Mosquito season is here, with threat of West Nile


Residents who hope to reduce the number of mosquitoes on their property, and consequently the threat of West Nile Virus, have a window of opportunity that begins now.

"Mosquito season has started already in parts of Routt County," Routt County Environmental Health Director Mike Zopf told the county commissioners this week. The best way to attack the obnoxious insects is before they reach their adult phase.

"Emphasis right now should be on habitat reduction," CSU Extension Agent C.J. Mucklow said. "Don't allow standing stagnant water on your property. Second, if you can't drain it, we would strongly encourage people to use larvacide."

Larvacide, containing the bacteria Bti (bacillus thuringiensis isaelenscis), is economical and safe for humans and animals, Mucklow said. A dose sufficient to treat 100 square feet of standing water for 30 days can be purchased for $2. One retailer was selling packages of 20 pellets, which resemble small doughnuts, for $22.

The larvacide attacks the digestive tract of mosquitoes.

"The beauty of it is the bacteria is extremely selective," Zopf said. "Butterflies and honey bees (and all other insects but mosquitoes) are safe."

Once the mosquitoes reach the adult phase, they become much more difficult to contain, Mucklow said. A female mosquito can lay as many as 250 eggs every seven days, he added.

Mosquitoes always have been irritants, but Zopf said there is more urgency than ever this spring because West Nile Virus is spreading in the western United States. The disease can be spread from birds to mosquitoes to humans or livestock. Although there have been no diagnosed cases in Routt County, the disease "poses a real problem," Zopf said.

"It's not if, but when," Zopf said. "It's just a matter of time until we see it all the way to California."

West Nile claimed the lives of 99 horses in Colorado last summer, one of them in Moffat County. The disease was detected in 13 people in the state, none of them locally. None of the human cases resulted in death.

The virus is spread by infected birds, which are able to transport it over long distances. Mosquitoes that bite the birds can, in turn, spread the disease when they bite animals and humans. There are many species of mosquitoes, but one in particular is most often responsible for the spread of West Nile.

Zopf and Mucklow have applied for a grant that would allow them to conduct research specific to the threat of West Nile virus in this region. They want to determine if the mosquito most commonly known to spread the disease is present at this elevation.

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-- To reach Tom Ross call 871-4205

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