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map of south Fort Collins showing mosquito spray zone for July 17 and 20, 2025

Spray zone map for July 17 & 20, 2025

City to spray for mosquitoes in south Fort Collins July 17 & 20

Based on high levels of West Nile virus infected Culex mosquitoes trapped last week, the City of Fort Collins will spray for mosquitoes in south Fort Collins.

Spraying will occur by fogging trucks on both Thursday, July 17 and Sunday, July 20, weather permitting; it will begin at approximately 8 p.m. each night and end by approximately 2 a.m. the following morning.

Spraying will take place in the area from:

  • Taft Hill Road to Ziegler Road, between Horsetooth Road and Trilby Road. This will also include the portions of the Westchase and Kechter Farm neighborhoods south of Trilby Road.

The entire spray area will be treated on both nights.

The City’s contractor, Vector Disease Control International (VDCI), will use a permethrin-based product to be applied in a fine mist. To minimize pesticide exposure, residents should stay indoors and keep doors and windows closed for 30 to 60 minutes after spraying. It’s recommended that residents bring pets indoors as well. Residents can further minimize pesticide exposure by covering organic gardens, ponds, and water features with a sheet or tarp.

The City consults with the Parks & Recreation departments, Poudre School District, and Colorado State University on any scheduled outdoor events within the spray zone, and will adjust schedules to spray in those areas later in the evening, after events have concluded.

The decision to spray for mosquitos follows the recommendation by the Larimer County Department of Health and Environment, in accordance with the City’s West Nile Virus Management Policy.

West Nile Virus Information

West Nile virus is a disease that is transmitted to humans by mosquitoes. The symptoms of West Nile virus range from none to very serious.

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Protect Yourself

Help protect yourself from mosquitoes and West Nile virus with the Four D's! Report possible mosquito breeding sites, and learn the best ways to prevent mosquito breeding at home.

Protect Yourself

Mosquito Spraying

Sign up to receive alerts if the City decides to spray for mosquitoes, and learn more about the spray process.

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Local Data

View the weekly vector index and trap reports during the summer testing season, as well as monthly and annual program reports.

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Technical Advisory Committee

The Technical Advisory Committee is comprised of community experts who provide technical expertise and recommendations to City Council regarding the City's West Nile virus policy.

Technical Advisory Committee

City's West Nile Virus Management

Review the City's West Nile Virus Management Policy and Response Plan. The City has contracted with Vector Disease Control International to conduct mosquito surveillance and mitigation.

Program Policy & Management