During spring and summer, common wasps (Vespula vulgaris) feed their larvae dissected insects and carrion. In return, the developing young secrete a carbohydrate-rich sugary fluid for the attendant adults to drink – an exchange known as trophallaxis. By early autumn, a single nest can contain up to 10,000 sterile female workers, but just as the population reaches its peak, the queen stops laying eggs and the number of larvae rapidly declines, sending the colony out in search of alternative sources of sustenance. So, despite their reputation for plaguing summer picnics, it’s at this time of year that wasps really make their presence known.
While the larvae are carnivorous, the hourglass-figured adults subsist solely on a liquid diet. At first, they feed on nectar, but as temperatures cool and flowers begin to fade, they turn their attention to other sweet substances. In recent weeks, it’s become impossible to enjoy a pint of cider in the pub’s beer garden without an interloper or two crawling into my glass to sup the dregs. And every time I’ve attempted to gather fermenting windfall fruit from beneath my crab apple and pear trees, I’ve roused a rabble of erratically flying, inebriated insects.
One evening, my neighbours invited me over to see the swarm that had invaded their garden. Their lawn is bisected by the Lavant stream and a horde of striped marauders had massed around an aphid-infested willow tree that overhangs the water. As we approached, I could see that the underlying footbridge was crawling with wasps getting their sugar fix from droplets of honeydew (secreted by aphids) that had spattered the wood.
Realising that my ankles were exposed, I picked my way across the sticky planks with some trepidation. Hangry wasps are easily provoked, and when they sting or are crushed underfoot, alarm pheromones are released in the venom, inciting their sisters to attack. But my fears were unfounded, as the sugar-crazed creatures were so intent on lapping up the sweet excrement that they largely ignored our presence.
These workers and their incumbent queen would soon succumb to the cold or starve to death, so we retreated indoors, leaving them to savour their last hurrah.
• Country Diary is on Twitter at @gdncountrydiary
