Before tackling the issue of getting rid of wasps, I will cover some of the background features of wasps and what good they can possibly do?
The life cycle of a wasp nest colony is indeed a cycle so let us start at the ‘beginning’ with a fertilised queen wasp coming out of hibernation in around early to late April. The queen will emerge from the hibernation spot, typically under the bark of a tree, or other crevice. I have occasionally found a hibernating queen in the folds of a stored horse rug!
This solitary queen will build an initial nursery nest, about the size of a golf ball, in a sheltered location such as under a lean too roof, a garden shed or under a branch in bushes. She will then lay eggs inside this nursery nest to produce the first workers, typically 10 – 20 eggs initially. The subsequent larvae are cared for by the queen until their emergence as an adult wasp. These initial workers will then take over the building and expansion of the nest and foraging for food to feed the queen, who will then remain in the nest to be solely a producer of new eggs.
The nest will then undergo a period of rapid expansion, with the queen producing 200 – 300 eggs per day. Each worker wasp lives for around 2 – 3 weeks, so with the rate of succession of new wasps, a typical nest can have around 5000 wasps at one time!
After the climax of nest expansion, around mid to late summer, the rate of nest expansion slows, and the population growth stops. The queen will then produce new queen cells and lay several queen larvae. The queen will later die or become sick. Without the role of looking after the queen wasp, colony adhesion will break down and cannibalism sets in. Foraging becomes more erratic and they become more of a nuisance around pub gardens and BBQs! Virgin queens will leave the nest, mate, and hibernate in the same way the initial nest instigator did the previous autumn.
Many hibernating queens will be killed over winter by spiders as they share similar crevices. Warm winters will also cause the death of many queens as they will emerge from hibernation before plants are flowering and providing pollen and before other small prey insects are in abundance. Overwintering queens will usually emerge from hibernation when temperatures in the shade reach around 10 degrees centigrade.
Wasp nests are only single use and so wasps do not return to use the same nest the following year.
The nest is made from wood fibres which the worker wasps have chewed with their mouth parts and carried back to the nest. The wavy pattern of the nest surface is the result of different wood sources being used.
Nests are built in holes in the ground, crevices in walls, or are constructed as free hanging nests in bushes, or hanging from eaves and joists. 77% of Vespula vulgaris and 91% of Vespula germanica build their nests underground, indicating how wasps in the UK actually prefer to nest in the ground and away from human structures.
Wasps do not attack without provocation. I have heard it said that the reason they like to fly around our faces is that they are curious and simply want to have a look! The ‘good’ points about wasps that people often question is their ability to feed on aphids, caterpillars and other pests of garden plants. They also feed on dead carrion so the play a role in the decay of matter and are also a good food source for many birds.
How to get rid of wasps? A common amateur attempt is to pour petrol onto a nest and set light to it. This may eliminate a nest hanging in a bush, but it may also eliminate the bush. Lighting petrol into a nest in the ground will only scorch the surrounding grass. Products are available in hardware shops for amateur use and are very effective for those brave enough to attempt it. Wasp ‘pots’ are available which contain a liquid attractant in which wasps will drown once they have found their way into the pot. A home made version can be fashioned using a jam jar, half filled with attractant such as coke or watered down jam, with a hole in the lid. Don’t be dismayed when the occasional wasp finds its way out of a wasp pot as it will go back to the nest to let other wasps know about the delicious attractant you have kindly left out for them. No kidding, they really will have the community cohesion to let each other know where potential food sources are.
Bear in mind that when stressed or crushed, wasps emit several distress chemicals which will alert other wasps to attack so try to resist the temptation to squash individual wasps.