Wasps have a bad reputation for spoiling summer picnics by landing on, and eating, sugary foods, while also harming us with their painful stings. However, by learning more about wasps and their intricate lifecycles, we might be more welcoming of them in the garden.
What is a wasp?
There are 7000 species of wasp in the UK. Closely related to bees, wasps are carnivorous rather than vegetarian. Like bees, most wasps are classed as 'solitary', meaning the females mate and then make a small nest in which they lay eggs in individual cells stocked with food, before dying (the female never meets her young). If you have a bee hotel you will be familiar with solitary bees such as the red mason bee (Osmia bicornis) and leafcutter bees (Megachile spp).
Solitary wasps have a similar lifecycle, but rather than stocking their nest cells with pollen and nectar, they stock them with insects, grubs and spiders – indeed, some solitary wasps may even use bee hotels. They are extremely unlikely to sting you and therefore pose no threat to you, your children or your pets.
Like bees, some wasp species are 'social', meaning they form large nests headed by a queen and consist mainly of sterile female workers. The queen stays in the nest laying eggs, and the workers gather insect food – typically caterpillars, aphids and other 'pests' to feed the grubs back in the nest. In return for food, the grubs secrete a sugary solution which the worker wasps drink. It's these social wasps that we notice in summer, usually when they start behaving badly.
Unlike solitary wasps, social wasps will sting, especially if they perceive a threat to the nest, for example if you get to close to it. Another sure-fire way to be stung by a wasp is to kill one. When you kill or threaten a wasp, it releases pheromones that other wasps will respond to, and these wasps could then attack and sting you. You should therefore avoid killing or harming a wasp at all costs.
Do wasps do any good?
Wasps are an incredible natural source of pest control. From April to September, they scour garden plants and trees for caterpillars, aphids and other insects to take back to the nest. Wasps are very strong and you may be lucky enough to see one flying while carrying a caterpillar in its mandibles.
Some solitary wasps specialise in a certain species of caterpillar or spider, and 'stock' their nests with insects, which they have paralysed (but not killed), so they are fresh to eat when the caterpillars hatch from their eggs.
If we didn't have wasps visiting our gardens there would be huge numbers of insect pests to deal with. Wasps therefore provide a valuable service to gardeners – without them we would have much smaller vegetable harvests, and many more damaged ornamental plants.
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Wasps also pollinate flowers – some species have a particular relationship with specific flowers, for example figworts and angelica.
Why are wasps so annoying?
It's only a few of the 7,000 species that irritate us in summer, typically workers of the German wasp (Vespula germanica) and common wasp (Vespula vulgaris). Social wasp nests are annual – the queen founds the nest in spring and stops laying in autumn, when the nest gradually dies down as the workers die, and there are no new grubs to replace them.
This means existing workers are suddenly redundant: until that point they spent all their time gathering insect food to feed the grubs, in exchange for a sugary reward. But with no new grubs to feed, they no longer have a job to do, and no longer get the reward.
This is when wasps start to become annoying. Most people don't realise that wasps are active from April, as they cause no problems for us throughout summer, and are actually providing us with a valuable service. However, from August, when the queen stops laying eggs in the nest and the wasps have their supply of sugar turned off, they seek out alternatives.
These can include jam sandwiches, cans of fizzy drinks, beer and ice cream, all the things we like to eat and drink outside, in summer. Wasps can also turn to fruit crops such as grapes, fig trees and pears. Sometimes, by autumn, they turn to windfall fruit or fruit left on trees, which has fermented and become alcoholic.
This can make the sugar-addicted wasps drunk, and behave even more badly. If you're quietly going about your business having a late summer barbecue and you're stung by a wasp, it could be drunk on fermented fruit.
How to get rid of wasps
Now you've understood the lifecycle of wasps, you may look on them more favourably and decide not to try to kill them. In summer, you could try giving them a sacrificial sugary treat, such as a half-empty jar of jam, which should keep them occupied while you eat your food. Avoid placing the jar near where you are eating and there's a good chance the wasps will stay away from you, preferring to eat the jam, instead. Other ways of deterring wasps, include:
1. Avoid leaving barbecues unattended
Barbecues, along with unattended pet food, can attract wasps, which will take the meat back to the nest to feed the grubs
2. Avoid wearing perfume in the garden
Perfume is said to attract wasps
3. Hang a dummy wasp nest
As wasps are territorial, if they think an active nest is in your garden, they will avoid it
Some gardeners make sugary 'baits' to lure wasps to their fate. These can include a lidded jar of jam with water added to it, with holes punched in the lid. The wasps enter the jar through the holes but are unable to escape and then drown in the watery jam. This is unnecessary – by leaving an unlidded jar of jam out the wasps will happily munch on the jam and not pester you. You'll be able to enjoy your meal without having lots of dead wasps on your conscience.
How to remove a wasps nest
If wasps are nesting in your home or your garden, you may consider removing the nest to protect you and your family. Bear in mind, however, that most nests are found in late summer, by which time the queen has already stopped laying eggs and the nest is already dying down naturally. As they've gone unnoticed since the nest was founded in spring, could you tolerate them for just a few weeks more?
It's also worth noting that many 'wasp' nests are actually the nests of bees. Some species of solitary bee nest in walls, while bumblebees may nest in the ground, in long grass, beneath your shed or even in a bird box. Like wasps, bumblebee and solitary bee nests are annual, plus the nests are much smaller and shorter-lived. Although both bees and wasps are essential pollinators, most people would rather not harm bees, so nests should be tolerated if at all possible.
If you are determined to remove a wasps' nest then it's best to get in the professionals. Wasps will attack you if they feel threatened and it can be unsafe to try removing the nest yourself. Call the professionals who will provide a positive identification on the wasps and remove the nest safely. Bear in mind that pest controllers use insecticide to kill wasps, which could harm other wildlife in your garden, and can remain in the soil for many months after it has been applied.