Mosquito Control District

 6/16/20- A note about mosquitos in Ridgefield: Mosquito District crews began treating mosquito larva at the end of March and noted that larva populations remained relatively small through April. In early May, crews noted more significant larva populations, which required aerial larva treatment by helicopter. Larva treatment by helicopter was performed May 11-12 and May 28-29.   

The district traps adult mosquitos to monitor populations and test for disease. On June 1, 18 traps were set throughout west Ridgefield and the Ridgefield National Wildlife Refuge. One of the traps from the refuge yielded a very high adult mosquito population. In response to an increase in service request from the Ridgefield area, the district began treating areas for adult mosquitos by fogging non-populated areas. While the district is not set up to fog and treat for adult mosquitos in the neighborhood areas, we will continue to fog non-populated areas to reduce adult mosquito populations before they move into the neighborhoods.

National Wildlife Refuge rules limit the district’s actions on the property. The district is requesting additional access and treatment for mosquitos on the refuge. Until access is granted we will continue to monitor and treat larva in the areas that we can access, as well as treat and fog for adult mosquitos when we can. If you have any questions please contact us on our service request line 564.397.8430 or https://www.clark.wa.gov/public-health/mosquito-control-service-requests and we will return your call as soon as we can.

Mosquito season has begun!

Clark County Mosquito Control District, as an essential service, is still serving the community by treating for mosquitoes and responding to mosquito control service requests. The health and safety of the citizens we serve and of our employees is paramount during the COVID-19 pandemic. To protect everyone, we have implemented the following measures to promote social distancing and to adhere to Center for Disease Control and Prevention (CDC) recommendations and Washington Gov. Jay Inslee's Stay Home -Stay Healthy proclamation:

  • Increased cleaning of surfaces at the shop
  • Increased cleaning of trucks and equipment
  • Vehicles assigned to individual employees
  • Reusing existing personal protective equipment to preserve available supply
  • Staying home when sick.

To protect everyone and adhere to social distancing guidelines, please stay at least 6 feet away from Mosquito Control employees treating for mosquitoes. If you are experiencing a mosquito problem, please submit a service request on our online form here or leave a message at 564-397-8430.

Mosquitoes do not spread coronavirus

Can mosquitoes transmit the coronavirus?

The CDC reports that:

  • Not all types of viruses can be spread by mosquitoes and ticks. ​
  • At this time, we have no data to suggest that COVID-19 or other similar coronaviruses (e.g. SARS, MERS) are spread by mosquitoes or ticks. 

Public Health and the Mosquito Control District work together to control mosquitos in Clark County. District activities are guided by the work plan adopted by the Mosquito Control Board of Trustees to address mosquito nuisance abatement and threats of West Nile Virus.

Abatement and operations 

2/14/2020 - The Clark County Mosquito Control District will begin seasonal activities soon. Click here for more information.


The Clark County mosquito crew conducts surveillance and abatement activities through the active mosquito season, usually April 1 through October 1, each year. The priority is to attack mosquitoes at their source, by treating mosquito larvae as they hatch. It is far more effective to reduce mosquito populations at their source, before they fly into neighborhoods, than to fog large, open areas in attempt to eliminate adult mosquitoes. It is very difficult to reduce mosquito populations once they have spread from the breeding source.

Control measures used by the crew comply with policies adopted by the Board of Trustees of the Mosquito Control District and with state and Environmental Protection Agency regulations. Biological control methods are used that have the least adverse effect on humans, pets, wildlife, and the environment.

The crew implements an Integrated Pest Management (IPM) program and uses a variety of equipment to control mosquitoes. Treatment methods in Clark County 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. Limited treatment is applied to adult mosquitoes due to the limited effectiveness of this method and the short duration of the materials. Due to legal restrictions, the Mosquito Control District cannot spray or fog neighborhoods or private residences.

Service request

The Clark County mosquito control crew works April 1 through October 1 each year. During that time requests for service or information regarding mosquito control can be made through either the 24-hour service request line at 360.397.8430 or on-line service request.

When reporting an area of standing water, please provide the following information:

  • Your first and last name (please speak clearly and slowly, and spell your last name).
  • Your address, including city and zip code.
  • Your telephone number.
  • Description and location of the problem.

A mosquito crew will visit the problem area and determine treatment or monitoring needs. You will receive a phone call only if additional information is needed to find the problem site.