Las Vegas – Once believed to be inhospitable for mosquitoes, this city proves the opposite is true.

While these pests typically thrive in tropical, humid environments, their population has surged in the Las Vegas Valley in recent years due to various factors.

Urban development, climate change, insecticide resistance, and genetic adaptation have all created a more conducive environment for these insects in southern Nevada.

Las Vegas isn’t alone in its struggle against these pests; warm temperatures and shifting weather patterns are extending the habitats where mosquitoes can breed across the southwestern United States and beyond.

Besides being a nuisance, mosquitoes also pose a significant risk of mosquito-borne diseases like dengue and West Nile virus to Las Vegas and Clark County.

This situation has taken many by surprise.

“It’s not incorrect to say that mosquitoes shouldn’t thrive in desert conditions, but it’s evident that certain species present in Clark County have adapted to the local environment.”

“Time Bomb”

Among the species found in Clark County are the Culex mosquito, known to carry West Nile virus, and the Aedes aegypti mosquito, a primary transmitter of dengue. Researchers at UNLV have also identified resistance to insecticides in local mosquito populations.

According to Messenger, “It’s a time bomb that’s been ticking for a while.”

She is particularly concerned about Las Vegas’s vulnerability to mosquito-borne diseases. Dengue fever cases are on the rise in North and South America, with more than 13 million cases reported across the continent in 2024, as noted by the CDC.

“Las Vegas receives over 48 million visitors from around the world every year,” Messenger remarked. “Local transmission can start with just a single mosquito bite.”

Last year, 26 cases of West Nile virus were reported in the city. According to the Southern Nevada Health District, 2019 had the largest outbreak, but a record number of mosquitoes tested positive for the virus in and around Las Vegas in 2024.

While some mosquitoes have tested positive for the virus this year, the public health department has not identified any human cases so far. Messenger indicated that specific factors from previous years complicate their understanding of the situation.

“We see many overlapping factors, but it’s challenging to isolate them,” she said. “There are these bumper years and then none at all, making predictions difficult.”

The Southern Nevada Health District has been monitoring mosquitoes since 2004, keeping detailed records that show the types of mosquitoes present in the Las Vegas Valley and their associated diseases.

One striking trend has been the rapid increase in Aedes aegypti mosquitoes, first spotted in Las Vegas in 2017, according to Vivek Raman, an environmental health supervisor for the Southern Nevada Health District.

“Relentless Biting” Spreads

“In 2017, we found this mosquito in just a few zip codes,” Raman noted. “A few years later, it expanded to six, then twelve, and now it has appeared in 48 different zip codes throughout the valley.”

These insects not only spread dengue fever but are also a significant nuisance.

“The Aedes aegypti is an extremely aggressive daytime mosquito,” Raman explained. “Their bites are relentless.”

Unlike Culex mosquitoes, they prefer to breed near larger water sources, such as neglected swimming pools, dark corners, and detention ponds.

“One of the reasons for their rapid spread is their ability to lay eggs in small containers, like children’s toys, tires, or wheelbarrows,” Raman added. “Just a few inches of water are enough.”

Urban development in Las Vegas has also redirected mosquito populations. According to Messenger, golf courses, artificial lakes, and other irrigation methods have transformed the Nevada desert into an inviting habitat for mosquitoes.

Climate change is another contributing factor and is under active investigation by Messenger and other scientists. Higher temperatures are broadening the areas where mosquitoes can thrive. Warm air can hold more moisture, leading to increased humidity and rainfall—all ideal for mosquito breeding.

While it’s not entirely clear how local environmental aspects interact with shifting climate trends to impact mosquito populations, the potential consequences are significant.

“Las Vegas serves as a case study for how climate change may manifest in other regions globally,” Messenger stated. “We’re witnessing record temperatures and increasingly erratic precipitation patterns. This is predictive of what much of the world may look like in the next 15-25 years.”

The implications for urban mosquito populations remain uncertain, but current trends show no signs of abating.

Health districts in southern Nevada are engaging in public outreach to help residents identify and manage mosquito breeding sites around their homes, along with strategies to prevent bites. To effectively address mosquito populations and associated public health risks, comprehensive efforts from local governments are essential, according to Messenger. Right now, this level of coordination is lacking in Las Vegas.

“We have private pest control companies, and some work is being done around wetlands, but what we lack is a centralized and coordinated reduction effort across multiple jurisdictions,” Messenger explained.

That absence of coordinated action has contributed to mosquito populations becoming increasingly resistant to insecticides. Ongoing monitoring is necessary to determine which chemicals are safe to use around humans and to evaluate the effectiveness of insecticides and pesticides to prevent mosquitoes from developing immunity.

Looking ahead, Messenger emphasized that prevention and control will be vital to protecting both Las Vegas residents and the many visitors from around the globe.

“Ultimately, this situation is entirely preventable,” she asserted. “No one in southern Nevada, including Clark County, should suffer mosquito bites or risk contracting any virus.”