Although Arizona is best known for its dry desert climate, mosquito activity poses an ongoing public health concern in the state. The seasonal monsoon rains, combined with irrigation and urban landscaping practices, create pockets of standing water that serve as breeding grounds for mosquitoes. This is particularly worrisome because certain species in Arizona, such as Culex tarsalis and Aedes aegypti, are known carriers of dangerous viruses including West Nile virus, dengue, and Zika (Arizona Department of Health Services).
Culex species mosquitoes are most active between dusk and dawn. They lay their eggs in standing water such as ponds, puddles, horse troughs, and catch basins. In Arizona, Culex mosquitoes can transmit diseases like West Nile virus and St. Louis encephalitis virus. Because of these risks, it is especially important to avoid mosquito bites through repellent use, protective clothing, and eliminating sources of standing water near homes.
Aedes aegypti mosquitoes also pose a growing concern. They are capable of spreading chikungunya, dengue, yellow fever, and Zika virus. Although none of these viruses are currently found in Arizona, they could be introduced if an infected traveler returned from abroad and was bitten by a local mosquito. For this reason, health officials stress that people should avoid mosquito bites while traveling and for three weeks after returning to help keep these diseases out of Arizona (Arizona Department of Health Services).
In addition to disease-carrying species, Arizona is home to nuisance mosquitoes such as Psorophora columbiae. These “floodwater” mosquitoes do not transmit disease but are aggressive biters. They lay eggs in moist soil that hatch once the area floods, creating sudden bursts of mosquito activity. The best protection against these mosquitoes is insect repellent and wearing long-sleeved shirts and pants.
Arizona is home to 56 identified mosquito species, though experts believe this list is incomplete due to limited surveillance. Some species feed primarily on humans, while others prefer birds, horses, or other animals, raising concerns about both human and animal health. Data and maps from 2015 through 2024 show changing mosquito diversity and distribution across the state, but 2025 data is not yet available (Arizona Department of Health Services, “Mosquitoes of Arizona”). Scientists emphasize that a multifaceted approach is needed for effective mosquito surveillance and control. This includes collaboration between entomologists, epidemiologists, social scientists, wildlife ecologists, and agricultural experts. Such integration would allow public health officials to track changes in mosquito species, identify invasive species, pinpoint populations most at risk, and guide targeted vector control strategies.
Ultimately, addressing mosquito concerns in Arizona requires both government and community action. Public health agencies promote education, mosquito surveillance, and control programs, while residents can reduce breeding habitats and protect themselves during peak mosquito season. Although Arizona’s dry climate limits year-round mosquito activity compared to more humid regions, the presence of disease-carrying species means that risks remain significant and demand ongoing attention.
Works Cited
Arizona Department of Health Services. Mosquito-Borne Diseases in Arizona. Arizona Department of Health Services, 2023.
Links: https://www.azdhs.gov/preparedness/epidemiology-disease-control/mosquito-borne
Centers for Disease Control and Prevention. West Nile Virus in the United States: Guidelines and Data. U.S. Department of Health and Human Services, 2022.
Link: https://www.cdc.gov/westnile
University of Arizona Cooperative Extension. Mosquito Management in Arizona. University of Arizona, 2021.
Link: https://extension.arizona.edu/pubs/mosquito-management-arizona
National Institute of Health. National Library of Medicine. National Center for Biotechnology Information. The Mosquito Fauna of Arizona: Species Composition and Public Health Implications.
https://pubmed.ncbi.nlm.nih.gov/38921147/
