Wasps — they’re hard to miss if you spend any amount of time outside, and as we enter the latter half of summer these aggressive and disruptive insects become an increasingly common annoyance.
We spoke with Graham Parsons, Pollinator Biosecurity Specialist for Saskatchewan Agriculture, to learn more about what drives their behaviour, the role they play in the ecosystem, and what can be done to prevent them from disrupting outdoor activities.
Parsons explained why wasps appear to be more common during this time of year.
“The main thing is just forage resources, forage meaning food for the wasp. Most wasps are predators, they’re eating other insects, and then they’re also pollinators,” said Parsons.
The adult wasps gather protein sources (mainly from other insects) and feed it to their larvae, and while adults need protein too, they primarily forage for carbohydrates. They get these carbohydrates in the form of nectar from flowers.
“Both of those things this time of year come in a little bit shorter supply. The insect populations are kind of on the downward slide and the flower numbers are on the downward slide, they’re producing less nectar because there’s less sunlight and heat,” he explained.
“The flowers are finishing their seasonal blooms for the year, so both of their food sources are coming less and less so they’re poking around our human food sources as they need more stuff to feed themselves.”
As the common food sources for wasps become less available, Parsons explained, wasps are drawn to human activities, such as barbeques and even pet food that may be left outside.
How do you tackle your wasp problem?
Parsons said if you notice an uptick in wasp activity there are some steps that can be taken to eliminate the problem.
“If you can find the nest, a good way to do it is to go out at night, after dark, and take a red flashlight. Wasps and hornets actually don’t see the red colour spectrum very well and you’re able to see it reasonably well,” said Parsons.
“Take a can of Raid spray or something like that, there’s some that will shoot quite a distance, so you can spray the nest and get rid of it that way.”
He also suggests that while wearing adequate protection, covering the nest with a bag and removing it by twisting the nest into the bag can also work.
Parsons explained that while methods that capitalize on the territorial nature of wasps — such as decoy nests — could garner some positive results but using them this late in the season is less effective as the nests are established.
He suggested placing potential food items or traps in an out of the way portion of the property can help alleviate the problem.
It may be difficult to locate the nest(s) in question, so Parsons outlined some of the more common places where they can be found.
“A common thing for bees and wasps is a space between old buildings and granaries, a hollow cavity of some kind where they’ve got protection from the weather,” he said.
“Overhanging parts under decks are a really common spot because it’s nice and relatively dry and out of the way.”
He notes that wasps will also set up shop in small crevices that lead to a space around the size of a softball. He recommends filling these spots with spray foam or something their mandibles cannot cut through like steel wool.
“If you’ve got lots of tree cover around, go and take a poke around. That’s a little tougher to do because you can’t see them (as easily). There are lots of trees, branches and sticks in the way. Unless you can see them flying in that direction, it’s a little bit tricky.”
What role do wasps play in the ecosystem?
While wasps are a rather common pest, doubly so as they encroach into human spaces, Parsons explained the crucial role they play in the larger ecosystem.
“They’re very effective predators of other insects, pest insects, particularly some of the caterpillars and flies and different pest organisms,” he said.
“People hate getting stung and harassed by wasps, (but) because they are feeding their larvae insect meat, they actually eat a lot of insects that would be pests otherwise.”
He added that due to their foraging habits, wasps also serve as pollinators for numerous plant species, albeit not as effectively as other pollinators such as bees.
Although protecting pollinating insects has been a common topic of discussion in recent years, he noted people should not be hesitant about removing a troublesome nest.
“Don’t feel bad about getting rid of a nest here or there. They’re very common, they’re very widespread. You’re not going to diminish their population or anything,” said Parsons.
“If it’s a safety concern, don’t feel bad about getting rid of the colonies, they’ll bounce back next year. There are going to be some other wasps or hornets to pick up their spot.”