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Shaku Nair, Dawn H. Gouge and Shujuan Li
Department of Entomology, University of Arizona
Mosquito activity typically spikes from April through October in Arizona, with populations of potential pathogen vectors surging during the summer monsoon season (July through September) when heavy rains create the standing water needed for them to breed. Warm winter months allow some mosquitoes to remain active year-round, especially in low-elevation areas like the Phoenix metro.
Figure 1. Be aware of mosquito activity as summer rolls in! Photo: famveldman, Adobe Stock.
Not only are mosquitoes annoying, biting pests (Figure 1), they can also cause a variety of health problems due to their ability to transfer (vector) viruses and other disease-causing pathogens.
As of July 21, 2026, AZ has the highest number of West Nile case nationally. 91 nationally, of which 55 are in the state of Arizona, most in state occurring in Maricopa County.
Humans create a lot of opportunities for mosquitoes to exploit. Many of us have mosquitoes developing in our neighborhood and even in our own backyards. Standing water left from rain or irrigation water will support increasing mosquito populations.
Stagnant water in neglected swimming pools is another ideal habitat for many species, though mosquitoes cannot live in a well-maintained swimming pool. Some important vectors breed in “cryptic” breeding sites, utilizing very small
amounts of water in tree-holes, artificial containers and even in leaf axils of plants. An understanding about mosquito biology and behavior will help you manage mosquitoes in your environment, and related disease risks.
The Mosquito Life Cycle
Figure 2. Generalized mosquito life cycle. Image: Aldona, Adobe Stock.
All mosquitoes must have water to complete their life cycle, although some species require very little water and can develop in a thin moisture film. The mosquito life cycle is an example of complete metamorphosis. There are four distinct stages in the life of a mosquito: egg, larva (aquatic feeders), pupa (aquatic non-feeders) and adult (Figure 2). Female mosquitoes usually lay eggs a few days after acquiring a blood meal. Depending on the species the eggs may be laid singly or in groups (rafts). The eggs are laid on the surface of water, on the sides of containers, or on damp soil. The eggs hatch into little larvae or “wrigglers” that swim in the water and feed on microorganisms or decaying organic matter. The larvae go through four growth stages called instars, in which they grow in size, before reaching the nonfeeding pupal stage. They must come to the surface of the water to breath (with the exception of a few specialized mosquitoes). Mosquito larvae have a siphon at the tail end of the body which allows them to breathe by penetrating the surface of the water to access air directly. After the fourth larval instar, the pupa are formed. They are often called “tumblers”, as they rotate within the water column. Similar to the larvae, mosquito pupae breathe by using their respiratory “trumpets” to draw air from the atmosphere directly through the surface of the water. The pupal stage is normally quite short (1-2 days), after which the adult mosquito emerges. The immature stages of mosquitoes are sometimes confused with tadpoles or leeches, and aquatic non-mosquito insect larvae are sometimes mistaken for mosquito larvae. If you are uncertain what you have found and wish to submit specimens for identification, please reach out to your local county cooperative extension office or vector control department.
The last stage of development namely, the adult, is the only stage involved in disease transmission, and the most difficult to manage. Adults fly and adult females bite to take blood meals. Male and female mosquitoes also feed on flower nectar. Male mosquitoes look similar to females but can be identified by their feathery antennae. The long hairs on their antennae help them to locate flying females. Male mosquitoes travel shorter distances from breeding sites than female mosquitoes. So if you find male mosquitoes, the breeding site is likely nearby.
Key Mosquito Species in Arizona
Although there are about 180 species of mosquitoes in the U.S. and more than 40 in Arizona, only a few are problems for residents. Of these, the Culex and Aedes mosquitoes
are of greatest concern because of the disease-causing pathogens they vector. Here are the mosquito species of concern:
Managing Mosquitoes
Many local governmental and other agencies work year-round on mosquito surveillance and abatement, trapping and testing mosquitoes, monitoring human and animal cases of mosquito-borne diseases, watching
for new species, and providing information for residents, travelers and healthcare providers. Check out the Maricopa County Environmental Services page on mosquito management https://www.maricopa.gov/5811/Fight-the-Bite.
Image source: https://www.maricopa.gov/5811/Fight-the-Bite#YouDo
The campaign titled “Fight the Bite” urges residents and visitors to the site to Remember The Four R’s.
The site provides an Online Mosquito Toolkit https://www.maricopa.gov/5907/Mosquito-Toolkit that provides ready-to-use information to share with your community,
coworkers, and others that empowers them to take action to prevent mosquito bites.
What Can Residents Do To Help Reduce Mosquitoes?
Reducing mosquitoes and related illness
Figure 3. Mosquitoes will use any available standing water as a breeding habitat, and some can be as
small as a bottle cap (AI Generated). Image: Chandana, Adobe Stock.
