Mosquitoes Winning the War in Minnesota

After 35 years of waging chemical war on the mosquito, a growing cadre of Minnesotans are calling for a truce.

They are led by environmentalists, who have long contended that the chemicals aren’t safe and that the control of mosquitoes is interrupting the natural food chain, depleting an important food source for larger insects, birds and waterfowl.

One by one, a growing contingent of cities, park districts and public agencies have been opting out of the state’s Metropolitan Mosquito Control District, arguing that their residents are still swarmed by the insects despite the district’s $10-million annual budget.

Last spring, the St. Paul suburb of Maplewood decided to ask the district to stop spraying for adult mosquitoes on city property. The year before, the Minneapolis Parks and Recreation Board, with jurisdiction over 5,600 acres and 170 parks, said it wanted no more mosquito control, either by spraying for adults or larvae. The Minnesota Department of Natural Resources also has said no to mosquito control in wildlife management and nature areas.

Environmentalists around the country are watching the anti-spraying effort closely to see if political winds are blowing their way.

This year, the heavy summer rains made the problem especially acute, but mosquito control in Minnesota is always a massive task. Each summer Minnesota’s 10,000 lakes and countless wetlands turn the state into a giant hatching farm. A one-acre marsh can spawn 2 million mosquitoes after one good rain. Aggressive mosquitoes can fly for miles in search of a tasty blood meal.

Officials at the district claim that control efforts eliminate at least 80% of the mosquitoes in the heart of the seven-county area around Minneapolis, depending on the weather. The aim is to control mosquitoes that carry encephalitis and other diseases, as well as to make evenings more bearable.

Robert Sjogren, director of the district, said the agency’s methods have evolved from environmentally indiscriminate poison sprays like DDT to today’s biological control agents and less toxic sprays. A technical advisory board and scientific peer review panel have been studying its methods and have discovered no adverse environmental effects from larval controls so far, he said.

Sjogren contends that mosquitoes cannot be controlled naturally by predators like dragon flies, bats and purple martins. He said that when weather conditions are ripe for mosquito production--ample rain and warm weather--residents near no-control areas will notice a difference.

But Harriet Lykken, a Sierra Club member, said the time has come to learn to live with the bugs. She said she wears light colors (mosquitoes are attracted to dark colors), sits in screened-in porches at dusk when mosquitoes are active and uses repellents.

Lykken grew up near the Minneapolis chain of lakes, before mosquito control. “We used to have a lot of mosquitoes--but we still have a lot of mosquitoes. Even if you get rid of a trillion mosquitoes, you’d still have a trillion left.”