Two mosquito control agencies in the Chicago area are reporting noticeably higher numbers of floodwater mosquitoes after months of rain. And the skin-slapping and itching is only expected to continue as forecasters predict more rain for this weekend.
In Wheeling, crews for the Northwest Mosquito Abatement District say mosquito traps began averaging counts higher than 35 insects the week of June 25 to July 1. Trap numbers above the 35 mark are usually when the public begins to feel uncomfortable, said Mike Szyska, director of the district that handles mosquito control for eight suburbs.
Last year in the same time period, floodwater mosquito traps were only averaging about 20 insects, Szyska said.
Similarly, in Chicago’s North Shore suburbs, mosquito control crews saw the number of floodwater insects jump from 29 to 314 from June 27 to July 5, a striking indication of the growing population, said Dave Zazra, communications manager for the North Shore Mosquito Abatement District.
And with wet conditions expected to return this weekend, conditions will remain ripe for the so-called “nuisance mosquitoes” to continue reproducing in high amounts, experts said. The National Weather Service is predicting an inch and a half of rain in sporadic showers throughout tonight, tomorrow and Sunday.
“It’s a little never ending cycle going on here,” said Szyska. “People are definitely going to notice there’s a problem out there.”
Typically this time of year, mosquito control experts expect one “brood” or hatching of mosquito eggs which are laid in the soil right above the water lines of ponds, swamps and other pools of water. But this year’s steady rainfall has prompted at least four or five broods – with another one expected either late this weekend or Monday, Szyska said.
Floodwater mosquitoes need consistent wetness to trigger hatching. The bugs become noticeable anywhere from 7 to 14 days after a rain when female mosquitoes start looking to feast on human blood, which contains proteins needed to allow them to lay more eggs, experts say.
The frequent rains, in some cases, have even caused mosquito eggs laid several years ago to hatch, making the population feel more like one continuous “super brood,” as opposed to separate surges every several weeks after a big storm, said George Balis, regional manager and entomologist for Clarke Mosquito Control in Roselle.
“It seems like mosquitoes are continuing to emerge, rather than after one single rainfall,” Balis said. “That’s something that we don’t see very often.”
And Mother Nature isn’t helping.
Crews from the North Shore abatement district were forced to call off two of their three nighttime spraying runs last week because the rain or cool temperatures would have made the effort pointless. “Mosquito activity tends to be limited under those conditions,” said Zazra. “If the mosquitoes aren’t out, that limits them from contact with our spray.”
Rainfall recorded at O’Hare International Airport has been above average for the months of May, June and July, with the precipitation spread out over many days. In May, nearly five inches of rain fell over 14 days. In June, 7.81 inches of rain fell over 13 days; and so far in July, 1.36 inches of rain have been recorded over four days, said Bill Morris, hydrologist for the National Weather Service.
The only good news is that the wet conditions have also led to a decrease in the number of the type of mosquito that carries West Nile virus, a serious health concern.
As of Thursday, the Illinois Department of Health saw 33 positive samples of West Nile virus out of 3,476 mosquitoes tested. That number is down from last year at this time, when there were 79 positive samples out of 5,954 mosquitoes collected, according to Melaney Arnold, spokeswoman for the department.
It’s little consolation, however, to Anthony Lappo, 29, of Addison, who sprayed himself with mosquito repellent before heading outdoors for barbecues, soccer practice and other activities.
“Everyone’s just swatting,” said Lappo. “Usually I never use spray, but with all the bites I have to.”