Mosquito Control


Mosquito Control

Why Control Mosquitoes?

Mosquitoes are more than a nuisance! They can carry and transmit diseases that can make people very sick. Even when they don’t transmit disease, their bites may be uncomfortable or become infected.

Controlling mosquitoes interrupts the disease transmission cycle and protects people from disease.

How We Control Mosquitoes

The District controls mosquitoes through a program of integrated mosquito management (IMM). This program focuses on controlling mosquitoes in their larval stage and preventing problems before they occur.

Larval control has many benefits:

  • Lower toxicity. The pesticides used to control the larval stage are much less toxic to the environment and are highly specific to mosquitoes.
  • Less pesticides. The pesticides are applied to a smaller area than would be required for treatment of adult mosquitoes.
  • Less disease. Targeting immature mosquitoes kills them before they are capable of transmitting disease.

Sometimes, however, it is also necessary to control adult mosquitoes, such as when we find that they are carrying a disease that can be transmitted to humans.

A uniformed technician leans from a truck to spray into a street grate.


Underground Sources

Water that collects underneath buildings, in storm drains, vaults and other underground sites in San Mateo County are very significant sources of mosquito development. These sources are the preferred habitat of the northern house mosquito (Culex pipiens), which is an efficient vector of West Nile virus. Adults of Culex pipiens are most abundant during the summer.

Mosquito Fish

Mosquito Fish

The District will deliver fish, at no additional cost, to county residents for control of mosquitoes in backyard ponds. The water in the pond must first be treated to remove chloramine (a sterilizing agent that is present in tap water). Products to remove chloramine can be purchased at a local pet store or aquarium specialist.

What is a mosquito fish?


Adult Mosquito Control

San Mateo County Mosquito and Vector Control District takes a preventative approach to mosquito control. Whenever possible, mosquitoes are controlled in their immature stages, before they emerge as biting adults capable of transmitting disease to humans.

Sometimes, however, adult mosquito populations become a threat to human health. When this happens, information collected through mosquito surveillance is used to make the decision to reduce adult mosquito populations.