Most West Nile cases in Colorado happen between July and September, though mosquitoes can live until the first snow or hard freeze.

DENVER ( KDVR) — The first trace of the West Nile virus this season was found in Denver through a positive mosquito sample. On Thursday, the Denver Department of Public Health & Environment announced that the virus was found through routine mosquito sample testing. This marks the first detection of the season for the city.

This week, a sample of the mosquito population in Larimer County in Northern Colorado tested positive for West Nile virus.