Mosquitoes out in force and early this year in Clark County

Mosquitoes — those much-maligned and all-too-often present pests of summer — have arrived early across Clark County, and in larger-than-usual numbers, as well.

On Tuesday, the Clark County Mosquito Control District reported it has begun work to reduce the onslaught of mosquitoes while treating areas with high numbers of mosquitoes reported.

“We are currently seeing a lot of mosquito activity everywhere in the county, but about one month earlier than last year,” Mario Boisvert, manager for the Mosquito Control District, said in a press release. “Water was released earlier from Bonneville Dam, leading to higher water levels again this year. The above-normal temperatures in mid-May also contributed to earlier hatches.”

Crews typically conduct surveillance and abatement activities from April 1 through October 1. According to the district’s website, the priority is to attack mosquitoes at their source by treating mosquito larvae as they hatch.

The species of mosquitoes currently active in Clark County, called floodwater mosquitoes, lay their eggs in damp soil along rivers during late spring and early summer. As mountain snow melts and water levels rise, those areas become covered with water, and the eggs hatch.

District technicians are setting traps to identify areas with large populations of adult mosquitoes and using trucks to treat those areas. Crews are responding to more than 550 service requests received in the last two weeks, district officials said.

According to the control district’s website, “It is far more effective to reduce mosquito populations at their source, before they fly into neighborhoods, than to fog large, open areas in an attempt to eliminate adult mosquitoes. It is very difficult to reduce mosquito populations once they have spread from the breeding source.”

Treatment methods used by the district include larvicide applied by helicopters, broadcast from trucks, all-terrain vehicles, amphibious vehicles, and on foot from backpack applicators. Larvicide briquettes are placed into storm drains and catch basins. Due to legal restrictions, the district cannot spray or fog neighborhoods or private residences.

Mosquito Control District technicians are also treating thousands of catch basins across the county to prevent the hatching of mosquito species that can carry West Nile virus. Technicians are trapping adult mosquitoes in these areas to test for West Nile virus.

While Clark County has never had a case of West Nile virus that was acquired in the county or a positive test result in a mosquito sample, there have been cases of West Nile virus in other parts of the state, primarily in Eastern Washington.

Clark County Public Health is encouraging everyone to take steps to avoid mosquito bites and eliminate mosquito habitats on their property by installing or repairing screens on windows and doors; remaining indoors during dawn and dusk when mosquitoes are most active; wearing long-sleeved shirts, long pants, shoes, socks, and hats/head nets outside, especially in wooded or wetland areas; placing mosquito netting over infant carriers when outdoors and using EPA-registered insect repellents, including those with DEET, picaridin, IR3535 or oil of lemon eucalyptus. Use of repellents is especially recommended for use at dawn and dusk. Be sure to read the label and carefully follow instructions, especially when applying to children.

Residents can help prevent mosquitoes from breeding on their property by draining standing water from old tires, flowerpots, buckets, plastic tarps, and wheelbarrows; changing the water in bird baths, ponds, wading pools, pet bowls and animal troughs at least twice a week; repairing leaking faucets and sprinklers; cleaning clogged gutters; maintaining swimming pools and checking for containers or trash in hard-to-see places, such as under bushes.

The district will continue surveillance and treatment activities throughout the active mosquito season. To learn more about treatment activities or to submit a request for service, go to https://ccmcd.org.