Mosquito Prevention Tips


Dump and drain standing water around your house weekly since it's where mosquitoes lay eggs, including: tires, cans, flowerpots, clogged rain gutters, rain barrels, toys, puddles and even unused fountains. In addition, tip and toss unnecessary outdoor containers.

Dusk & Dawn
Dusk and dawn are when mosquitoes that carry the virus are most active, so limit outdoor activities or take extra care to use repellents and protective clothing during evening and early morning hours.  Be sure to use tight fitting screen on windows and doors to prevent mosquitoes from entering your home.

DEET & Repellents
Apply EPA registered insect repellent containing one of the following active ingredients: DEET, Picaridin, IR3535, Oil of Lemon Eucalyptus (OLE) or Para-menthane-diol (PMD) when outdoors, according to label instructions.

Dress in long sleeves and pants and other protective clothing when outside during dawn and dusk or in areas where mosquitoes are active. Mosquitoes may bite through thin clothing, so when practical,  double layers of clothing may add better protection.

Call San Joaquin County Mosquito and Vector Control District to report significant mosquito infestations and daytime biting mosquitoes at (209) 982-4675.


Standing water locations around the home.

Simple tasks, done on a regular basis, will help protect and prevent mosquito development on your property.

Did you know that many mosquitoes lay "egg rafts" and that each one can contain between 100 to 400 eggs?
Recently an invasive mosquito, commonly called the Yellow Fever mosquito or Aedes aegypti, was discovered in San Joaquin County. It glues individual eggs on the sides of yard containers and they won’t hatch for several years until water levels reach them.  It only takes mosquitoes several days to go from egg to adult mosquito. Therefore, here are some easy steps to help control mosquitoes around the home.

Every week, dump and scrub containers that hold standing water. Keep rain gutters free of debris; keep decorative fountains operational or drain the water; and change water in animal watering dishes and bird baths often.  Remove and dispose of all unused containers that will collect rain or water from sprinklers. These items include, but are not limited to, cans, jars, barrels, old tires, buckets, flower pots and saucers, toys, bottle caps.

3. Rain Barrels

Photo of rain barrel less likely to provide areas for mosquito development

Rain barrels increase in popularity during drought seasons. Using a rain barrel to capture runoff is a great way to conserve water for your yard and plants. However, homemade and some commercially produced  rain barrels often become a significant source of mosquito development.

Rain Barrels are storage containers that collect rain water from downspouts. Normally, downspouts lead the rain water from the roof to the ground or storm sewer. The rain barrel is connected into the downspout system where water is diverted, in order to capture and store some of the rain water. Rain barrels are normally comprised of a plastic storage container with a system that diverts water into the barrel usually consisting of a small gauge tight fitting screened opening on top, an overflow valve, and a spigot to which a hose can attach. It is important that the top be flat so no water accumulates.

Follow these tips to avoid mosquitoes developing in your rain barrel system:

  1. Only use barrels specifically designed for rainwater collection.
  2. Place barrels so excess water drains.
  3. Flat barrel lids leave no area for water collection.
  4. Overflow valves prevent water from collecting on lids and drains excess water.
  5. Use tight fitting, fine mesh (1/16 gauge) screen on all barrel openings (including the overflow valve).
  6. A spigot valve placed at the very base of the barrel helps to empty the barrel completely.
  7. Use the collected water first before any other water sources and drain the barrel completely.
  8. Completely empty rain barrels and clean weekly to prevent stagnant water.

Call the San Joaquin County Mosquito & Vector Control District for additional help or if mosquito development is present (209) 982-4675.

4. Additional tips for outdoor mosquito prevention

Ornamental Ponds

A beautiful ornamental pond with fish

Stock with mosquitofish. Add goldfish for looks, if desired. Avoid spraying with garden insect sprays. Remove leaves and thin out pond lilies. Keep the water level up. Screen the inlet of recirculation pumps to prevent fish from being pulled through the system. Chlorine kills fish-- transfer fish to glass bowl when cleaning pond. If pond is no longer desired, break holes in bottom and fill with dirt or sand.  See our “About Mosquitofish” publication for more details.

Concrete or Plastic Swimming Pools

Run pool pumps daily to operate the filter and skimmer,  removing mosquito egg rafts and larvae. Chlorine will NOT kill mosquito larvae. If a pool cover is used, keep it tightly sealed. Remove rainwater from top of pool cover. Stock unused or "out-of-order" pools with mosquitofish. Report neglected neighborhood pools anonymously to the District. Call the District at (209) 982-4675

Boats, Kayaks & Canoes

An old tire leaning against a wooden fence

Prevent accumulation of bilge water and rain water. Store small boats, kayaks and canoes upside down or cover to keep out the rain and water from sprinklers.

Other kinds of Containers

Tires without center wheels hold rain and sprinkler water. Store these tires in a shed or barn. Better yet, properly dispose of used tires at your local solid waste facility.

Home gardeners rooting plant cuttings in vases, buckets, etc. should change water every week. Usable containers should be stored upside down.


Photo of immature mosquitoes in larvae form
Immature mosquitoes in the larvae form,
breathing at the surface of the water.

Report Dead Birds to California Department of Public Health at or 1-877-968-2473.
Dead birds may be an indicator that West Nile virus is circulating between birds and the mosquitoes in an area. Over 225 species of birds are known to have been infected with West Nile virus, though not all infected birds will die. It's important to remember that birds die from many other causes besides West Nile virus.

By reporting dead birds to toll free hotline 1-877-968-2473, you can play an important role in monitoring West Nile virus. For additional information about reporting dead birds online, follow this link; Report Dead Birds.

Report Neglected Swimming Pools to Your Local Mosquito Control District

Dirty, neglected swimming pools are a breeding ground for mosquitoes and pose a public health hazard for mosquito-borne disease. Please report neglected neighborhood pools anonymously to the District.  Please note that our technicians will treat the pool to stop mosquito development. The District doesn’t require the pool to be cleaned or repaired. We will continue to monitor the pool for mosquito development. 

Additional Questions on Mosquito Control:

Call San Joaquin County Mosquito and Vector Control District at (209) 982-4675.  Please follow us on our Facebook page at SJmosquitoandvector.

To find your county’s local mosquito control agency click here. The Mosquito and Vector Control Association of California (MVCAC) holds a wealth of knowledge on control and surveillance in California. More questions about mosquito control? View the “Best Management Practices for Mosquito Control in CA” by California Department of Public Health, A source for information about pesticides and repellents is the National Pesticide Information Center, which also operates a toll-free information line: 1-800-858-7378 (check their website for hours).

West Nile Virus and
Dead Bird Hotline

(877) 968-BIRD (2473)

or online at

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