Winnipeg Free Press - PRINT EDITION
High-tech Magnet praised, questioned; low-tech clothing, lotion recommended
Gas-powered bug traps, marketed under the name Mosquito Magnet, have begun springing up all over Winnipeg. The question is, do they work?
Without a doubt, says Rachel Donner, who lives in the shady, riverside enclave known as Wildwood Park. Last summer -- remembered by many people as a mosquito nightmare -- was a turning point for her and her three young sons.
"About a week after the mosquitoes arrived, I was so frustrated that I couldn't go outside with the kids," she recalls. "It might as well have been 30 below out there. And these are three children you really don't want to be trapped indoors with."
So when Rachel and her husband heard about the Mosquito Magnet, deciding whether to buy one was a no-brainer -- even with the $800 price tag. When they got the unit home and plugged it in, the effect was almost instantaneous. The children were once again able to play outside, and Donner's sanity was restored.
"We've never looked back," she says.
Donner admits that this summer, thanks to the massive larviciding blitz by the City of Winnipeg, the benefit of owning a mosquito trap is less dramatic. Nevertheless, she remains an enthusiastic advocate.
"The more households that have one, the better," she says.
It seems many other Winnipeggers share this view. David Jackson, seasonal manager at Canadian Tire's McGillivray & Kenaston store, says sales of Mosquito Magnets have been brisk, although they recently began to tail off.
"The city's larviciding program has a lot to do with that," he says.
Mosquito traps work by pumping out a stream of warm, humid carbon dioxide that simulates human breath. The female bugs are drawn toward the source, where they are sucked into a mesh bag. Once inside, they dehydrate and die.
The trap is made more alluring to bugs by adding a small amount of an organic chemical called octenol to the plume of gas that it emits. Octenol is a naturally occurring substance given off by cattle, and mosquitoes find it irresistible.
A range of sizes is available, depending on the area you need to protect. At the lower end of the range, Canadian Tire is offering a small, backyard-size trap for $430. At the top end, you can pay $1,850 for a large unit designed to cover two acres.
Much of the interest in mosquito traps stems from worries about West Nile virus. Last year, Ontario and Quebec had more than 200 confirmed and probable cases of the mosquito-borne disease, and thousands more infections are thought to have gone undetected. At least nine Canadians who carried the virus subsequently died.
Dr. Harvey Artsob, head of zoonotic diseases at the National Microbiology Laboratory in Winnipeg, has described the 2002 data as "staggering."
He predicts Manitoba will follow the same pattern as Ontario. There, the first infections were seen in animals during 2001, and were followed a year later by human cases of the disease.
Robbin Lindsay, a Winnipeg-based research scientist with Health Canada, agrees Manitoba's first human cases of West Nile could appear any day now.
"The next month is when we would typically expect to see human cases of West Nile appear," he says. "I don't think it's time to go and hide in the basement, but equally, people should be taking care.
"It's one thing when mosquitoes are a nuisance, but quite another when there are mosquito-borne diseases flying around out there."
But Lindsay is unconvinced that expensive trapping devices are the best way to protect against West Nile. There's no doubt they collect mosquitoes, often in large numbers. However, that doesn't necessarily translate into fewer bites. In fact, Lindsay believes it may even mean more.
"Because the trap is giving off heat and carbon dioxide, and it's baited with octenol, it may actually be drawing mosquitoes into the area," says Lindsay. "And they still haven't invented a machine that's as attractive to mosquitoes as humans are."
Proving the effectiveness of mosquito traps is not a straightforward business, in part because different regions have their own particular species. "Some are more easily fooled than others," says Lindsay.
For this reason, reliable research is thin on the ground. Nevertheless, Lindsay points to a study carried out last summer in two Winnipeg backyards, in which dedicated volunteers counted mosquito bites throughout a whole season. One yard contained a mosquito trap and the other did not.
"When they looked at the number of bites, there was no fundamental difference between the two yards," says Lindsay.
He believes a better strategy -- and certainly a cheaper one -- is to cover up as much skin as possible with clothing and to protect exposed skin with a DEET-based insect repellent.
With the money you save, perhaps there'll be enough left over to buy a new barbecue.
Republished from the Winnipeg Free Press print edition July 18, 2003 $sourceSection$sourcePage
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