Mosquitoes are more than just a nuisance. Not only can their bites cause severe allergic reactions, but they can also spread debilitating diseases that can sometimes be fatal. In fact, mosquitoes are responsible for more than one million deaths per year worldwide.

The Marin/Sonoma Mosquito and Vector Control District is dedicated to protecting public health by monitoring, treating, and managing more than 20,000 sources of mosquito production throughout Marin and Sonoma counties. This is accomplished using an Integrated Vector Management (IVM) program. A vector is any animal that can transmit disease or cause harm to people or animals. The District’s IVM program consists of five different tools (Education, Surveillance, Physical Control/Source Reduction, Microbial and Chemical Control, and Biological Control) that work together and support each other.

Education

Education is the cornerstone of the District’s IVM program. The community outreach department works year-round to educate the public about the role the District plays in protecting public health, and informs them how they can reduce vector populations around their home. The District takes a multifaceted approach to community outreach, using a variety of methods such as traditional and online media campaigns, social media, and participation in local events.

Surveillance

The District closely monitors the numbers and types of mosquitoes in an area and tests for viruses using specialized trapping and testing methods. This information helps staff efficiently control vectors and vector-borne diseases in Marin and Sonoma counties.

Physical Control/Source Reduction

Physical control, or source reduction, modifies an environment to reduce mosquito populations. This may minimize, and in some instances eliminate, the need to use mosquito larvicides and/or adulticides. Examples of source reduction include emptying containers, filling in potholes, promoting effective drainage, controlling vegetation, and timing irrigation appropriately. The District also employs physical control measures on a much larger scale, often in collaboration with other agencies. Large-scale projects, such as improving tidal circulation in salt marshes, help minimize mosquito production while improving habitat conditions for other plants and animals, including endangered species.

Microbial and Chemical Control

The District’s field surveillance work helps determine whether mosquito control applications with larvicides or adulticides are necessary. Larvicides, often based on naturally occurring materials, are applied directly to water to control mosquito larvae. Larvicides are often used with other mosquito control measures in an IVM program to minimize the number of adult mosquitoes that fly off a source. This not only reduces the potential for mosquito-borne diseases, but also minimizes, and sometimes eliminates, the need to control adult mosquitoes. Adult mosquito control is conducted when necessary to reduce populations, or when emergency control measures are needed to rapidly disrupt the potential transmission of disease to humans.

Biological Control

Biological control uses a living organism to control a particular vector or pest. One of the biological control tools the District uses are mosquitofish, Gambusia affinis, which are native to the southern and eastern parts of the United States. They were introduced into California in the early 1920s for the control of mosquito larvae and continue to be an important component of the District’s IVM program. Their voracious appetite for mosquito larvae and pupae makes these fish an excellent control option for use in backyard ponds and other artificial water sources.

The Marin/Sonoma Mosquito and Vector Control District's programs and services are funded through property taxes and benefit assessments, and are provided to all residents in Marin and Sonoma counties at no additional charge. 

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