The Summer of the 'Squito?

Thursday, June 8, 2006

If you’ve been outside lately, then you may have noticed that the city seems to have a wee bit of a mosquito problem. Of course, mosquitoes have generally been a problem across the country in recent years due to the fact that they carry the West Nile Virus, an illness that mimics many flu symptoms, but can be deadly depending on the severity of the case.

To get the low down on what I’m calling Mosquito Madness ’06 (patent pending), I went straight to the source: U of G entomologist James Heal in the Department of Environmental Biology.

“Because we had such a mild winter and such a warm spring, the mosquitoes are about three weeks early,” says Heal. “Their development is temperature dependent, the warmer it is outside – the faster they develop. I’ve never seen biting mosquitoes in April before, this is a new record; it used to be a question if we’d even have them by the Victoria Day Long Weekend.”

According to Heal, June is the peak time for the mosquito population. Mosquitoes that have survived the winter begin to emerge, new mosquitoes are spawned and gradually over the hot days of summer, the population begins to die out. However, mosquitoes are usually not aggressive at this time of year because at this stage of their development they aren’t yet hungry.

“There are 50 different mosquito species in Ontario, some just have one generation a year, but some can have more because of these rainy summers,” says Heal. “If we have a rainy and warm summer there’s a handful of species that will increase in number. Some of those transmit the West Nile Virus.”

Cameron Clark, Program Manager in Health Protection of the Dufferin-Wellington-Guelph Health Unit, concurs with Heal’s assessment. “The first occurrence of the virus will be found mid-summer in the bird and squirrel populations. This is a spring hatch and they’re not necessarily carriers of West Nile and there are different from the ‘nuisance’ mosquitoes we have now.”

So the mosquitoes biting now will have died off by July, but depending on the weather there may equal numbers of later generations in the late summer, and those are the ones that Heal says we should be worried about.

“Just because we had early mosquitoes I don’t think that’s going to affect what happens with West Nile,” says Heal. “The ones that give us West Nile are feeding on birds right now, then when the birds disperse in August, that’s when they start biting people.”

Clark says that there really is no predictive indicators that can be employed in order to prognosticate as to whether this will be a bad year for West Nile or not. “Fiona Hunter of Brock University has come the closest to a predictive model by using hot temperatures that help breeding followed by cooler weather that allows mosquitoes to live longer.”

So, for right this minute, one need not fear the West Nile. In fact, GDWHU isn’t even starting their trapping until next week. Still, it’s small comfort to Guelph residents trying to enjoy the great outdoors. For those people, Heal offers the following advice.

“There’s avoiding mosquitoes when they’re most active, which is around dusk. That’s between 7:30 and sunset when they’re really most active. If you have to be outside you can wear long sleeve shirts and pants, pick a really tight cotton wool that’s tough for mosquitoes to bite through. If you want to use repellent, there’s deet, which is actually very safe if you use it as directed on the label.

“Then there’s alternatives to deet that are plant oil-based products, like citronella oil which will give you 30-60 minutes of protection. The company OFF has a great product called OFF Botanical and that gives you two solid hours of protection, it’s a lotion.”

In the meantime, the Health Unit will put its focus on an educational campaign to get the general public to remove standing water from their property. “Were using our education budget to put ads in community guides and make pamphlets,” says Clark. “Our message is more about removing standing water because mosquitoes like small pools of water, like tin can lids, bird baths and tires.”

Clark is also asking people with backyard pools to check their pool covers for standing water. In fact, Guelph already has a by-law on the books concerning standing water and pool covers, a by-law, Clark says, that may end up being more heavily enforced.

So to summarize the current state of Mosquito Madness ’06 so far: mosquitoes are more aggressive than normal for this time of year, with a hot summer their population could decrease as the months go on, and there is no risk of West Nile…yet. Stay tuned.

| More
Bookstore First Year