The most effective strategy for mosquito management in communities in general is prevention. The best way to prevent
mosquito-borne diseases is to eliminate their breeding sites in the first place (Figure 3).
Here are some tips on what you can do to manage mosquitoes and eliminate mosquito breeding sites around you.
Eliminate standing water.
Figure 4. Bird baths can be great mosquito-breeding habitats if not maintained regularly.
Image: nicholas_rexrode, Adobe Stock.
Remove unnecessary clutter.
Pets and livestock.
Preventing mosquitoes indoors.
Figure 5. Aedes aegypti eggs on lucky bamboo (see inset circled in orange).
Photo: Greater Los Angeles County Vector Control District.
Protect yourself.
When outdoors, consider the following safety tips:
Use protective clothing when exposure to mosquitoes cannot be avoided.
Properly apply insect repellent even if you are outside for just a short period of time, and share your insect repellent with those around you.
Type of repellents: According to the Centers for Disease Control and Prevention (CDC) when used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women. The following are active ingredients in EPA-registered skin-applied insect repellents:
Reactions to DEET are uncommon, but picaridin products are less likely to trigger dermal reactions when used repeatedly over extended periods of time.
More information about mosquito and tick repellents can be found at: https://extension.arizona.edu/sites/extension. arizona.edu/files/pubs/az1761-2018.pdf
After-Bite Care
Check with your medical care professional and ask what would be the best option for you if you need itch relief.
Check out a variety of resources on mosquitoes and their management, in different formats from the University of Arizona Cooperative Extension. https://extension.arizona.edu/search?keys=mosquitoes
Check out these resources from the California Department of Pesticide Regulation for mosquito prevention at schools: https://www.cdpr.ca.gov/wp-content/uploads/2024/11/mosquito_ipm_at_schools.pdf
“Why are there mosquitoes in the world?” “What is their purpose, other than making our lives miserable?” “Why do mosquitoes even exist?” If you have any of these questions or more, you are certainly not alone! While it may seem impossible, mosquitoes actually play some vital ecological roles, acting as fundamental food sources for various predators, aiding plant pollination, and recycling aquatic nutrients. Although individual mosquitoes are tiny, their immense biomass sustains wildlife populations worldwide. To put “immense biomass” into perspective, consider this: Scientists estimate that in certain regions, such as Alaska, mosquito biomass can reach up to 96 million pounds, providing a massive, reliable seasonal energy source for migrating birds and other local wildlife.
Here are some examples of ecological contributions made by mosquitoes:
If you are interested in this aspect of mosquitoes, check out these blog articles:
https://blog.nwf.org/2020/09/what-purpose-do-mosquitoes-serve/
https://theconversation.com/the-bizarre-and-ecologically-important-hidden-lives-of-mosquitoes-127599
Photo by Kyle Kelly, Queen Creek Parks and Rec.
Answer: Leaf-footed bugs.
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What’s Bugging You? First Friday Events (New York State IPM Program)
Fridays | 12:00 pm. – 12:30 p.m. EDT | Zoom | Free but registration required.
In this monthly virtual series, we explore timely topics to help you use integrated pest management (IPM) to avoid pest problems and promote a healthy environment where you live, work, learn and play. What is IPM? It's a wholistic approach that uses different tools and practices to not only reduce pest problems, but to also address the reasons why pests are there in the first place. Each month, our speakers will share practical information about how you can use IPM. Register for upcoming events.
What’s Bugging You First Friday events are also available in Spanish. Individuals interested in these events can find more information on this website: https://cals.cornell.edu/new-york-state-integrated-pest-management/outreach-education/events/whats-bugging-you-webinars/conozca-su-plagaUrban and Community IPM Webinars (Host: University of California)
UC Statewide IPM Program Urban and Community webinar series is held the third Thursday of every month to teach about pest identification, prevention and management around the home and garden. This series is free but advanced registration is required. Dates and topics below, all begin at noon Pacific. https://ucanr.edu/sites/ucipm-community-webinars/
To view previous University of Arizona newsletters, visit: https://acis.cals.arizona.edu/community-ipm/home-and-school-ipm-newsletters.
https://uarizona.co1.qualtrics.com/jfe/form/SV_cMhZ82JodDKJgCa
This material is in part funded by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2024-70006-43563 that provides Extension IPM funding to the University of Arizona. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the U.S. Department of Agriculture or those of other funders.
We respectfully acknowledge the University of Arizona is on the land and territories of Indigenous peoples. Today, Arizona is home to 22 federally recognized tribes, with Tucson being home to the O’odham and the Yaqui. Committed to diversity and inclusion, the University strives to build sustainable relationships with sovereign Native Nations and Indigenous communities through education offerings, partnerships, and community service.
