The Southern Nevada Health District is starting its annual mosquito surveillance activities about a month earlier than usual, citing warmer-than-average temperatures and recent rainfall across Clark County.

Staff are setting mosquito traps throughout the Las Vegas Valley as part of the Health District’s Mosquito Disease Surveillance Program, officials said today in a new release.

Officials say the early start allows them to monitor mosquito populations, identify species and detect signs of mosquito-borne viruses before peak mosquito season arrives.

Traps are being placed in parks, wash channels, wetlands, residential neighborhoods and other potential breeding sites. Mosquitoes collected are sorted and cataloged by species and location. Samples are then sent to the Southern Nevada Public Health Laboratory to be tested for arboviruses, including West Nile virus.

“Starting mosquito surveillance one month early gives us a critical head start,” said Dr. Cassius Lockett, district health officer in a news release. “With warmer temperatures and the potential for standing water from recent rains, mosquitoes can begin breeding sooner than usual. Taking action now allows us to detect virus activity early and respond quickly. Mosquito prevention starts at home, and we encourage residents to eliminate standing water before mosquito populations increase.”

West Nile virus activity in Clark County has fluctuated in recent years. 

In 2024, 12 nonneuroinvasive cases and 14 neuroinvasive cases — infections that affect the brain or spinal cord — were reported in the county. No human cases were reported in 2025.

Health officials are particularly urging residents to take precautions against Aedes aegypti, an invasive species capable of transmitting Zika, dengue, yellow fever and chikungunya. Unlike most mosquitoes, Aedes aegypti are aggressive daytime biters that prefer feeding on people and breed in small water-collecting containers such as plant saucers, buckets, children’s toys and bottle caps.

The Health District’s “Fight the Bite” campaign is asking residents to eliminate standing water around their homes, use EPA-registered insect repellent, wear protective clothing, report mosquito activity to the surveillance program at 702-759-1633, and report green pools to their local code enforcement agency.

Additional prevention resources are available here.