City of Fort Collins to spray for mosquitoes on Sept. 4

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In accordance with the city’s West Nile Virus Management policy, the City of Fort Collins will spray for adult mosquitoes between dusk on Sept. 4 and 1 a.m. on Sept. 5. Weather permitting, truck-based fogging will occur primarily in the eastern side of town, as well as a section in northwest Fort Collins and a small area in Larimer County. A map of spray zones is available at

The City’s contractor, Colorado Mosquito Control, plans to 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 30–60 minutes after spraying occurs. 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.

This is the second spraying application, which increases the efficacy of mosquito control. Following this application, no further spraying will occur this season.

The decision to spray for mosquitos follows the recommendation by Dr. Adrienne LeBailly, Director of the Larimer County Department of Health and Environment, and a majority recommendation from the City of Fort Collins West Nile Advisory panel.

The City of Fort Collins’ West Nile Virus Management Policy aims to reduce the risk of human West Nile virus infection while limiting adverse human health and environmental impacts. The Policy prescribes a data-driven approach to determining when spraying for adult mosquitos should occur. In 2008, a Technical Advisory Committee comprised of community members and professional experts with diverse perspectives developed Program Response Guidelines that establish thresholds for action. The West Nile Management Policy and Program Response Guidelines are available online at

Any recommendation for spraying originates from the Larimer County Department of Health and Environment (LCDHE) and is preceded by a detailed analysis of West Nile virus risk by a three-person West Nile Advisory panel who provide feedback to the City Manager. Per the adopted West Nile Virus Management Police, the City Manager ultimately authorizes spraying.

Residents who live in the spray areas and who are listed with a phone number and address in the White Pages will receive a phone call on Tuesday, Sept. 4 reminding them of nearby mosquito spraying activity. The City also offers an automatic notification system that allows citizens to receive courtesy notices via e-mail any time their neighborhood is going to be sprayed for adult mosquitoes. To be registered for future notices, go to the City’s website at Fort Collins residents without internet access can sign up to receive phone notifications by calling Colorado Mosquito Control at 970-663-5697 or 970-962-2583.

In addition to City-managed adult mosquito spraying, some homeowner’s associations may be hiring private contractors to conduct additional spraying in their neighborhoods. The City of Fort Collins will not provide courtesy notifications for HOA-managed spray programs.

Residents who are registered with the Colorado Department of Agriculture Pesticide Sensitivity Registry will be contacted by Colorado Mosquito Control to discuss shut-off protocol.