Division of Environmental Health

CONTACT INFORMATION: Our Environmental Health Services office at 10777 Main Street in Fairfax is open during regular business hours 8 a.m. - 4:30 p.m., Monday - Friday. Clinic services are not offered at this location.
703-246-2201 TTY 711
10777 Main Street
Fairfax, VA 22030
Pieter A. Sheehan, REHS
Director, Division of Environmental Health

Mosquito Prevention

Mosquitoes biting you in your yard? Request a FREE yard inspection from the Health Department using our Mosquito Inspection Request form. One of our staff can help identify potential mosquito breeding sites in your yard and provide tips on mosquito prevention.

Not only are mosquitoes a nuisance, they are capable of transmitting diseases, including malaria, dengue, yellow fever, Chikungunya, West Nile Virus and Zika virus. In Fairfax County, West Nile Virus poses the greatest risk. It is important to know how to help control the mosquito population where you live and how to protect yourself from mosquito bites. By protecting yourself from mosquitoes and mosquito bites, you can prevent mosquito-borne disease.

Mosquito Biology

Mosquitoes have a complex life cycle with many changes in form. Female mosquitoes lay their eggs directly on the water surface or in an area that will be flooded or covered with water. A larva hatches out of an egg. The mosquito larva grows in the water and feeds on microorganisms and organic material in the water. It sheds its skin three times and has a total of four larval stages. This usually takes about a week. After the fourth larval stage, the mosquito larva turns into pupa. In the pupal stage, which is still in the water, the mosquito is not eating, but changing into the adult mosquito. This transformation occurs within a couple of days. After the pupal stage, the mosquito emerges as the more familiar flying adult mosquito. Although there are both male and female adult mosquitoes, only the female mosquitoes bite. The female mosquitoes use the blood to help develop eggs and provide nutrition to the developing embryos.

Mosquito Behavior

Mosquitoes need standing water to develop. By eliminating standing water in containers from around your yard once a week, you can help reduce the number of mosquitoes in your yard.

Mosquitoes are most active at dusk and dawn. The majority of mosquito species are active at night, but the Asian Tiger mosquito (Aedes albopictus) is also active during the day.

Mosquito Control

What the County Does

The Health Department has a robust mosquito management program that includes monitoring, source reduction (elimination of standing water), larviciding (killing mosquito larvae), community education and outreach. Traps are set on a weekly basis during mosquito season to collect adult mosquitoes. Many of these mosquitoes are tested for West Nile virus and Zika virus. 

County-maintained stormwater dry ponds are routinely inspected by Health Department staff for mosquito breeding during the months of April through October. These sites are treated with larvicides to control immature mosquitoes before they become flying adults. 

Routine monitoring activities may indicate the need for additional mosquito control activities. If the risk of disease transmission to humans is high, the County coordinates larval and/or adult mosquito control measures in public areas as necessary. The Health Department does not spray for nuisance mosquitoes. Only under exceptional circumstances will the Health Department spray insecticides to control adult mosquitoes, and in these rare cases, the spray will target only those mosquitoes which transmit disease to humans. All products used by our program are registered for such use by the U.S. Environmental Protection Agency. 

What You Can Do

You can do your part to control mosquitoes around your home and yard by doing the following:

Find out more about the Health Department’s mosquito monitoring activities.

Interested in a yard inspection by one of the health department's environmental health team members to help determine the source of your mosquitos? Request a visit by filling out this form:

Mosquito Bite Prevention

Even if you get rid of most of their breeding ground, mosquitoes can still find you. Here are some tips to Fight the Bite: 

  • Defend yourself: Wear insect repellent
  • Avoid peak times: Stay indoors at dawn and early evening. 
  • Dress right: Wear long, loose and light-colored clothing when outdoors. 
  • Keep them outside: Install, repair or replace screens on both windows and doors.


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