractively streamlined, and patterned in yellow and black. The black second segment of the "gaste", or abdomen, bearing a yellow oval area on either side and clearly visible in the photograph, is distinctive. It occurs throughout the North Island, and is extending its distribution through the South Island. The Asian paper wasp has become established in Central Otago in the last two or three years, but has not yet reached Dunedin.

As in all Polistes species, nests of the Asian paper wasp have only a single layer of cells, made under a base of flat wasp paper, and have no protective outer covering. Adults are of similar size, there being no queen and worker casts.

Asian paper wasps capture caterpillars, which they cut up with their mandibles as they fly with them to their nests to feed to their larvae.

The native range of the Asian paper wasp includes parts of China and Japan. It has an annual life cycle. Nests are initiated by a single female in Spring. This foundress queen lays eggs, forages, and feeds the developing larvae. These eventually pupate in capped cells. The emerging females then take over foraging. The original foundress queen continues cell construction and egg laying.

The last stage of the colony occurs in Autumn, when males are produced. These differ from females in having antennae with an extra segment and are bent over sharply at the tip. Also, unlike the female, the face and underside of the body of the male is bright yellow. After mating, nests are usually abandoned in autumn, and fertilised females hibernate, often in clusters, in sheltered cavities.