Las Vegas is famous for its hot summers, flashy casinos, and endless entertainment. However, the summer heat also brings mosquitoes that can put a damper on enjoying the outdoors. Mosquito season in Las Vegas can start as early as March and last through October, with peak activity from May to September. Understanding when mosquitoes are most prevalent and how to avoid bites is key to fully enjoying the Las Vegas valley during the warm weather months.
Overview of Mosquito Activity in Las Vegas
According to Vivek Raman, an environmental health supervisor with the Southern Nevada Health District (SNHD), mosquito surveillance typically begins in March each year. The SNHD monitors mosquito activity through a network of traps located across Clark County and the Las Vegas valley. The traps help pinpoint when and where mosquitoes become active so prevention and control measures can be implemented.
Raman said mosquito activity starts to increase in May, with numbers rising through the hot summer months. July and August are usually the peak of mosquito season in Las Vegas when the species best suited for the climate, including Aedes aegypti, thrive and reproduce rapidly. Aedes aegypti mosquitoes are most active during the day and efficient at transmitting viruses like West Nile. Mosquito numbers then begin to drop off after September, though activity can continue into October depending on weather conditions.
“There’s always a baseline level of mosquito activity, but it really starts picking up in the spring and summer when warmer temperatures allow populations to boom,” Raman said. “So May through September is when residents need to be most vigilant about mosquito bites.”
Mosquito Breeding Habitats in Las Vegas
According to the SNHD, the Aedes aegypti mosquito that commonly spreads viruses is present year-round in Southern Nevada. But what allows it to reach high numbers during warmer months?
Raman said these mosquitoes prefer urban and suburban areas. They lay their eggs in small containers that hold standing water – things like plant saucers, old tires, tin cans, and toys left outside. “Anywhere that stagnant water collects can act as a breeding ground,” he said.
Other common backyard sources include pet dishes, clogged rain gutters, receptacles under potted plants, and even water feature or fountain pumps if not properly maintained. Swimming pools that are not cared for or circulating water can also produce large mosquito populations.
“Eliminating standing water is key to reducing mosquito breeding on your property,” Raman said. “Residents should survey their yard for any containers or areas where water can collect and drain or dump them out weekly.”
He also recommended changing water in pet bowls, bird baths, and livestock troughs at least twice a week. Keeping grass cut short and shrubs pruned away from the home can also help eliminate resting spots for the day-biting Aedes mosquito.
Monitoring Mosquito Activity and West Nile Risk
Mario Vitale, an environmental health supervisor with SNHD, oversees the county’s mosquito surveillance program. He said their traps and testing procedures allow them to track both total mosquito activity and any viruses present.
“We monitor mosquito abundance at each trap location to guide control efforts,” Vitale said. “Testing also identifies if West Nile or other viruses are circulating so we can alert the public about risk levels.”
The SNHD currently monitors 60 trap sites across Clark County, including in Las Vegas, Henderson, North Las Vegas, Laughlin, Boulder City, Mesquite, and other regions. The traps are checked weekly starting in April and the mosquitoes collected are tested at SNHD’s public health laboratory.
Vitale said if West Nile is detected in mosquitoes at a certain trap location, extra spraying and prevention education is done in the surrounding neighborhood. Residents can contact the mosquito surveillance program at 702-759-1633 to find out about mosquito activity levels and virus alerts for their zip code.
Protecting Yourself from Mosquito Bites
The most effective way to avoid mosquito-borne illnesses like West Nile is to prevent bites. Vivek Raman recommends taking the following precautions anytime you are outdoors:
- Use an EPA registered insect repellent. Raman said products containing DEET, picaridin, IR3535 or oil of lemon eucalyptus are most effective. Follow instructions and reapply as needed.
- Wear long sleeves and pants when possible or apply repellent to exposed skin. Mosquitoes can bite through thin fabrics.
- Limit outdoor time at dawn and dusk when mosquitoes are most active.
- Make sure window and door screens are in good repair to keep mosquitoes out.
- Don’t let standing water accumulate in your yard or neighborhood. Report unmaintained pools or stagnant ponds to SNHD.
Raman said mosquito prevention should be taken seriously because a single bite can transmit West Nile or other viruses. “Even with low numbers of cases, the consequences of contracting one of these diseases can be severe or even fatal,” he cautioned.
In 2017, Clark County declared a West Nile virus outbreak with over 220 confirmed infections. While case counts have dropped since, randomized testing shows the virus continues to circulate. West Nile can cause fever, headache, and muscle weakness. Severe cases may lead to neurological issues, paralysis, or death.
There is currently no vaccine for West Nile virus. The SNHD encourages the public to use repellent, wear protective clothing, and eliminate standing water to prevent infection.
Typical Mosquito Season Timeline in Las Vegas
While weather conditions can cause some variability year to year, following is the typical timeline for mosquito activity and virus risk in the Las Vegas valley:
Early March: SNHD begins placing mosquito traps and surveillance across Clark County. Limited activity involves overwintering Culex species that transmit West Nile virus.
April: Warming temperatures allow breeding and greater mosquito activity, though still low overall. SNHD monitors traps for population growth.
May: Marked increase in mosquito complaints and numbers caught in traps, including Aedes aegypti. Monitor traps weekly and begin targeted spraying if virus found.
June: Hot and dry conditions limit some water sources but mosquito activity remains high. West Nile typically begins circulating in mosquitoes and bird populations.
July/August: The hottest summer months see peak mosquito activity and biggest increase in West Nile risk. Highest need for repellent use and draining standing water.
September: Cooling temperatures and shorter days cause a decline in mosquito populations, though West Nile threat continues. Avoid peak dusk times and use repellent.
October: Hard freezes reduce most mosquito activity, but populations can persist in sheltered areas. First trap collections may show West Nile again present.
November to February: Colder weather keeps mosquitoes dormant until spring. SNHD discontinues regular trapping but may test mosquitoes overwintering in sheltered spots.
Long-term Mosquito Control Efforts
Christopher Bramley, an environmental health supervisor with SNHD, said they also initiate mosquito control projects to reduce breeding long-term. This includes improving drainage systems and modifying neglected pools and ponds by introducing fish that eat mosquito larvae.
“We try to alter habitats so they no longer support mosquito breeding,” Bramley said. “This takes a coordinated effort with businesses, homeowners, and government agencies.”
He said one success story is the Wetlands Park area. Excess vegetation and standing water used to make it a big source of mosquitoes. SNHD worked to enhance water circulation and trim back plants to reduce ideal mosquito habitats.
“Over time, the diversity of bird species and other wildlife improved while the mosquito burden was drastically reduced,” Bramley said.
He encourages anyone noticing areas of consistent standing water or heavy mosquito infestations on public or private property to report them to SNHD’s Vector Control program at 702-759-1633. Getting these sites modified to stop mosquito breeding helps the whole community.
The ideal weather and urban environment of Las Vegas means that mosquitoes are a fact of life during warmer months. While there is always a low level of activity, numbers surge starting in May and remain high through September. Peak mosquito season also comes with increased risk of contracting West Nile virus or other diseases from mosquito bites.
By draining standing water, using repellents, and avoiding peak times, Las Vegas residents can still fully enjoy the outdoors. Coordinated surveillance, control, and public education by agencies like the SNHD also help manage the nuisance and public health issues caused by mosquitoes.
Taking simple prevention measures and being aware of the mosquito season timeline can help you fight the bite in Las Vegas! Reach out to SNHD if you have any concerns about mosquitoes in your area.