Ticks, mosquitoes and ants will swarm Minnesota's summer

The wet spring could produce a bumper crop of ticks. Swarms of mosquitoes are a few significant rainfalls away. And colonies of ants already are marching through Minnesota, say experts who warn of insect-related diseases, swelling bites and pesky, uninvited guests.

Although this year's tick season was delayed because of late snowfall, June could be the worst month for bites and tick-borne illnesses such as Lyme disease, said Dave Neitzel, a Minnesota Department of Health epidemiologist who specializes in mosquitoes and tick diseases.

"We expect the highest-risk period for tick-borne diseases to occur over the next few weeks in Minnesota," Neitzel said. "These ticks have a hard time surviving in extremely dry weather. They thrive in wet, humid conditions."

While the unusually cool spring delayed the advent of tick and mosquito season by a week or two, Elizabeth Schiffman, a state epidemiologist, warns that small, immature ticks — nymphs — already are extremely active.

Regions Hospital in St. Paul has seen an increase in patients requesting tests for tick-related diseases, but not an increase in positive results so far, according to Doug Olson, medical director for the pathology lab.

Before a sharp decline last year, Minnesotans had tick-borne illnesses diagnosed at elevated rates between 2007 and 2011, with more than 1,000 cases of Lyme disease, the most common type, found each year. After 1,201 confirmed Lyme cases in 2011, the number dropped to 911 in 2012.

Neitzel said that the decline may have been due in part to people taking more preventive measures but that dry conditions last year probably were a bigger factor.

As for lowering risks, officials advise people to avoid wooded areas if possible, check often for ticks and use DEET-based repellent.

Mosquitoes are another matter. They can't be avoided.

Jim Stark directs the Metropolitan Mosquito Control District (MMCD), which could spend up to $17 million this year in its never-ending battle with the unofficial state bird. This year's mosquito crop was delayed in development about three to four weeks because of the cool spring, Stark said. But they're coming. And they seem to regenerate with every rainfall.

People risk mosquito-related diseases such as encephalitis and the West Nile virus. Dogs are at risk of heartworm.

Stark remains encouraged as the MMCD continues to spray 2,700 square miles that include half the state's population — making the metro area one of the largest-funded mosquito districts on the planet.

"Year-end summaries indicate our rate of disease is a fraction of what it was in South Dakota last year," Stark said.

But he warned that as the weather gets hot and Minnesota has fewer "pest" mosquitoes, the population of "disease" mosquitoes increases.

Gardeners will find fewer insect problems, but more disease concerns with wet weather, said Deb Brown, retired University of Minnesota extension horticulturist.

Those pesky ants favored last fall's unusually dry conditions, which helped them maintain colonies, said Mary Meyer, university extension horticulturist.

"I'm seeing more ants," said Meyer, who wears gloves when she works. "I have bite marks all over my wrists."

ashley.griffin@startribune.com 612-673-4652

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