As summer winds down and Canadians try to soak up the last warm days with outdoor picnics and barbecues, there’s an unwelcome guest that seems to be everywhere: wasps.
These buzzing insects are out in full force, swarming food, stinging unsuspecting victims and turning peaceful garden gatherings into frantic swatting sessions. This surge in wasp activity, a common late-summer phenomenon, may leave some wondering why these critters are particularly aggressive right now and what, if anything, can be done to keep them at bay.
“This does happen at the end of every season, when the wasps’ nests are at their peak,” explained Nathaniel Heppell, owner of Ace Humane Wildlife Removal and Pest Control in Oakville, Ont.
“But they’ve been fairly sizable this year. I’ve been quite surprised with the mass population inside some of these colonies. That’s something significant that was different from last year. The population in these colonies is greater than I’m used to seeing,” he told Global News.
Wasps become more aggressive in late summer and early fall because their colony dynamics change significantly, Heppell said. The wasps most often seen buzzing around food during this time are yellow jackets, which are currently causing the most trouble for people.
Several thousand people are stung by these venomous insects each year, according to Health Canada. In rare cases, severe allergic reactions to the venom can be fatal. The agency advises seeking immediate medical attention if a sting causes unusual swelling, itching, dizziness, or shortness of breath.
Despite being a nuisance, wasps are also beneficial in many ways. Worker wasps catch insects like flies and caterpillars to feed their developing larvae, helping to control pest populations. They also act as pollinators when they visit flowers for nectar.
And it’s perfectly normal for them to be extra pesky at this time of year, Heppell said.
“Yellow jackets don’t make honey, but yellow jackets produce larvae — we call them grubs that look like little maggots — but they’re just baby yellow jackets. And it’s those workers’ jobs to bring those insect fragments to those babies. And they feed them,” he said.
And when the wasp feeds its grubs, they release a sweet substance called larval secretion, which serves as a sugary reward for the worker wasps. This encourages the workers to continue hunting for food to bring back to the nest. It’s an exchange of food between the two.
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“So when these queens stop producing larvae at the end of the season when the nights get cooler, she’s ready to terminate the breeding that happens inside the colony. That means that all those workers, all those hundreds of workers in a colony, are out of a job and out of a food source. So they’re coming after you,” Heppell said.
Although this is part of the normal seasonal pattern for wasps, experts like Heppell say there seem to be more wasps than usual this year.
The wasp problem isn’t confined to Ontario. Prairie provinces have also experienced a significant increase in wasp activity this year.
In Calgary, Antoine Ouellette, owner of That Pest Control Guy, told Global News on Aug. 20, said the phone lines have been buzzing with wasp activity this season.
“It’s so busy, it’s incredible. We have at least 30 calls a day,” he said.
The increased activity is attributed to the warm weather and plentiful food sources, creating ideal conditions for wasps to thrive. One of those food sources is aphids, according to Ouellette. Aphids are small insects that feed on plant sap, and wasps like them because they provide a food source for their larvae.
“The more there are aphids the more there are food sources, and it is normal to have more wasps,” Ouellette explained.
Another reason adding to the population wasp boom is the mild winters some Canadian provinces had, Heppell said.
The mild winters, such as the one Ontario experienced this year, make it easier for these species to overwinter, resulting in less die-off and more yellow jackets in the spring.
Lincoln Poulin, president of Poulin’s Pest Control in Winnipeg, noted the high wasp activity this year and advises exercising caution if you spot a wasp nest on your lawn.
People may notice hanging nests on trees and other places. If the nest is visible and hanging from a tree, he said it’s relatively easy to use insecticide spray to treat it, knock it down and remove it.
However, it’s particularly important to be cautious of nests built in cracks in houses and other crevices on lawns — also known as hidden nests.
“When people discover a wasp nest, I always recommend that they leave it to the professionals. I can tell some horror stories that I have witnessed when people try doing it themselves,” Poulin said.
Many people try to use expandable foam or silicone to seal off openings with wasps inside, but he warned against this method. This is because the wasps will likely end up inside the house, finding another way out and potentially creating more problems.
To avoid getting stung by wasps during an outdoor gathering, he recommended using a fan on the deck or in an open space, as wasps dislike them.
“The other option is wasp traps. Very effective. Wasp traps are designed to attract a wasp to where you want it, so maybe at the edge of the deck or the fence line, and it’s not going to catch them all, but it catches a significant number to prevent them from going to where you’re at.”
— with files from Global News’ Joelle Tomlinson
