June 24, 2019

Getting ready for mosquito season

The annoying buzzzzzzzzz of mosquitoes hovering near your head and swooping in for a bite is one of the less attractive aspects of summertime in Wisconsin. But with news of mosquito-borne illnesses dominating headlines in recent years, how much do you have to fear from those little blood-suckers? That depends.

“Virtually every summer season is a bad summer in Wisconsin for mosquitoes,” says Jonathan Temte, MD/PhD, a professor with the UW Department of Family Medicine and Community Health and chair of the Wisconsin Council on Immunization Practices. “It all depends on how much rain we get and how much standing water we have. That allows for the acceleration of the population of mosquitoes. The entire life cycle for our good friend the mosquito is 8-10 days, and that’s at room temperature. As with all things insect, warmer temps tend to increase the rate at which maturity occurs, so a seasonally cool summer will delay things a bit. A warmer summer with warm surface water will accelerate the mosquito population.”

Mosquito-proof your summer

Here’s what you need to know about those pesky backyard denizens and how to mosquito-proof your summer.

There’s more than one type of mosquito. “Wisconsin is blessed with 56 species of mosquitoes, and some are more prone to visit people than others. They also have different feeding times,” Temte explains.

Wisconsin mosquitoes are less harmful than some but can still get you sick. “Fortunately, Wisconsin doesn’t have a lot of things that have been in the news over the past three or two years: we don't contend with Zika or Chikungunya, two newly emerging diseases in the Western hemisphere,” Temte says. “But things that are more transmittable are West Nile and mosquito-borne encephalitis. Encephalitis can cause pretty significant inflammation of the lining of the brain. People can get relatively ill and have pretty severe consequences, but fortunately, it tends to be relatively rare.” If you’re traveling to an area where mosquito-borne disease is more of a problem, you’ll want to be more cautious.

You can catch a virus from a mosquito and not even know it. “The West Nile virus is probably much more common than the encephalitis virus, however, most people that encounter West Nile never need medical attention,” he notes. “If you get a low-level headache, or feel a little bit feverish, that might be West Nile. But only one in 200 or 250 individuals with West Nile actually presents with symptoms, and once you’ve had West Nile, you’re probably protected for a very long time, if not your life.”

Some people are more at risk. “In terms of mosquito-borne disease, with things like West Nile and along with most viral disease in general, the very old and the very young tend to have more consequences,” he says. mosquitoes track their prey by following carbon dioxide, and research shows that some people — including pregnant women — are more attractive to mosquitoes.

Tips to keep mosquitoes away

Eliminate nearby mosquito attractions. “Keep in mind that mosquitoes aren’t traveling over long distances to bite you,” Temte notes. “mosquitoes that bite you in your yard are homegrown, from less than half a football field away. Remember, those puddles only have to be there seven-to-10 days to be an ideal incubator for mosquitoes.” Consider whether you want to keep that bird bath filled or whether you could add mosquito-eating fish to a backyard water feature. mosquitoes that carry the La Crosse encephalitis virus tend to breed in pot holes or tree holes that fill with water, so be on the lookout for other nearby breeding grounds.

Cover up. The first step to reducing your contact with mosquitoes is to cover your skin, especially when out in the mosquito-happy hours of pre-dawn or evening. Although mosquitoes can bite through clothing, long sleeves and pants are a deterrent. If you find you’re frequently mosquito bait, you may want to invest in insect-repellent clothing, such as the Permethrin-infused fabric sold at camping stores. “These actually can go through the wash several times without losing their potency, and they’re also considered safe for younger children and pregnant women,” Temte says.

Reach for the bug spray. Some swear by mosquito repellent options that include essential oils, such as oil of lemon eucalyptus, while others rely on the more standard insect-repellent chemicals. “Hands down, DEET has the best data behind it behind when it comes to repelling mosquitoes,” Temte says. “If I’m going to be spending a lot of time outdoors, my tendency is use the spray-on DEET.” Concentrations of 30 percent or less are safe for everyone, even children, he says.

Keep moving. “If you’re in moving air or actively moving — walking, biking or running — you’re less likely to get bit,” Temte explains. “If you’re sitting, standing or working in the garden, they’re more likely to bite you. mosquitoes are just not that strong of fliers, and they’re not that fast.”

Encourage bats. Wisconsin’s bat population is plummeting due to a fungal disease, which means mosquito populations are more likely to boom. “Bats are really our friends here with mosquitoes: a good little brown bat might eat as many as 1,000 mosquitoes in a 24-hour period,” Temte notes. If you want to encourage a backyard bat habitat to keep mosquitoes in check, the Wisconsin Department of Natural Resources offers this guide to building a bat house.