Wet, warm spring means it's a good year for the mosquitoes. But the Metropolitan Mosquito Control District is stepping up its attack.
Metropolitan Mosquito Control District lab is where mosquito populations are examined. The Aedes Vexans is the most common species of mosquito locally. The West Nile virus has not been tied to a certain species in Minnesota. This is a view through a microscope of dead mosquitos that had been recently captured from one trap.
Here's one more byproduct of the long, wet, warm spring: Metro-area residents may be swatting more mosquitoes than in recent summers, despite a broadening battle against them.
The Metropolitan Mosquito Control District has already treated nearly the number of mosquito-breeding wetland acres that it treats in an average year, but "that also means people are going to experience more near-normal levels of adult mosquitoes," executive director Jim Stark said.
"The last few years we've gotten a little spoiled by the [low] numbers of mosquitoes," Stark said.
The agency normally treats wetlands in the seven-county metro area with a bacterium that fatally disrupts the digestive systems of mosquitoes and other small related insects. It also uses a substance that prevents mosquito larvae from becoming biting egg-laying adults. Those materials are usually dropped into wetlands from helicopters and by workers on foot.
This year, the agency is stepping up its use of spraying, and employing trucks and workers with backpacks who can spray heavily vegetated areas where adult mosquitoes might be congregating, Stark said. Usually operating in the evening, when winds are light, the workers spray a synthetic analogue of a material derived from chrysanthemums that kills the adult insects. The workers will treat both public and private land, Stark said.
Attacking larvae is more effective, Stark said, but this year the population of adults, including those that are known to carry diseases, is likely to be greater than in recent years.
Even normal rainfall the rest of the summer will require treating a record acreage, Stark said. That could be as many as 250,000 acres, or nearly 400 square miles across the seven-county metro area.
The Twin Cities had its second-rainiest May on record. That could boost the population of one of the most common biting species of mosquito, whose eggs can lie dormant for several years until they're flooded.
With Minnesota's climate trending over the longer term toward wetter and warmer conditions, Stark added, it's possible Minnesota will see longer mosquito seasons and new species.
"It's an ever-changing target we're after," he said.
While whining mosquitoes always get Minnesotans' attention, University of Minnesota Extension entomologist Jeff Hahn said two key garden pests -- Japanese beetles and earwigs -- should also be emerging soon.
Meanwhile, the report of a buzzing cicada -- characteristic of midsummer -- last week in south Minneapolis was unusually early, Hahn said.
Bill McAuliffe • 612-673-7646