Wasps and Hornets

Wasps

Social wasps are common in British gardens.

There are several species of wasp. The common wasp has a sharp tapered abdomen and black and yellow stripes. The hornet is the largest British wasp. All wasps have a reputation for stinging, however, the needle-like sting is possessed only by females and is concealed near the tip of the abdomen.

Queen wasps hibernate over-winter and emerge to build a nest in the spring. The nest is usually located in the ground or in cavities in trees, walls or buildings. Wasps frequently nest in the roof space of houses. The nest is built up from wood pulp, which is moulded into the outer shell of the nest and many internal chambers.

The queen lays an egg in each of the chambers, which hatch into larvae. When fully grown the larvae pupate and emerge as workers (or drones) who assist in rearing new larvae and new queens. Towards the end of the summer the queen lays a number of eggs which produce male wasps that mate with the new queens. In autumn all wasps die with the exception of the new queens that hibernate then emerge to build new nests the following spring. Old nests are not re-colonised the following year although a new nest may be established next to an existing nest.

Unless a wasp nest poses a particular danger to you or your family they are best left undisturbed. Where necessary, you can treat nests yourself although extreme care should be taken and it is recommended that this is left to a professional with protective clothing. However, if treating yourself, it can be done through the application of insecticidal dust at the entrance to the nest (preferably after dusk when the wasps have returned to the nest and are less active). Wasps will carry the insecticide into the nest, spreading it to other wasps in the colony. Insecticide is available from most DIY stores and garden centres and you should ensure the product you buy is specifically intended for wasps and that you follow the instructions on the package precisely. Treated nests need not be removed.

Foraging wasps can be a nuisance when they turn to food sources such as ripe fruit, sugary drinks, jam or honey. Individuals can be killed using an insecticidal spray designed for flying insects, which are available from chemists, supermarkets, hardware shops, DIY stores and garden centres. Care should be taken when using sprays and the instructions on the package should always be followed.

Wasps can be useful pollinators and are beneficial in catching and killing garden pests (aphids) to feed to their offspring.

Hornets

Hornets are similar to common wasps, but are larger and chestnut-brown and yellow (rather than black and yellow). They are usually found in parks and woodlands but may also be found in domestic gardens.

They also build papery nests, which are usually found hanging from trees or underground, but can also be found in roof spaces, wall cavities, chimneys and building air-grates.

The hornet life cycle is similar to that of the common wasp. Newly-mated queens hibernate during the winter, and emerge in spring to begin building a nest. They lay eggs that hatch into sterile female workers who complete the nest building and collect food for the developing larvae. Later in the summer males and fertile females hatch, mate and the females become next year's queens. The males, old queen and workers die in the autumn. Old nests are not re-colonised the following year.

Both adults and larvae eat mainly insects and may supplement their diet with tree sap and windfall fruit. They also stock up on nectar before hibernating and can become a problem when they forage for sugary foods such as jam, fruit, etc in the late summer.

Hornets, like wasps, only tend to sting if threatened.

Wasp and Hornet Advice

• Do not disturb or interfere with wasp or hornet nests. Seek further advice.
• Old nests are not re-used the following year (although a new nest may be established next to an old nest).
• They will sting when threatened or disturbed.
• Don't panic and wave your arms wildly in the presence of wasps or hornets. Try to stand quietly and once they discover you are neither food nor flower they should move away.
• If you react badly to wasp, hornet or bee stings, seek immediate medical advice.
• Wasps and hornets do not swarm - only honeybees swarm.

Pest Control

Elmbridge Borough Council does provide a pest control service for the treatment of wasp nests but does not treat bees.

If you would like to use our pest control service visit our |pest control webpage where you can contact us to arrange an appointment.

Further information

• |Wasp advice leaflet
• |Bees