After a 40-year lull, bedbugs are showing up in ever greater numbers across Canada, thanks in part to jet-setting travellers who accidentally import them from Asia and Africa.

Exterminator John Van of the Vancouver-based company BC Pest Control has treated 65 rooms in one hotel alone, as well as university dorms and private homes.

He says the number of bedbug calls to his office is 50 times what it was five years ago.

Bedbugs are typically five to seven millimetres long.

"It's virtually impossible to treat a place just once and have success," he said. "You'd have to do it at least two or three times."

The bugs hitch a ride in clothing and soft-sided suitcases, then make new homes in mattresses in hotels, university dorms and private homes as they wait for a warm-blooded victim upon which to feast.

Entomologist Judy Myers feels the bedbug problem is only going to grow, largely because of their ability to survive.

"If there's nobody around, they can live for up to a year without feeding," says the University of British Columbia professor. "They're hard to get rid of."

The approximately five-millimetre long insect is not a disease carrier, but is certainly a nuisance, causing itchy, painful welts to rise on bitten skin.

Some of the reasons bedbugs are so hard to kill:

• They can hide in cracks the thickness of a nickel where it's difficult for sprays to spread.
• Finding all the bugs and eggs can require multiple visits from an exterminator.
• They can hide in bedding, upholstery, carpet and clothing as well as mattresses.
• They emerge from their hiding spots only at night.
• A single female can lay up to 300 eggs, causing populations to grow and spread quickly.

Experts say the best way to prevent an infestation is to vacuum mattresses regularly and wash linens in hot water.

The problem has been popping up all across Canada in the past 18 months.

Tenants in a 21-storey Manitoba Housing complex in Winnipeg have been suffering from bites since an infestation began in April 2004.

And Toronto's bedbug population has been steadily rising, with infestations reported everywhere from upscale condominiums to homeless shelters.