Mosquitoes Carrying West Nile Virus Found in Greeley
Residents can help protect themselves by following the ‘Four D’s’
GREELEY, Colo. — The City of Greeley has begun mosquito spraying operations after trapped mosquitoes tested positive for the West Nile Virus. The virus can spread to people and animals by bites from infected mosquitoes.
In Colorado, these viruses are transmitted to people by a species called Culex tarsalis. These mosquitoes are most active around dawn and dusk. They lay eggs in standing water – like irrigated fields, old tires or puddles of water standing for more than a few days.
Protect Yourself: Remember the Four D’s
Greeley’s Mosquito Program
Greeley’s Stormwater Division runs the city’s mosquito program. Since 2022, the city has worked with Vector Disease Control International (VDCI) to help control mosquitoes. This company sets traps and checks 20 sites in Greeley each week. It also treats water in city-owned parks, ponds and open spaces to eliminate mosquitoes before they hatch.
Lauren Hillmer, Stormwater Quality Administrator in the city’s Public Works and Transportation Department, said residents can help by eliminating standing water around their homes and using mosquito protection.
“We work closely with our contractor to stay on top of any positive West Nile Virus tests of mosquitoes in Greeley,” Hillmer said. “We initiate targeted spraying of neighborhoods the following evening after a positive test exceeds a set threshold.”
The virus is prevalent from May to September when mosquitoes are most abundant, but the risk to humans occurs primarily from August to early September.
The Weld County Health Department publishes data on mosquito testing in Weld County. There were 15 reported human West Nile Virus cases in Weld County in 2024.
To report mosquito issues or to learn more about spraying operations, call the city’s mosquito contractor, VDCI, at 303-428-5908.
Release Date:
Jul 14, 2025