BOZEMAN, Mont., Sept. 13 (UPI) -- Unusually long-lasting hot weather conditions in Montana have prompted U.S. scientists to extend the season for mosquitoes that carry the West Nile virus.
The scientists say Montana's mosquito season will continue well into the last half of September, meaning West Nile virus is still a threat, said Montana State University entomologist Greg Johnson.
Johnson said mosquitoes usually stop biting when temperatures fall below 50 degrees during the night, but that hasn't occurred yet in most of Montana.
In his fourth season studying the West Nile virus, Johnsonhas found Culex tarsalis mosquitoes are the primary carrier in Montana. The mosquitoes usually starts flying shortly after sundown and continues until 1 or 2 a.m.
"Repellents containing DEET or picaridin are most effective," he said. "Several different trade names are available that contain various concentrations of DEET. A repellent containing 20 percent to 30 percent DEET is adequate."
Todd Damrow, state epidemiologist, said he encourages a variety of preventative measures for people. He recommends the use of repellents, avoiding times and places of heavy mosquito activity and covering exposed skin.
