Fight the Bite! Mosquito Season Checklist


Fight the bite!



Don’t grow your own mosquitoes

There are more than 50 species of mosquitoes in California. They can be found everywhere from high mountain meadows to deserts below sea level. Mosquitoes have always been a nuisance, but until recently, they seldom posed a health threat. That changed with the arrival of West Nile virus in California, a disease spread by mosquito bites.

Standing water is the mosquito nursery. Mosquitoes can hatch in a week or less, in as little as a half-inch of water. If you get rid of still or stagnant water at least weekly, you will keep many mosquitoes from breeding and take a big step toward protecting yourself and your family.

Take these steps to make outdoor activities around your home safer and more enjoyable:

  • ANIMALS Dogs and cats can be infected but rarely become ill. They do not spread the virus. West Nile virus is deadly for horses, but a vaccine is available. Many bird species can die or become ill. To protect pet birds indoors, make sure your window and door screens are bug-tight. Cover outdoor cages and aviaries with mosquito netting.
  • BIRDBATHS Clean or hose out weekly.
  • BOATS Empty accumulated water from boats, canoes, and cargo trailers.
  • BTi A natural bacteria that kills mosquito and fly larvae yet is non-toxic to fish and animals when used properly. Kills mosquito larvae developing in water. (See dunks.)
  • CHAINLINK FENCES Water can collect in fence posts. Cap them.
  • CONTAINERS Cover or turn upside down so they won’t hold water. This includes boxes, buckets, cans, cups, jars, and pots.
  • DAWN AND DUSK Time when biting mosquitoes are most active since they avoid the heat of day.
  • DRAINS Keep outdoor drains flowing freely.
  • DUNKS Doughnut-shaped blocks that contain BTi, a pesticide that kills mosquito larvae but is non-toxic to animals and fish. Dunks dissolve slowly in water. Available at hardware and garden stores.
  • GARDEN FURNITURE AND ORNAMENTS Check for nooks and crannies that hold water, and drain or flush weekly.
  • IRRIGATION Keep water from collecting in low-lying areas by not over-irrigating.
  • LANDSCAPING Replace plastic mulch with landscape fabric that prevents weeds yet allows water through.
  • LEAKS Fix faucets, air conditioners and hoses that leak and puddle.
  • LIGHTING Check garden lights. Drain water from inside and off the caps.
  • MOSQUITO FISH These tiny fish chow down on mosquito larvae that have just hatched from eggs. Many vector control agencies will supply mosquito fish without charge to residents to put in ornamental ponds, unused swimming pools, ditches, sumps, water troughs, and similar sites.
  • PET WATER BOWLS Change water twice a week.
  • PLAY SETS Drill drainage holes in tire swings and in playground equipment where water can collect.
  • PONDS You can grow a lot of mosquitoes in a water garden if you let the water stagnate. Aerate ornamental pools, stock them with mosquito fish (see above), or use mosquito dunks.
  • POOL COVERS Sweep off standing water.
  • POOLS/SPAS Clean and chlorinate even when not in use. A pool left untended by a family on vacation for a month can produce enough mosquitoes to prompt neighborhood-wide complaints.
  • POTTED PLANTS Don’t overwater. Drain saucers weekly with a turkey baster or flush with garden hose.
  • RAIN GUTTERS Keep clear of leaves and other debris.
  • RECYCLING BINS Drill drainage holes in bottom. (If drainage holes are in the sides, enough water can collect in the bottom for mosquitoes to breed in.) Before you put cans in the bin, cut off top and bottom and flatten. Invert glass jars. Crush soft drink bottles and cans. Store newspapers on end, not flat.
  • SCREENS Install and maintain tight-fitting window and door screens.
  • SHRUBBERY Trim and thin shrubs and bushy plants. In the heat of the day, mosquitoes like to hide there.
  • TIRES Properly dispose of old tires – they are the most common mosquito breeding ground in the country. Drill drainage holes in tires used in retaining walls, landscaping, and swing sets.
  • TRAPS In tests, traps that use carbon dioxide (CO2) have been effective at reducing mosquito populations in the immediate area. On the other hand, university studies have repeatedly demonstrated that ultrasonic repellers (that emit high-frequency sound) and bug “zappers” (bugs attracted to a light are electrocuted) do not reduce mosquito numbers.
  • TRASH Get rid of anything that can hold water, including cans, cups, foil, plastic and paper.
  • TRASH CANS AND TRASH BINS Keep tightly covered. Remove water inside and underneath.
  • TREES Eliminate water from dead tree stumps and hollow areas of live trees. Fill cavities with sand or mortar.
  • UMBRELLAS AND BASKETBALL HOOPS If the base for your table umbrella or basketball hoop is filled with water, cap it tightly and seal with duct tape. Or you can fill it with sand instead.
  • WADING POOLS AND WHEELBARROWS Store vertically or turned over.


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