The wasp factory?

>> Fears of a surge in the population
are (probably) much exaggerated

NOT A PLAGUE: Wasps

by PATRICK LEJTENYI

Like the population of the Vespidae family, media stories about a resurgent wasp population appear in frighteningly heightened numbers in late summer. Reports about ruined picnics, terror-filled nights on the terrasse and agonizing stings in unusual places make the regular rounds. La Presse ran a story last Thursday about the wasp effect on bar owners’ bottom line. French-language radio stations picked up on the story the same day, with interviews with the same pest controller airing on at least two stations. The Gazette followed suit on Sunday, mentioning their diet preference and tips on how to build your own wasp catcher.

And while few, with the exception of the pest controller, would declare there is an all-out explosion of wasps this year, their numbers and daring do make them more noticeable to the average fearful human. The population (non-) boom has more to do with people’s short memories than with any real insect plague, say two experts contacted by the Mirror.

“I’ve heard this so many times from people in Montreal,” sighs Jacques Régnière, a research scientist with the Canadian Forest Service based in Quebec City. Our (comparatively) warmer, longer springs and summers result in a higher wasp population here than in parts north come fall, he says, but it’s generally impossible to assert whether there is a sustained boost to the number of, according to last week’s ever-pithy U.K. Daily Mail, “drunk, foul-tempered and sex-mad” wasps.

“They’re just really visible right now,” says Christopher Buddle, an assistant professor of forest insect ecology at McGill’s Macdonald campus. “It’s very difficult to tell. It depends on a lot of factors. The colony size is at its maximum now, and it’s producing workers. And they like the same things we do.”

But despite their bad press, wasps aren’t the pests of lore. Yes, late-season wasps tend to swarm around sugary beer bottles and fruits in August and September, but in the earlier parts of the summer, they feast on insects and leaf-munching caterpillars, bringing protein to larvae in the nest and helping the colony grow. “They really keep things in check,” says Régnière.

What can be alarming to hapless outdoor eaters, however, is a primitive communication system that drones share when a food source is nearby.

“There are airborne cues, pheromones, to help them find their way back to the colony and help them forage,” says Buddle. Pheromones also help wasps defend the colony when under attack, and, unlike cuddly bumblebees, wasps can sting repeatedly.

Both Régnière and Buddle say that while it is impossible to determine any upswing in the wasp population, several factors do affect numbers. Régnière says that, because wasps are cold-blooded, “The colony’s growth rate is temperature dependent.” Mild winters, for instance, might result in more wasps in late summer, but on the other hand, a damp spring increases the risks of insect pathogens that could wipe out a colony.

Buddle won’t commit either. “There are too many ifs. Everyone says it could be the mild winter, but the thing with wasps is, the queen over-winters [meaning she lies dormant and impregnated, ready to lay eggs in the spring]. So maybe [a population boom] has something to do with global warming, but… well, I’m not a betting man.”