NATURE’S ARMY OF STRIPED HELPERS
Considered a nuisance when gatecrashing picnics, the Common wasp plays an important role by feeding on crop-harming pests
IT IS A hot, muggy summer day, and with a high-pressure system poised over the country, the weather is likely to stay fine for the next few days: perfect for picnics and barbecues.
With birdsong now more or less over for the season, insects are the main summer soundtrack. Bumblebees buzz purposefully along the edges of fields in search of nectar; grasshoppers and crickets chirp their high-pitched songs from the long grass; and Meadow Brown and Gatekeeper butterflies are on the wing.
But another, less welcome, yet no less important, insect is also out and about: the Common wasp, Vespula vulgaris. As the sun rises in the clear blue July sky, they emerge from their nest and begin to forage for food. And suddenly, outdoor dining does not seem such a good idea after all.
Wasps are attracted to sweetness, and cakes, fizzy drinks, relishes and ketchup all act as a magnet for these striped creatures. They have a very acute sense of smell and can detect sugars, whether natural, such as nectar, or man-made, as with our food and drink, and then home in on the source.
Thousands of wasps
There is not just one kind of ‘wasp’: there are more than 7,000 different species living in the UK alone, which is more than there are species of mammal on the planet, and there are more than 100,000 species of wasp worldwide. The definition of a ‘wasp’ is, however, rather vague: any insect in the order Hymenoptera that is neither a bee nor an ant.
Britain’s wasps range from tiny creatures, just a few millimetres long, to the hornet, which can reach a length of more than 1in (28mm). Globally, the largest wasp is the Asian Giant hornet, Vespa mandarinia, with a length of more than 2in (5cm), although another species, the Giant Scoliid wasp of Indonesia,
“Lord, clear my misted sight that I May hence view Thy divinity, Some sparks whereof thou up dost hasp Within this little downy wasp”
Edward Taylor, ‘Upon a Wasp Chilled with Cold’
Megascolia procer, boasts a wingspan of 4¾in (12cm).
While some species, including the Common wasp, do sport the classic striped appearance, other members of the family do not look like wasps at all. Just to confuse matters, many other species, such as hoverflies, mimic the coloration and behaviour of wasps. This protects them from predators, which will not attack a wasp because of its sting.
The Common wasp, of the genus Vespa, is a medium-sized insect, with adults ranging in length from ½-¾in (13-19mm); females are slightly larger than males, to enable them to carry their eggs. The head and face have a distinctive pattern, with striking patches of yellow and black. The thorax is dark, with small yellow patches; the abdomen alternately striped in yellow and brownish-black, and the wings are clear, with black filaments. At the wasp’s ‘tail’, which is actually the end of its abdomen, is the dreaded sting. But this is only present on female wasps; the smaller males lack the ability to sting.
Wasps have highly developed sight. Like most other insect species, they have compound eyes on the sides of their head, giving them excellent peripheral vision. They also have very well-developed senses of smell and taste: a key advantage when locating new sources of food or finding their way back to known ones.
Common wasps are fast fliers. They are on the wing from March to the middle of November, and earlier or later in very mild weather, and will be active as soon as there is enough warmth for them to fly.
Feeding habits
Diet-wise, adult wasps feed on nectar from flowers and sugar from rotting fruits, but they feed their young on animal prey, such as caterpillars, which they kill with a single injection of their sting before bringing them back to their nest. The sting contains a complex venom powerful enough to paralyse the unfortunate victim. Unlike that of the honeybee, whose venom is acidic, the wasp’s alkaline venom does not cause the insect’s own death when the prey is stung, so can be used again and again.
Common wasps are among the most adaptable of all Britain’s insects. They can live in a wide range of semi-natural and man-made habitats, including grasslands, woods and forests, and, of course, parks and gardens in towns and cities, as well as the wider countryside.
Because of their adaptability, unlike many more specialised insects, they continue to thrive. However, wasps are susceptible to sudden fluctuations in the weather; especially unseasonably cold spells in spring, when the queens may be tempted to come out of hibernation too early. If it then turns cold again, as happened in 2012, they often die because of a lack of food. Conversely, hot, dry and settled summer weather allows wasp populations to boom, as they are able to hunt all day long.
Nest fit for a queen
This is a social species, nesting in large colonies made up of a queen and as many as 10,000 other individuals by the end of the summer, although a more typical colony holds between 3,000 and 6,000 wasps. Nests may be in a hollow of a tree, a cavity in a rock or inside a building, such as the roof space of a shed.
The nest is built initially by the queen, which emerges in spring to look for a suitable site. To start off the nest, she collects wood pulp, which she chews off and mixes with her saliva to build individual hexagonal cells, into each of which she lays a single egg. Together, the cells form the shape of a honeycomb.
Once these eggs hatch, she rears the larvae as her first cohort of sterile female
workers, which will then build the rest of the structure.
From now on, the queen becomes an egg-laying machine, losing her ability to fly, and may lay as many as 200-300 eggs a day. The larvae are fed by the workers, which forage for smaller insects, which they sting and bring back to the nest.
Some of her offspring will become daughter queens, and once she has produced those, her job is complete and the original queen will die. Eventually, her daughters leave the nest, mate with the males and spend the winter in hibernation before they, too, emerge in the spring to start their own colony. They spend the winter in any safe, sheltered place, such as a hole or cavity in a tree or the interior of a building. They will emerge on a warm,
sunny day the following spring, although if the weather turns cold, they will go back into temporary hibernation, in the same way other insects do.
Valuable pollinators
People often ask why wasps exist, in the mistaken belief that they serve no useful purpose. Yet, without them, the balance of nature would be put severely out of kilter, as they feed on many other smaller insects and other invertebrates, including many pest species injurious to crops. They are also important pollinators, although the credit for this is usually given to bees.
We tend to notice wasps more in late summer, partly because they are around in greater numbers than at other times of year. The warm weather also means we are outside more, often consuming those sweet and sugary foods and drinks which prove a major attraction to wasps.
One reason why people are stung by these insects is because they panic, flapping their arms at the wasp, or trying to kill it, while breathing heavily, which tends to attract them. Swatting a wasp is an even worse idea: when injured or killed, these insects release pheromones to attract other wasps, which will then attack.
The best way to avoid being stung is to sit quietly and avoid sudden movements and heavy breathing. It is sensible to take such precautions: some people are allergic to wasp stings, and, in very rare cases, the sting may cause anaphylactic shock and even death.
Wasps have few predators, the best known being the Honey buzzard: a very unusual bird of prey which digs out wasps’ nests to feed on the juicy larvae. Great tits are able to remove the sting before eating the insect, and according to naturalist Brett Westwood, one old folk name for the Great tit was ‘bee-biter’.
But because wasps feed on so many insect pests, and also pollinate plants, they are a very valuable insect in their own right. Rather than killing them, we should cherish their presence; even if that means avoiding the consumption of sugary foods and drinks outdoors while we are enjoying a meal in the sun in summer.
“If I be waspish, best beware my sting”
William Shakespeare, The Taming of the Shrew