Tick Tock

The bloodthirsty parasites are spreading north — and making the woods more dangerous than ever

- STEPHANIE NOLEN

WHEN KATIE CLOW and her research students arrive in a windowless lab at the Ontario Veterinary College, in Guelph, Ontario, on a drizzly late-fall morning, envelopes have piled up on their workbench like a manila snowdrift. They slip on white coats and reach for scissors to start slitting open the padded packets. Each one contains a slip of paper and a small plastic vial or two. The paperwork lists the name of a veterinary clinic somewhere in Canada and the identifying details of someone’s pet: a six-year-old golden retriever in Moncton, a four-year-old tabby in Victoria.

Inside each corresponding vial is a tick — or fifty — plucked from the body of that pet and mailed in for research. With her team, Clow, a professor of veterinary medicine with expertise in epidemiology and ecology, opens the vials and tips the rigid bodies of the arachnids into a petri dish. Unless they’re not dead: after a week or two in the custody of Canada Post, they sometimes emerge and start scurrying across the bench. When a live one tumbles out in front of research assistant Kiera Murison, she snatches a pair of tweezers to pluck it up and deposits it into a vial of ethanol, with a whispered apology, swirling it around to bring a prompt demise.

When the ticks are all definitely dead, they are stored in the fridge until Clow, an ebullient thirty-two-year-old whose students call her the Tick Queen, has time to sit down with a box of them. She identifies the ticks quickly, by species and by gender, based partly on the appearance of their hard outer shell, called a scutum, and sometimes by the shape of their protruding mouthparts. Most of the ticks mailed to her Canadian Pet Tick Survey are American dog ticks,