Peak season for black legged ticks hits Ontario

You may think the end of summer heralds the ends of tick season, but one expert says that's "definitely a myth" she'd like to break.

In fact, Katie Clow says fall is the prime season for adult black legged ticks — feared for their ability to carry Lyme disease.

"October into November, sometimes in December, if you have a nice warm fall, is peak adult time," explained Clow, an assistant professor in the department of population medicine at the Ontario Veterinary College at the University of Guelph.

That's because the adult black legged tick is "very reliant on humid conditions" and struggles in hot and dry weather during the summer, said Clow.

"If it gets too dry, it can die."

Each kind of tick prefers a different environment, she explained. But because of its draw to humidity, the black legged tick is often found in forested areas, where there's a layer of "leaf litter" on the ground to hid in when they aren't feeding, and a plethora of hosts — like white mice for nymphs and white tailed deer for adults — to attach to.

And although people are more likely to cover up with long sleeves and pants in the fall, Clow said people should still conduct "tick checks" after spending time outdoors.

"Think about sort of the line where our socks meet our pants, or our wrist line, where ticks can crawl up. We don't really feel ticks, unless they're particularly large, they're kind of sneaky that way, " said Clow. "It's really easy for them to go unnoticed." 

"That's why doing a good tick check is important."

Range of black legged tick expanding

Meanwhile, as the temperature warms up, black legged ticks are being found further and further north. 

"We've seen range expansion ... which has been associated with climate change," said Clow.  

A tick needs to feed before growing to the next stage of its life cycle: from larva to nymph, from nymph to adult, and then on to reproduction. But, as Clow explained, the black legged tick can't develop fast enough in the cold, and will run out of its energy stores.

"Previously, in more northern areas, the climate was never warm enough to allow that tick to develop from life stage to the next, before it starved." 

Before the 1990s, Clow said there was a population of black legged ticks at Long Point Provincial Park.

New populations were found on the north shores of Lake Erie and Lake Ontario, and in recent years Clow said there'd been rapid spread of the black legged tick in parts of eastern Ontario, Toronto, Niagara, Hamilton, and as far north as Penetanguishene, Kenora, and Rainy River.  

More than 200 ticks submitted for testing

According to the Region of Waterloo Public Health, people submitted 282 tick and tick queries between January 1 and August 31. 

Of those ticks submitted, 185 were dog ticks and 33 were black legged ticks — six of which tested positive for Lyme disease but a health unit spokesperson said only one of those came from the area.

In that time frame, one lone star tick and one ground hog tick were also submitted for testing, however the lone star tick  also did not originate in the area.