Mosquitoes are present in the Las Vegas Valley, despite the arid Mojave Desert environment. While the desert climate does not naturally foster their survival, human activity and urban development have created microclimates where these insects flourish. Their presence, particularly in Clark County, is a growing public health concern requiring management of mosquito-borne illnesses.
The Reality of Mosquitoes in Las Vegas
Mosquitoes survive in the Las Vegas Valley despite the harsh desert heat primarily because of the extensive network of artificial water sources constructed by humans. These water features provide the standing water necessary for the mosquito life cycle. Urban development, including irrigated lawns, golf courses, and ornamental ponds, acts as a continuous source of moisture that supports mosquito breeding throughout the warmer months.
The insects utilize everything from neglected swimming pools, often called “green pools,” to small containers of water left outdoors. The invasive species Aedes aegypti only requires a minimal amount of water, such as that found in a bottle cap or a plant saucer, to lay its eggs.
Specific Species and Local Disease Risks
The Southern Nevada Health District (SNHD) primarily monitors two significant mosquito vectors in Clark County: Culex species and the invasive Aedes aegypti. Culex mosquitoes are the main carriers of West Nile Virus (WNV) and are responsible for maintaining the virus in local bird populations before it is transmitted to humans. They typically bite during the cooler hours of dawn and dusk and lay their eggs in larger, stagnant water bodies like unmaintained swimming pools or marshy areas.
West Nile Virus is considered endemic in Clark County during the mosquito season, which generally runs from April to November. While many people infected with WNV experience no symptoms, a small percentage can develop a severe neuroinvasive illness, such as encephalitis or meningitis. In 2019, Clark County experienced a significant outbreak with 43 confirmed human cases, and in 2023, two human cases were reported.
The other mosquito of concern is Aedes aegypti, which was first detected in the area in 2017 and has since spread rapidly across dozens of zip codes. This species is a highly aggressive daytime biter that prefers feeding on people and is well-adapted to urban settings, breeding in small water-filled containers near homes. While it is known globally for transmitting Zika, Dengue, and Chikungunya viruses, local transmission of these illnesses has not been established in Southern Nevada, but the potential risk remains.
Official Control and Surveillance Efforts
Mosquito management in Southern Nevada is primarily handled by the Southern Nevada Health District’s (SNHD) Mosquito Disease Surveillance Program. This program is responsible for monitoring mosquito populations and testing for arboviruses across the six jurisdictions of Clark County. Staff members set thousands of specialized traps, including CDC Light traps, Gravid traps, and BG Sentinel traps, to collect and identify the types of mosquitoes present and their disease status.
The captured mosquitoes are submitted to the Southern Nevada Public Health Laboratory to be tested for viruses like West Nile Virus, St. Louis Encephalitis, and Western Equine Encephalitis. This surveillance data is then used to inform the public and guide local municipalities on where to focus their control measures. While SNHD is a surveillance agency and does not perform broad control measures itself, it refers identified breeding sources, such as green swimming pools, to local code enforcement and public works departments for abatement.
The SNHD also runs public education campaigns, such as the “Fight the Bite” initiative, to inform residents about prevention and the importance of eliminating standing water. The public is encouraged to report increased mosquito activity or potential breeding sites to the Health District’s surveillance program.
Personal Protection Strategies
The most effective action is to eliminate all sources of standing water around a property, as mosquitoes only need small amounts of water to lay their eggs. This includes frequently emptying containers such as:
- Plant saucers
- Buckets
- Pet dishes
- Children’s toys
- Ensuring that rain gutters are not clogged
For personal protection, using an insect repellent registered by the Environmental Protection Agency (EPA) is highly recommended. Effective active ingredients include:
- DEET
- Picaridin
- Oil of Lemon Eucalyptus
- IR3535
Applying repellent to exposed skin offers a reliable barrier against bites, especially during the peak activity hours for different species. Wearing loose-fitting clothing that covers the arms and legs also minimizes the amount of skin available for mosquitoes to bite. Since Culex mosquitoes are most active at dawn and dusk and Aedes aegypti are aggressive daytime biters, wearing protective clothing during all hours spent outdoors is prudent. Additionally, ensuring all window and door screens are in good condition prevents mosquitoes from entering homes and biting people while they sleep.