Facts on Wasps
Wasps have a bad image. They sting but not if left alone. In fact they are very beneficial insects with a highly developed social structure.
There are seven species of social wasp in the UK. The commonest is the Common Wasp followed by the German Wasp, both of which nest underground and in cavities in trees, walls and buildings. The Tree Wasp is common and very aggressive and builds its nest in trees and other aerial sites as well as underground. The Norwegian Wasp is less common in the southern half of Britain but is the dominant species in Scotland. It builds its nest among twigs and branches. The Cuckoo Wasp does not have workers of its own and lays its eggs in the nest of another species - the Red Wasp which nests underground. The largest - the Hornet is largely a southern species which nests in hollow trees or in buildings but, with the recent series of mild winters, it is being found much further north.
Life cycle
The fertilised queen emerges from hibernation in the spring and sets about looking for a suitable nest site. For the Common Wasp this is usually a hole in the ground but may be a cavity in the loft or in a garden shed.
She sets about making a basic nest constructed from chewed wood pulp mixed with saliva.
She starts by constructing a single layer or canopy and works outwards until she reaches the edges of the cavity. Beneath that she constructs a stalk to which she attaches several cells in which she lays eggs.
These fertilised eggs will develop into sterile females known as workers.
She initially raises the first few sets of eggs herself until enough workers exist to maintain the offspring and to build the nest without her assistance.
The queen's only job now is to lay more eggs.
By the end of July she will have produced enough workers (may be up to 10,000) for them to completely take over the maintenance of the nest and the feeding of the larvae etc.
Towards the end of the autumn larger cells - known as "Royal Cells" - are constructed and are used to rear the queens that will found next year's colonies (it would appear that whether a larva develops into a worker or a Queen depends to some extent on the amount and type of food given to it). Males are also produced at the same time from unfertilised eggs. These leave the nest, mate and the mated females (future queens), then overwinter to start the cycle again.
Meanwhile, the founder queen, the males and all the workers die and the nest becomes deserted.
Wasps as Pests
Wasps can cause serious damage to soft fruit but ripening apples and pears are unlikely to be affected unless first damaged by birds or caterpillars. Wasps can be a considerable pest in sugar warehouses, jam factories and other sites containing sweet-smelling substances. They are a nuisance in houses where food is being cooked or eaten. They are also a serious pest of hive bees in some seasons. In the spring workers will attack and carry off foraging worker bees while later in the year they will take honey and carry off bee grubs and pupae.
Wasps as Friends
Wasps are extremely beneficial animals. They feed their young on a wide range of invertebrates and in so doing help to control many insect pests. They also visit flowers and therefore help in pollination.