County steps up mosquito control |

County steps up mosquito control

B.H. Bose

Earlier in the summer, Kim Sallmen, a technician with the El Dorado County Vector Control division, said he thought it would be a pretty bad mosquito season because of all the precipitation from El Nino. That thought has become a reality as county officials prepare to begin spraying certain areas to reduce high populations of adult mosquitoes.

“There are certain areas in which we are receiving a number of complaints by citizens,” said Virginia Huber, El Dorado Vector Control manager. “We set up traps at night to catch adult mosquitoes and found significant numbers.”

Titled the “adulticiding control program,” it is geared at reducing the large populations of adult mosquitoes that have broken out in selected areas throughout the South Shore. Technicians will go into these high-volume areas on foot and spray a small amount of pesticide called pyrethrum, which is a naturally occurring substance harvested from chrysanthemum flowers. It is the “least toxic available for mosquito control and degrades into nontoxic byproducts within four to six hours,” according to the county’s Environmental Management Department. The spray, expelled in a light, foggy mist, drifts into sites where adult mosquitoes hide.

Technicians are still waiting for ideal conditions before they start fogging the targeted areas. Because wind can easily carry the pesticide away, they must assure there is little to no breeze.

“We could start as early as tonight, if the conditions are right,” said Sallmen. “We can’t give an exact night because it has to be ideal with good climatic conditions.”

Currently, Vector Control is receiving numerous complaints from residents in the Christmas Valley and South Upper Truckee River areas. In the southern portion of the Upper Truckee River, Sallmen said it can get pretty bad because mosquitoes migrate down from areas that are inaccessible to technicians. In turn, the female mosquitoes, which feed on blood in order to gain the necessary nutrients to keep the eggs fertile while the males feed on nectar for energy, can raise havoc on nearby residents.

El Dorado County Vector Control is a division of the El Dorado County Environmental Management Department. It provides mosquito control and surveillance, yellow jacket control, plague surveillance and control, and hantavirus surveillance.

Sallmen and two other technicians are responsible for Vector Control in area No. 3, from Echo Summit to Tahoma to Stateline. Normally, the crew sprays a mixture containing a fatal bacteria and an anti-growth hormone into water sources to kill mosquitoes while they are still in the larva stage. When specific populations in a general area get out of control, fogging is implemented. Considering that many places that were dry at this time last year are still wet this late in the summer, and the fact that it takes only about a quarter-inch of water for many species of mosquitoes to breed, the phone may continue to ring off the hook at the South Lake Tahoe Vector Control office.

“We’ve been having a lot of complaints,” Huber said. “I think we will be seeing it slow down fairly soon, though. Usually we are finished spraying in the first or second week of July, so it has been a significant year for mosquitoes.”

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