Spring is when the queen wasp looks for a site for a new nest as she does not use the old nest from a previous year. The queen starts the nest by chewing wood or bark to make a type of papier mache. At this stage, the nest is only the size of a golf ball and may be attached to the branch of a hedge, the ceiling of a porch or a rafter in a loft etc, where she will lay her first 10-20 eggs. The eggs hatch and turn into the familiar black and yellow striped wasps. These wasps forage for food and begin to enlarge the nest. By late summer, the nest may contain 10,000 wasps and be the size of a football. Some nests can be even bigger.
All these wasps are sterile female workers and their job is to attend to the queen, maintain the nest and bring back food for the young wasp grubs. In late summer a few male wasps and new queens are hatched. These mate and produce fertilised queens. As the cold weather approaches, the activity in the nest reduces, the female workers and males die, and only the fertilised queens survive. These queens look for a safe crevice to spend the winter and hibernate. In spring, they emerge to start the life cycle over again.
Unlike bees, wasps do not make honey. Instead the adult wasps feed on sweet substances such as nectar in flowers and on fruit. They also kill large numbers of insects which they take back to the nest to feed the young. At this stage, wasps are a beneficial insect as they are part of nature's control of many insects in the garden. They are also so busy collecting food for their young, that they are not normally a problem. Wasps will however, defend the nest aggressively if it is disturbed or threatened, so you should leave eradication to a pest control technician who has protective clothing and specialised insecticides.
As autumn arrives, the queen stops laying eggs and a large number of wasps find themselves with less and less work to do. It is at this stage that wasps become a nuisance as they search for sweet food and enter buildings looking for jam, sugar, soft fruit etc. This is when they are most likely to sting.
The old nest consists of a fragile papier mache shell and contains only a little debris and the remains of any unhatched eggs. It does not smell or cause any damage. If the nest is outdoors, it will dissolve in the wind and rain. Indoors, the nest will slowly crumble to dust. It is not necessary to remove the old nest. If it has been treated with insecticide and you do want to remove it, wait for at least one week after the treatment.