Identification

Social wasps, which include the hornet, are social insects that live in papery nests made from chewed up wood fibres. Most social wasps are black with yellow bands on the abdomen and yellow markings on the head and thorax. The hornet (Vespa crabro), which is significantly larger than other wasps, is largely brown with yellow banding on the abdomen.

Wasp nests are initiated by a fertile female (queen wasp) during late spring. The initial nest is about the size of a golf ball and contains a small piece of comb in which the queen rears her first brood of worker wasps. The workers are sterile females. Their role is to gather food that they feed to the larvae, to gather chewed up wood fibres for constructing the combs and enlarging the nest, and defending the nest against intruders. Male wasps and next year’s queens develop in late summer.

Size

The queens are the largest individuals. They are generally about 20mm long but a queen hornet is about 35mm. Worker wasps vary in size – those produced early in the summer often being much smaller than those seen in late summer. They are in the size range of 12-18mm in most species but worker hornets are 20-30mm. Males are about 18mm for most species but in hornets are 25mm.

Distribution

Social wasps occur throughout Britain. The most common and widespread species are the common wasp, Vespula vulgaris, and the german wasp, V. germanica.

Status

There are nine species of social wasp in Britain, including the hornet. One species, Vespula austriaca, is a cuckoo wasp that takes over the nest of another species, Vespula rufa, killing the rufa queen and using her workers to care for the austriaca larvae. Two species of tree wasp, Dolichovespula media and D. saxonica are continental species that have become widespread in Britain since the 1980s.

Habitat preference

Gardens, hedgerows, woodland, grassland.

Where to find them in the garden

Some species, such as Vespula vulgaris, V. germanica and V. rufa nest underground, often taking over an old mouse hole. Vespula vulgaris, V. germanica and the hornet also nest in roof spaces, garden sheds and other dark cavities. They sometimes nest in bird nest boxes, with the wasp nest completely covering the bird box as the wasp nest expands in size in late summer. The four British tree wasps (Dolichovespula spp.) make their nests in exposed positions amongst the branches of trees and shrubs, or on the outside of buildings.

Young queens produced in late summer mate and then seek sheltered places to overwinter. This may be inside buildings, under loose bark or in dense evergreens, such as conifer hedges or ivy-clad trees.

Role in the garden

Wasps and hornets feed their larvae on other insects and carrion that is collected by the workers. During early summer, wasps can be useful predators as some of the insects they collect will be garden pests. Later in the summer, wasps develop a taste for sweet substances, when they can become a nuisance at picnics and on ripening fruit.