Why badgers are bad news for wasps

ANOTHER LIFE:THE WASPS come home to their nest a few at a time, converging like unsteady helicopters in an airspace at the corner of my eye. On this side of the glass, I'm trying to watch the evening Proms on telly; beyond it, the entry procession at the crack in the eaves is too wavering and out of tempo even for the slower bits of Shostakovich.

I could, of course, move my chair. And it's a small enough complaint to offer about life with Vespula vulgaris, our common social wasp. I dodge around the solitary queens in early spring, out from hibernation. Sometimes I find one rasping at the weathered grey wood of the shed door and mixing the fibres with spit for the paper to start her nest.

Later, as the queens’ progeny grow into workers, the blossom of the cotoneaster tree is thronged exclusively by wasps, their short tongues tailored to the tiny, shallow flowers. This nectared energy is spent on catching and chopping up other garden insects, many of them not the gardener’s friends. And it’s only in late summer, for reasons I’ll come to, that the wasps head for windfall apples in the orchard and other people’s jam butties at the car park behind the strand.

There must, by now, be a whole line of nests in the roof-space, for each queen starts a new one every year. She does all the early work, suspending a wood-pulp umbrella from the roof of a hole or a beam, moulding a tier of paper cells beneath it, then laying an egg in each. She has to feed the grubs with chewed-up caterpillars and other insects, and it’s five weeks or so before the first brood grow into workers and take over the nest-building and foraging, feeding the grubs with macerated insects and leaving the queen to lay eggs. As the colony grows, each new tier of cells – a comb – is hung beneath the previous one by stalk-like pillars, producing an edifice rather like Dublin’s Central Bank building, only ball-shaped. It hangs within the spherical envelope of paper, leaving space so that air – and wasps – can circulate, entering and leaving through an opening at the bottom.

This is all very well for wasps in house roofs and sheds, but most queens begin with a mousehole or other small cavity in the ground. How does the colony contrive a paper lantern almost the size of a football and containing eight or more tiers of comb? The answer is logical but awesome: the wasps enlarge the hole. They swallow water from a puddle, carry it back to the cavity, spit it out on the wall of the hole, scrape the mud off in pellets and fly out to drop them, sometimes several metres away. They may even push small stones out of the hole. What happens when they meet a big stone, as they certainly would in my garden, I have not learned.

As to the sweet tooth of wasps in late summer . . . Wasps, like ourselves, need carbohydrates for energy. As the workers feed the growing larvae with chewed-up insects, the grubs absorb the protein but dribble out the sugars in saliva, eagerly lapped up by their providers. In late summer, when broods are reared, this supply of carbohydrates dries up and has to be found elsewhere, in fruit or sticky drinks.

One natural sticky drink is the "honeydew" exuded at the anuses of aphids, the sap-sucking scale insects infesting plants and trees. This surplus of sugary goo, dripping on to leaves and twigs, provides a medium for growth of the black mould that often disfigures garden plants beneath trees such as willows and limes. But it also meets the needs of myriad wasps, often in company with butterflies and ants. In New Zealand, indeed, where Vespula vulgarisis an undesirable alien, honeydew from aphids draws wasps in dense numbers to the sap-rich native beech forest, monopolising this sugar supply at the expense of indigenous insects and birds.

A bitter winter and wet summer have both worked this year to reduce Irish populations of flying insects, wasps among them. But what are their living controls? As a letter in today’s Eye on Nature suggests, dragonflies are among the few predatory insects prepared to risk an attack.

But badgers will dig out the ground nests of wasps to feed on grubs and adults, ignoring the stings and scattering earth far and wide. On expert witness from the late Ernest Neal, “badgers account for a great number” of nests. People living in the Irish cattle counties officially cleared of badgers in the cause of reducing bovine TB will thus know who to blame for the buzzing in the kitchen.

Eye on Nature

In a large tree behind my garden, I heard a very distinctive short, loud, tapping sound like something striking hard wood, repeated several times. Each time the tapping began, three or four rooks stormed the tree top, shrieking. The tapping continued for 10 minutes. Was it a woodpecker?

Clara Clark, Blackrock, Co Dublin

It could have been. Great spotted wood- peckers have begun to breed in Wicklow woods and seem likely to spread from there.

I notice some bumblebees sitting on flower heads, not moving then falling to the ground and dying.

Alyson Lysaght, Sandymount, Dublin

Bumblebee deaths are mostly caused by either external or internal parasites which feed on the bee.

During a barbecue, I noticed a dragonfly with a wasp attached to its head. The wasp seemed to be stinging it. We tried to swat the wasp away in vain.

Noel Curtin, Ashbourne, Co Meath

On the contrary, the dragonfly was eating the wasp.

One evening, I saw 21 thrushes picking around on a lawn. Later in the same area I saw about 10 thrushes feeding in low shrubbery. I thought thrushes were getting scarce.

Anne Marie Flanagan, Merrion Rd, Dublin

• Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo. E-mail: viney@ anu.ie. Please include a postal address.