West Nile And The Late-Summer Swarm

Sept. 7, 2010, 9:22 a.m.

By Kendall Walters - Kamloops This Week

Though the massive swarms of mosquitoes seem to have died down by this point in the summer, now is the time to be diligent in preventing bites from the pesky insects.

This month, a crow in Kelowna tested positive for West Nile Virus.

It is the first time in B.C. a crow has tested positive and it’s the farthest north West Nile has been detected.

Last year the virus only got as far as the south Okanagan.

“That’s about 100 kilometres closer than we were expecting this year,” said Cheryl Phippen, owner of BWP consulting, which has the Kamloops mosquito-control contract this year.

Phippen said people need to be on guard against mosquito bites right now as the species of mosquito able to carry and transmit West Nile is out in large numbers.

“This is when they peak,” Phippen said. “Early to mid-August is when they’re at their highest numbers.”

According to Phippen, the mosquitoes out in early summer, swarming in large groups, are a different variety, which, after biting once, die.

This means they are unable to transmit the disease.

However, the bugs out now, which also hatched at the beginning of the summer, are able to bite every 10 to 15 days and, consequently, have had numerous opportunities to pick up the disease.

Every time they bite, they lay more eggs. The result: the West-Nile transmitting mosquito is out in large numbers

“They have a lot of opportunities to pick up West Nile virus,” Phippen said.

“They’re at their most dangerous. Now is the time to be diligent.”

The species that can transmit the virus prefers hot, dry valley bottoms.

To prevent bites, Phippen recommends wearing insect repellent with DEET, sticking with light-coloured, loose clothing and avoiding mosquito-filled areas at dawn and dusk, when the bugs are at their most active.

She also reminds the public to make sure there’s no standing water in their yards.

“Any standing water that’s left in the city is loaded in mosquito larvae,” she said.

Phippen’s team has been treating standing water, such as catch basins and ponds, with Aquabac, a certified organic bacteria that is deadly to mosquito larvae, but harmless to everything else, including other insects.

If you have a pond, pool, plant saucers or other container of standing water, Phippen advises dumping it out.

If it’s something that cannot be dumped, the water can be treated with Aquabac, which can be purchased at garden centers.

If you come across a dead bird, report it to the Interior Health Authority West Nile Virus information line at 1-866-300-0520.

Phippen said since the report of the West Nile-positive crow in the Okanagan, reports of dead birds have spiked dramatically.

“A lot more people are reporting birds,” she said, noting the team usually receives one or two reports in a week.

“I’ve been getting 30 in a day,” she said.

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