Why are mosquitoes so bad in 2023?

Mosquitoes.

They’re thirsty bloodsuckers that annoy those who cross into nature, feasting on their salty life source while leaving behind red, itchy bumps.

And this year across Canada, it seems the pesky insects are worse than ever.

Those who’ve wondered about an increase in mosquitoes may be right, according to Laura Ferguson, assistant professor of biology at Acadia University in Nova Scotia.

“It’s definitely been a trend to some extent that people are noticing anecdotally,” she told CTVNews.ca in an interview on Friday. “New Brunswick, in particular, over the last couple of years, has noticed big bursts in mosquito populations, especially in this mid- to late spring.”

Why mosquitoes may be worse than normal in some areas has more than one answer.

WHY MOSQUITOES ARE SO BAD THIS YEAR

Ferguson works with a team to study mosquitoes, understand the different species and track their abundance across North America.

“It’s for a few different reasons why we’re seeing more mosquitoes than we may have at least in the past couple of decades or so,” she said.

The first contributing reason is that there are more species of mosquitoes than in years past.

Different species travel with human goods across the world. They then breed in their new homes, creating populations of specific types of mosquitoes where they’d never existed before.

“Here in Nova Scotia for instance, we didn’t have a (species) a couple of decades ago — it came over from Japan in tire, we think — and it’s just exploded across the province and you can find it anywhere now,” Ferguson said.

Additionally, Ferguson said, warmer winters caused by climate change allow mosquitoes that would die off in the winter to survive and continue reproducing.

Along with being able to survive the milder weather, some types of mosquitoes are able to reproducer faster in warm temperatures because of the type of insect they are. Ferguson says mosquitoes are ectotherms, meaning their regulation of body temperature depends on external sources like the sun.

Precipitation also plays a factor in how well mosquitoes can survive, because they lay eggs in stagnant water.

Ferguson said if it’s a particularly dry spring there may be fewer mosquitoes around, depending on the species. Others lay eggs in the fall, so there would only be a large drop in mosquitoes if the previous year was dry.

Another theory that needs more research, Ferguson said, is the waning effects of the chemical Dichlorodiphenyltrichloroethane (DDT), which was used in the past to control insects in crops, but was phased out in the 1970s due to its harm on other species.

Despite this, the chemical can still be found in water and is circulating in ecosystems.

“Those kinds of holdover effects from these really persistent insecticides may have also suppressed mosquito populations for a few decades,” she said. “And now we’re experiencing a bit of this rebound of these populations as these insecticides and their effects start to wear away in the environment.”

WHAT CAN BE DONE ABOUT MOSQUITOES?

Unfortunately, all these factors lead to an increase in mosquitoes, a problem without fast solutions.

“I think for the most part, what we need to do is just figure out the ways to protect ourselves from contact with mosquitoes because they are a part of the ecosystem,” Ferguson said.

“On a regular basis it’s going to be things like hanging out in a screened porch instead of right outside, making sure that you dump standing water anywhere in your yard.”

Using repellents like DEET and some natural oils can help when out in the woods, Ferguson said.

“Wear light colours, long sleeves, those kinds of things to reduce the area of your body that’s exposed to potential bites,” Ferguson said. “That kind of thing is sort of our best bet of that trying to sort of prevent our contact with them as much as possible.”

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