Valley gets break from mosquitoes this summer

Flathead County has something to celebrate in 2009 - fewer mosquitoes and no West Nile virus found among trapped mosquitoes.

"Over all, mosquito numbers are down," said Bruce Gunderson, county mosquito program coordinator.

He said control efforts were helped by a slow, sustained spring runoff. However, heavier snow in the valley caused early emergence of ground water and snow-melt ponds that the county treated with larvicides to reduce adult mosquitoes.

"Complaint calls are way down," Gunderson said.

Along with fewer mosquitoes, he said the county's trapping program and others around the state have found no mosquitoes infected with West Nile virus.

"The only cases across the United States are in South Dakota and Texas," he said. "But it's still kind of early in the year."

Most often, the first cases emerge in mid- to late August. Gunderson said the department plans to continue surveillance for West Nile virus through the end of August.

The efforts include placing traps baited with dry ice once a week in Evergreen and Whitefish. Dry ice produces carbon dioxide, the gas exhaled by people and animals that attracts mosquitoes.

According to Gunderson, the trapping program was reduced this year because of a cutback in funding for Montana from the Centers for Disease Control.

"We used to have 10 sites in the Flathead Valley," he said.

Gunderson started the season with two employees to treat areas of standing water. He cut back to one because of the smaller mosquito problem this year.

The county program employs GPS mapping to keep track of areas of standing water. Software puts up a red flag when the treatment's effective date expires.

"We've come a long way in three years on mapping and tracking areas," he said.

Gunderson encourages people to call him about places suffering mosquito invasions. His first question is "Where is the body of water producing the mosquitoes?"

He said homeowners usually know the answer. Their own home may contribute to the problem with ponds or pools, sagging car or boat covers or tires with standing water.

"Tires are huge," Gunderson said.

It takes very little water to hatch a lot of mosquitoes. He said he has found 100 to 150 mosquito larvae in as little as a cup of water.

This year's mosquito season stands in stark contrast to 2008 when the program declared 52 areas of infestation - compared to none this year. An infestation is declared when an estimated 100 mosquitoes land on a person within one minute.

"Last year, we were working with mosquito nets over our heads," Gunderson said.

Reporter Candace Chase may be reached at 758-4436 or by e-mail at cchase@dailyinterlake.com.