The good news (and bad) about this summer's mosquito season

 
 
Updated 6/1/2018 5:44 PM
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  • The Northwest Mosquito Abatement District in Wheeling tests mosquitoes for West Nile virus.

      The Northwest Mosquito Abatement District in Wheeling tests mosquitoes for West Nile virus. Joe Lewnard | Staff Photographer

  • Lab and Field Intern Elizabeth Lopez works at the Northwest Mosquito Abatement District in Wheeling, where the insects are tested for West Nile virus.

      Lab and Field Intern Elizabeth Lopez works at the Northwest Mosquito Abatement District in Wheeling, where the insects are tested for West Nile virus. Joe Lewnard | Staff Photographer

  • Lab and Field Intern Elizabeth Lopez views a mosquito through a microscope at the Northwest Mosquito Abatement District in Wheeling, where the insects are tested for West Nile virus.

      Lab and Field Intern Elizabeth Lopez views a mosquito through a microscope at the Northwest Mosquito Abatement District in Wheeling, where the insects are tested for West Nile virus. Joe Lewnard | Staff Photographer

  • Patrick Irvin shows a mosquito trap at the Northwest Mosquito Abatement District in Wheeling, where the insects are tested for West Nile virus.

      Patrick Irvin shows a mosquito trap at the Northwest Mosquito Abatement District in Wheeling, where the insects are tested for West Nile virus. Joe Lewnard | Staff Photographer

  • A mosquito is viewed under the light of a microscope at the Northwest Mosquito Abatement District in Wheeling, where they are tested for West Nile virus.

      A mosquito is viewed under the light of a microscope at the Northwest Mosquito Abatement District in Wheeling, where they are tested for West Nile virus. Joe Lewnard | Staff Photographer

You probably don't need anyone to tell you how bad the mosquitoes have been lately in the suburbs.

The wettest May in Chicago's history and a stretch of record-tying high temperatures have combined to cook up the perfect conditions for millions of mosquito eggs to develop, experts say. Typically, mosquito season doesn't kick off until mid-June.

"When we're out and about, we find that people are surprised," said George Balis, an entomologist at Clarke Environmental, which handles mosquito abatement for parts of Lake, McHenry, Kane, DuPage and Cook counties.

What can we expect for this summer? And will the risk for West Nile virus be higher than average?

Here's the bad news and good news.

Bad news: Obviously, the mosquitoes have gotten off to a very strong start, in part because 8.2 inches of rainfall was recorded at O'Hare International Airport in May, breaking a record of 7.5 inches in 1945. Then there was the three-day stretch of 90-degree temperatures -- the earliest in the year since 1977 -- which sped up mosquitoes' metamorphosis.

Good news: A strong start for mosquitoes doesn't mean they'll hang on for the whole summer, Balis said.

"It's hard to really designate an entire year by the beginning of the season," he said.

Just as the weather can quickly change, so too can the conditions for mosquitoes to multiply. But the perfect conditions are different for relatively harmless but pesky mosquitoes and those that actually carry infections such as West Nile virus.

Bad news: The first mosquitoes in Illinois found to be carrying the West Nile virus were found in the Northern suburbs of Glenview and Morton Grove last week, though no human cases have been reported, Illinois Department of Public Health officials said. West Nile virus has been reported in the state every year since 2001.

Good news: For the past several years, scientists at the University of Illinois have been forecasting the weekly risk of West Nile virus by analyzing weather patterns favorable to culex pipiens -- the type of mosquito that carries West Nile virus. The species prefers drier and warmer weather.

Their most sophisticated modeling system is based in DuPage County, where a high number of mosquito traps provide strong data.

With the average rainfall last fall and bitter low temperatures in January, this summer so far is not shaping up to be an especially bad year for West Nile virus, said Marilyn O'Hara Ruiz, the director of the university's geographic information science and spatial epidemiology lab.

Bad news: We're not out of the woods. Ruiz said the next several weeks will provide insight. If the infection rate starts mirroring 2012, the state's worst year for West Nile virus, there could be trouble.

Balis said that whether or not the risk is high, it's always important to wear insect repellent and remove standing water.

"When you have exposure to mosquitoes, there are things you can do regardless of whether they are West Nile mosquitoes or quality-of-life mosquitoes," he said.

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