Las Vegas – If at the same time it was thought that mosquitoes could not survive in desert climates, this city is a case study on how wrong it is.
Mosquitoes typically prefer more tropical and humid conditions, but these bite machines have exploded in number throughout the Las Vegas Valley in recent years due to a series of changes.
A mixture of urban development, climate change, Insecticide resistance and genetic adaptations are creating a more hospitable environment for insects in southern Nevada.
Las Vegas is barely alone in their battle against the annoying insects. Warmer temperatures and changing climate patterns are expanding the geographical range in which mosquitoes live and reproduce. In many ways, what is happening here is to play in the southwest desert and beyond.
Mosquitoes have brought with them not only the discomfort of insect bites, but also the main threat of diseases transmitted by mosquitoes, such as dengue fever and the western Nile virus to Las Vegas and the rest of Clark county.
He also caught the off guard.
“People are not wrong because mosquitoes should not really prosper in desert conditions, but it is clear that the particular set of species that we have in Clark County has adapted to local ecology,” said Louisa Messenger, an assistant professor in the Department of Environmental and Global Health of the University of Nevada, Las Vegas.
‘A tick time bomb’
The species that have been strengthened in Clark County include Culex mosquitoes, which can transport Western Nile virus, and Aedes Aegypti mosquitoes, the main dengue dispersators. In addition, Messenger and their colleagues in UNLV have discovered that mosquitoes in Las Vegas are becoming resistant to insecticides, a great public health risk in a city based on tourism.
“It’s a bit of a time bomb,” said Messenger.
For some time he has been worried about how vulnerable it is Las Vegas to the diseases transmitted by mosquitoes. In particular, dengue has been emerging in North America and South America, with more than 13 million cases registered on the continents in 2024, according to the centers for disease control and prevention.
“In Las Vegas, we have more than 48 million visitors who come through our doors every year on the entire planet,” Messenger said. “You only need a couple of mosquito bites to start local transmission.”
Last year, there were 26 reported cases of Western Nile virus in humans in Las Vegas, according to the Southern Nevada Health District, following the largest outbreak of the city of 43 cases in 2019. However, in 2024, in 2024, scientists still found a record number of mosquitoes that gave positive for the virus in and the city, which suggests that the risk was very conceived.
This year, the Department of Public Health has not identified any human cases so far, even when mosquitoes have positive for the virus in certain postal codes. Messenger said that it is not well understood what specific factors combined outbreaks in some years and not in others.
“We see these overlapping factors, but they are quite difficult to disarm it,” he said. “All we can say with certainty is that we have these years of bumper and these zero years, and are difficult to predict.”
The Southern Nevada Health District has been carrying out a mosquito surveillance in the region since 2004. Its meticulous records show which mosquito species are present in the Las Vegas Valley year after year and where these flying insects have tested positive for diseases.
One of the most surprising trends in the data was the explosive growth of Aedes Aegypti mosquitoes, which first identified in Las Vegas in 2017, said Vivek Raman, environmental health supervisor of the Health District of Southern Nevada.
The ‘implacable biters’ are spreading
“In 2017, this mosquito was found in just a few postal codes,” said Raman, who supervises the Mosquito Surveillance Program of the Health District. “A few years later, there were six postal codes. Then 12 postal codes, then perhaps 20, and is now in 48 different postal codes throughout the valley.”
In addition to being able to spread dengue, these insects are a great discomfort.
“Aedes Aegypti are very aggressive diurnal mosquitoes,” Raman said. “They are just relentless Biters.”
Unlike CULEX mosquitoes, which prefer the raising of almost larger water, such as non -arrested pools, sewers or detention basins, Aedes aegypti tends to reproduce in much less deep stagnant water.
“One of the reasons why they are spreading so fast is that the mosquito can place its eggs in small containers, as if the rain fills the toy or tires of a child or a wheelbarrow,” Raman said. “All that is needed is a couple of inches of water.”
Urban development in Las Vegas has also stimulated without realizing the spread of mosquitoes in the city. The golf courses, the lakes manufactured by humans and other forms of artificial irrigation have made this position advanced in the Nevada desert a welcome home for mosquitoes, according to Messenger.
It is likely that climate change is also a factor, and is an active research area for Messenger and other scientists. The warmer temperatures are expanding the range of geographies for mosquitoes worldwide. A warmer atmosphere can also contain more moisture, which increases moisture and rain, both friendly conditions with mosquitoes.
In Las Vegas, the way in which the interaction between local environmental factors and changing climatic trends affects mosquito populations is less good, but implications are essential.
“Las Vegas is a kind of case study for how climate change will be seen in other parts of the world,” Messenger said. “We are seeing record temperatures, we are becoming much more arid, the precipitation is becoming much more aberrant and unpredictable. Thus large parts of the world will be seen in the next 15 to 25 years.”
It remains to be seen what that means for mosquitoes in the city, but the problem so far shows signs of deceleration.
The Health District of South Nevada makes a public scope on how to identify and protect against mosquito reproduction sites in homes and their surroundings, and how to prevent mosquito bites. But, control the number of mosquitoes in the city, and thus control the public health risk, will require a coordinated effort of the local government, Messenger said. Currently, there is not one in Las Vegas.
“You have private pest companies that people can ask for severe infestations, you have some work around wetlands, but what we don’t have, that many other jurisdictions have, is a centralized and coordinated reduction,” said Messenger.
This lack of coordination has turned out that mosquito populations accumulate resistance to insecticides, he added. A centralized effort could evaluate which chemicals are safe to use, particularly around humans, and monitor insecticides and pesticides to prevent mosquitoes from accumulating immunity.
In the coming years, Messenger said, prevention and control will be key to protecting the residents of Las Vegas and their many visitors around the world.
“The conclusion is that this is completely preventable,” he said. “No one in southern Nevada, in Clark County, should be bitten by mosquitoes and get any type of virus.”
