It is important to remember the risk of becoming ill from one mosquito bite is low. The easiest and best way to avoid West Nile virus is to prevent mosquito bites and eliminate areas of standing water around your home.

  • Repellents: When you are outdoors, use insect repellents containing DEET, Picaridin, or oil of lemon eucalyptus. Follow the directions on the package.For more information on insect repellents and how to apply them safely, see the Insect Repellent page.
  • Clothing: Wear pants and long-sleeved shirts when outdoors and spray repellent on clothes and exposed areas of skin. Light colored clothing can help you see mosquitoes that land on you.
  • Time of Day: Avoid spending time outside when mosquitoes are most active, notably at dawn and dusk (the first two hours after sunset).
  • Household: Make sure doors and windows have tight-fitting screens without tears or holes.
  • Infants: If you are outdoors in a mosquito infested area, place mosquito netting over infant carriers.
  • Sleeping: Use mosquito netting when sleeping outdoors or in an unscreened structure.
  • Standing Water: Prevent mosquito breeding by eliminating areas of standing and/or stagnant water including unmaintained swimming pools.

Mosquito Breeding Prevention

The immature stages of the mosquito (egg, larva, pupa) develop in standing water. It takes seven to ten days from the time a mosquito lays her eggs, until 100 to 400 larvae (wrigglers) begin their life, possibly in your backyard. The size of the container of water doesn’t matter, as mosquito larvae and pupae are small.

Where to Look and What to Do

At Home

If you need assistance or have questions about a mosquito breeding source around your home, contact your local code enforcement agency.

Concrete or Above Ground Swimming Pools

  • Chlorine will not kill mosquito larvae.
  • If pool cover is used, keep it tightly sealed.
  • Remove rain water from top of pool cover.
  • Stock unused or “out-of-order” pools with mosquito fish.

Plastic Wading Pools

  • Change water every week.
  • Store indoors when not in use or on vacation

Ornamental Ponds

  • Aerate (fountain, bubbler, etc.) ornamental pools, ponds, etc. or stock them with mosquito eating fish.
  • Stock with fish.
  • Avoid spraying with garden insect sprays.
  • Remove leaves and thin out plants.
  • Keep water level up.
  • Screen inlet of recirculation pump.
  • Transfer fish to glass bowl when cleaning pond because chlorine kills fish.
  • If pond is no longer desired, break holes in the bottom and fill with dirt or sand.


  • Prevent accumulation of sprinkler or rainwater.
  • Store small boats upside down or cover to keep out the rain and water from your sprinklers.

Animal Water Troughs

  • Stock large troughs with mosquito fish.
  • Clean small troughs every week.
  • Change the water in pet dishes twice a week.

Containers (cans, jars, barrels, old tires, buckets, tubs, etc.)

  • Remove and dispose of all unused containers that will collect rain water or water from your sprinklers.
  • Home gardeners rooting plant cuttings in vases, buckets, etc. should change water every week.
  • Usable containers should be stacked upside down.
  • Drill drainage holes in tire swings, recycling containers, etc., so water drains out.

Other Sources of Standing Water

  • Under the house
  • Repair leaking plumbing
  • Prevent seepage from garden irrigation
  • Divert storm water away from foundations
  • At drain outlet from air conditioner
  • Keep rain gutters clean and free of debris so water drains properly.

In the Community

Contact your local code enforcement agency if you see any standing or green water in the community, such as:

Natural Sources

  • Marshes
  • Rain pools
  • Ravines

Agricultural Sources

  • Excess irrigation drainage water
  • Water standing in pastures and irrigation ditches

Community or Industrial Sources

  • Wastewater treatment plants
  • Storm drainage channels
  • Street drains
  • Improperly drained golf courses
  • Abandoned tires
  • Green fountains or pools

Updated on: August 23, 2019

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