Worldwide, nearly 4 million people die each year from various mosquito-borne diseases.  The most common diseases carried by mosquitoes in San Diego County are encephalitis viruses and malaria. By monitoring and reducing mosquito populations, the County of San Diego Vector Control Program protects public health and promotes an environment where residents can enjoy parks, open spaces and other outdoor activities.

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To report mosquito activity or breeding, please call (858) 694-2888 or email us at .


Mosquito Facts

Only female mosquitoes bite. They need the  protein and nutrients from blood for their developing eggs. A mosquito may bite only two or three times during her life, but she can develop hundreds of eggs from each blood meal. There are 24 different types of mosquitoes in San Diego County. At least 7 types are known to carry diseases that can be passed to humans.


The Mosquito Life Cycle


A mosquito has four stages of life:

1. Egg: Once laid in water, eggs will hatch in 2 to 3 days.

2. Larva: A mosquito larva looks like a tiny wiggling worm in the water.

3. Pupa: A larva becomes a pupa and the adult mosquito develops inside.

4. Adult: Total development time from egg to adult can be less than 1 week during periods of warm weather. The average mosquito will live for about 2 weeks.

How to Protect Yourself, Your Family and Community From Mosquitoes

There is no human vaccine to prevent West Nile virus and no specific treatment for the virus. Treatment of severe illnesses includes hospitalization, use of intravenous fluids, respiratory support, prevention of secondary infections, and good nursing care. If you have symptoms of West Nile virus such as fever, rashes, or body aches you should contact your doctor right away.


The best defense against West Nile Virus is to avoid mosquito bites.  You can reduce contact with mosquitoes by taking the following actions:

Mosquitoes spread disease when they bite humans and animals, transferring infected saliva to them. The best way to prevent getting a disease like West Nile virus is to protect yourself from mosquitoes.

  • Wear long sleeves and pants to cover up skin when outdoors
  • Apply an insect repellant that contains DEET, Picadirin, oil of lemon eucalyptus, or IRIR35 to your exposed skin or clothing, follow label instructions
  • Install screens to doors and windows, and keep them well maintained to prevent mosquitoes from entering the home
  • Use larvicide such as, mosquito dunks (Bti) or mosquito fish in backyard ponds, fountains and unused pools to stop larvae from developing into adults. Mosquito dunks are available at most home improvement stores
  • Avoid going outdoors during dawn and dusk hours when mosquitoes are most active
  • Trim and thin shrubs and bushy plants where mosquitoes may hide


The best way to reduce the risk of infection is to avoid mosquito bites. Apply insect repellent that contains either DEET, Picaridin, IR3535, or Oil of Lemon Eucalyptus when you are outdoors. Whenever you use an insecticide or insect repellent, be sure to read and follow the directions carefully.  Avoid applying repellent to children less than 2 years old. Use care in applying repellent on children; repellent on their hands may get into their mouth and eyes, causing irritation.

Remove Breeding Sources

Your help in preventing mosquito breeding is very important. Standing water provides a place for mosquitoes to lay their eggs and mature into biting adults that can spread disease. All mosquitoes need standing water to complete their life cycle.  There are many possible breeding sources around your home. Remove standing water sources like these from around your home:

  • Containers & Buckets: Turn them over or cover them so they do not collect water
  • Swimming Pools/Spas: Keep the water clean and circulating
  • Birdbaths & Troughs: Change the water weekly, or use mosquito fish or larvicide to control breeding
  • Drains & Gutters: Remove dirt and leaves so drains do not clog and collect water
  • Tires: Cover tightly with a tarp. Throw away used tires and drill holes in tire swings to let water drain out
  • Ponds: Use mosquito fish or larvicide to control mosquito breeding
  • Faucets & Hoses: Fix all leaks
  • Potted Plants: Do not over water. Empty saucers weekly or fill them with sand
  • Trash Cans: Clean weekly and keep covered so they do not collect water

Be sure to empty standing water weekly to kill mosquito larvae.


Mosquito Fish

Mosquito fish are an effective and natural methods of controlling mosquitoes. They are small, freshwater fish (1-2 inches long) that eat mosquito larvae.  Mosquito fish are ideal for controlling mosquito larvae in backyard ponds, birdbaths, fountains, animal troughs, unused swimming pools and other standing water sources.

Mosquito fish should never be placed in any natural habitat such as lakes, streams, rivers or creeks. They are greedy eaters, so by placing them into natural waterways, they may impact natural species and disrupt the balance of life.

Mosquito fish may be picked up free of charge at different locations throughout San Diego County. 

Learn more about mosquito fish and their care

Find the closest mosquito fish location

Contact the San Diego County Vector Control Program if:

  • You have tried to control for mosquitoes and you are still having problems
  • Mosquitoes are coming from a local lagoon, stream, riverbed or other large water source
For More Information On 
Mosquitoes  Or Other Vectors Contact: 
(858) 694-2888
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