Mosquito numbers have people buzzing in some part of the province

·5 min read
Mosquito larva under a microscope.  (Submitted by Laura Ferguson - image credit)
Mosquito larva under a microscope. (Submitted by Laura Ferguson - image credit)

Ross Wetmore can't recall ever being bitten by a mosquito in downtown Fredericton — until this year.

Wetmore owns Wetmore's Landscaping so he's always outside. He notices mosquitos.

"We're in mosquito central here," said Wetmore. "And we notice how bad they are when they get really bad. Normally they're just bad. This year they're really bad."

He estimates there are 30 to 40 per cent more mosquitoes this year than usual.

University of New Brunswick biology professor Steve Heard said Fredericton has experienced "a mosquito explosion" in recent days.

"But we see such booms every year, and because we don't do formal mosquito population surveys in Fredericton, I can't say whether this is a bad year," said Heard.

Submitted by Kate Hawkins
Submitted by Kate Hawkins

"Mosquito populations rise and fall, so a bad May doesn't mean a bad June necessarily."

A lot depends on recent conditions, particularly precipitation and the availability of pools of water, since mosquito larvae grow exclusively in standing water — like ponds, puddles or receptacles around one's property.

"So when it's wet and these things fill up, a few weeks later we have adults looking for their blood meals," said Heard.

And if things dry up, mosquito numbers will drop a "few weeks later" because "it takes one to three weeks for the larval part of the life cycle to complete," he said. "Adults live anywhere from a day or two to perhaps a week."

Laura Ferguson is an eco-immunologist who studies mosquitoes at Acadia University. She said it's actually early for mosquitoes season, since numbers usually peak in July and August.

Ferguson said New Brunswick has more than two dozen species of mosquitoes, and not all of them are fans of human blood. Some, for example, only feed on birds, others only on amphibians.

Submitted by Laura Ferguson
Submitted by Laura Ferguson

Some of those that peak early, however, happen to be the biggest fans of human blood. And those that breed in marshes — like aedes vexans, an inland floodwater mosquito, for example — tend to be more aggressive feeders.

"They're just aggressive and … if they smell your carbon dioxide, they're going to come after you," said Ferguson.

Humans are an easy target, she said. There are a lot of us, and we're not covered in thick hide or fur like some animals.

And it's only the female mosquitoes that bite. They're looking for a blood meal in order to produce eggs.

Ferguson said it's not because we have the best blood. One study she read revealed that mosquitoes were able to produce more eggs with the blood of other animals than with humans.

"So our blood isn't the ideal blood, but … we're accessible. We're an easy blood meal."

Submitted by Laura Ferguson
Submitted by Laura Ferguson

Ferguson, along with a graduate student from Acadia University, has resumed monitoring mosquitoes in Nova Scotia, mostly to keep track of invasive species.

She said mosquitoes numbers can vary between regions, based on rainfall and habitat.

"It does definitely depend on rainfall, because they require water to lay their babies. … Those juvenile larvae, they have to live in water. And so if there's no water around to live in, then you're not going to see any biting adults around either."

While some species proliferate in marshy areas, others prefer containers that humans leave around. They're not fussy, said Ferguson, and will lay their eggs in anything that holds water, including old tires.

Some species only reproduce once a year, but most are a lot more prolific. So that means an early spike in populations could lead to exponential growth.

Submitted by Laura Ferguson
Submitted by Laura Ferguson

"So if you've got lots of babies in the spring, then you've got lots of adults that are going to make lots more babies," she said. "So as long as the conditions remain mosquito-friendly — warm and moist — then yeah, certainly a big boost in the spring could certainly set us up for a summer full of mosquitoes."

But all it takes is some dry weather to negatively impact numbers.

"Because if they don't have water, they can't lay their eggs and their babies can't grow up and become new biting adults," said Ferguson.

The downside — for humans, that is — is that mosquito eggs are quite good at surviving dry conditions, she said. So once the rain arrives, it's "game on" again for the mosquitoes' life cycle.

Life cycle of a mosquito

The mosquito's life cycle has four stages.

First the egg and then the larva, which both occur in standing water such as puddles, ponds, buckets and bird baths.

Then there's the pupa stage, which is considered the resting and non-feeding stage of development, when mosquitoes are in the process of changing into an adult.

Mosquitoes then evolve into the adult phase. That's when females fly around looking for blood meals to start the whole cycle again.

Submitted by Laura Ferguson
Submitted by Laura Ferguson

If you want to avoid bites, Heard suggests timing your outdoor activities "when it's breezy, avoid dawn and dusk and wear long sleeves.

The best insect repellents are those that contain DEET. They are effective, long-lasting, and the safety of that chemical has been studied very extensively."

He also suggests that there may be a "silver lining in a cloud of mosquitoes."

Since mosquitoes support animals further up the food chain, such as bats and some bird species that have been in decline, large numbers of these blood-thirsty insects are actually a good sign.

Our goal is to create a safe and engaging place for users to connect over interests and passions. In order to improve our community experience, we are temporarily suspending article commenting