San Mateo County Mosquito & Vector Control District

10/23/2026

Termites are out!

We're getting calls and questions from lots of residents about termites. Learn more about termites here:

Autumn is the time of year for termite swarms. Adult winged termites (called alates) leave their colonies to mate and establish new colonies.

10/23/2026

West Nile virus detected in a dead crow from East Palo Alto

West Nile virus was recently detected in a dead American crow collected from East Palo Alto. West Nile virus is spread to people, birds, and horses through the bite of an infected mosquito.

It only takes a small amount of water to produce mosquitoes, so following these simple steps can reduce the risk of mosquitoes and the diseases they transmit:

- Dump standing water at least once a week, including in flowerpots and saucers, old tires, buckets, pet dishes, and trash cans. Mosquitoes can lay their eggs in very small amounts of standing water.

- When outside and mosquitoes are active, apply insect repellent containing an active ingredient registered with the Environmental Protection Agency – such as DEET, picaridin, oil of lemon eucalyptus, or IR3535 – according to label instructions.

- Wear long sleeves and pants, especially if outside at dawn and dusk when mosquitoes are most active.

- Install screens on windows and doors, and keep them in good repair to keep mosquitoes out of your home.

- Clean rain gutters clogged with leaves.

- Report dead birds to the statewide West Nile Virus Call Center by phone at 1-877-WNV-BIRD (1-877-968-2473) or online (https://westnile.ca.gov/). Not all birds can be collected for testing, but all reports help the District identify potential risk areas for West Nile virus.

- Report biting mosquitoes - call us at 650­­-344-8592 or submit a request for service online at https://www.smcmvcd.org/

For more information about West Nile virus and District services, go to the District’s website at https://www.smcmvcd.org/

10/15/2026

Tratamiento contra zancudos programado para partes de Redwood City y North Fair Oaks - domingo 18 de octubre entre 4am y 6am

Visite www.smcmvcd.org/adult-mosquito-control-updates para ver un mapa de las áreas específicas de tratamiento y más información.

No es necesario permanecer en el interior ni cerrar puertas y ventanas durante el tratamiento. Al aplicarse con aspersora de volumen ultra baja, las gotitas permanecen en el aire no más de 30 minutos.

Los residentes que tengan estanques con peces o colmenas de abejas deben cubrirlos durante el tratamiento.

Visite www.smcmvcd.org/join-our-mailing-list para suscribirse a las notificaciones por correo electrónico del Distrito.

10/15/2026

Mosquito control treatment scheduled for parts of Redwood City and North Fair Oaks - Sunday, October 18 between 4am and 6am

Visit www.smcmvcd.org/adult-mosquito-control-updates to see a map of the specific treatment areas and additional information.

It is not necessary to stay inside or close doors and windows during the treatment. When applied as an ultra-low volume spray, the droplets remain in the air no longer than 30 minutes.

Residents with fishponds or bee hives should cover them during the treatment.

Visit www.smcmvcd.org/join-our-mailing-list to sign up for email notifications from the District.

10/14/2026

Invasive Aedes aegypti mosquito found in White Oaks neighborhood of San Carlos

We are checking properties in the area to determine how widespread the Aedes aegypti mosquitoes are in the area.

Aedes aegypti are small (about ¼ inch) black and white mosquitoes that bite aggressively during the day. They are an invasive species not native to California, but they have become established throughout the United States, including in many California counties. Aedes aegypti mosquitoes can potentially spread several diseases, including dengue, chikungunya, Zika, and yellow fever. At this time, the risk of Aedes aegypti spreading disease in San Mateo County is very low.

“We will be relying on residents’ cooperation in the White Oaks neighborhood as we work to determine how widespread this invasive mosquito is in San Carlos. Please work with our staff to allow property access as swiftly as possible,” said Operations Director Casey Stevenson.

Read the full press release at: https://www.smcmvcd.org/invasive-aedes-aegypti-mosquitoes-found-in-san-carlos

09/10/2026

Invasive Aedes aegypti mosquito found in North Fair Oaks

The San Mateo County Mosquito and Vector Control District has recently detected invasive Aedes aegypti mosquitoes in North Fair Oaks. The District is checking properties in the area to determine how widespread the Aedes aegypti mosquitoes are in the area.

Aedes aegypti are small (about ¼ inch) black and white mosquitoes that bite aggressively during the day. They are an invasive species not native to California, but they have become established throughout the United States, including in many California counties. Aedes aegypti mosquitoes can potentially spread several diseases, including dengue, chikungunya, Zika, and yellow fever. At this time, the risk of Aedes aegypti spreading disease in San Mateo County is very low.

“Our staff need only a few minutes to check around the yard for water where mosquitoes can grow. Neighbors who welcome us to visit their properties help us be as efficient as possible. Our goal is to keep these dangerous mosquitoes from spreading throughout the area,” said Operations Director Casey Stevenson.

Read the full press release at: https://www.smcmvcd.org/invasive-aedes-aegypti-mosquito-found-in-north-fair-oaks

09/10/2026

Se detecta el zancudo invasor Aedes aegypti en North Fair Oaks

El Distrito de Control de Mosquitos y Vectores del Condado de San Mateo ha detectado zancudos Aedes aegypti en North Fair Oaks. El Distrito está inspeccionando propiedades en la zona para determinar qué tan extendida está la presencia de zancudos Aedes aegypti en la área.

Los Aedes aegypti son zancudos pequeños (de aproximadamente 6 mm), de color blanco y negro, que pican agresivamente durante el día. Son una especie invasora que no es originaria de California, pero se han establecido en varias partes de Estados Unidos, incluyendo muchos condados de California. Los zancudos Aedes aegypti pueden transmitir varias enfermedades, como el dengue, la chikungunya, el Zika y la fiebre amarilla. Actualmente, el riesgo de que el Aedes aegypti propague enfermedades en el condado de San Mateo es muy bajo.

“Nuestro personal solo necesita unos minutos para revisar el jardín en busca de agua donde puedan crecer los zancudos. Los vecinos que nos permiten visitar sus propiedades nos ayudan a ser lo más eficientes posible. Nuestro objetivo es evitar que estos zancudos peligrosos se propaguen por toda la zona”, declaró el Director de Operaciones, Casey Stevenson.

Lea el comunicado de prensa completo aquí: https://www.smcmvcd.org/invasive-aedes-aegypti-mosquito-found-in-north-fair-oaks

07/29/2026

A dead crow found in Menlo Park tested positive for West Nile virus.

What can you do?
- Report dead birds (https://westnile.ca.gov/report)
- Use an EPA-insect repellent (https://www.smcmvcd.org/epa-registered-insect-repellent)
- Dump standing water at least once a week to prevent mosquitoes
- Report biting mosquitoes (https://www.smcmvcd.org/report-biting-mosquitoes)

07/27/2026

Se detecta el zancudo invasor Aedes aegypti en Redwood City

El Distrito de Control de Mosquitos y Vectores del Condado de San Mateo ha detectado zancudos Aedes aegypti recientemente en el vecindario de Friendly Acres de Redwood City. El Distrito está inspeccionando propiedades en la zona para determinar qué tan extendida está la presencia de zancudos Aedes aegypti en la área.

Los Aedes aegypti son zancudos pequeños (de aproximadamente 6 mm), de color blanco y negro, que pican agresivamente durante el día. Son una especie invasora que no es originaria de California, pero se han establecido en varias partes de Estados Unidos, incluyendo muchos condados de California. Los zancudos Aedes aegypti pueden transmitir varias enfermedades, como el dengue, la chikungunya, el Zika y la fiebre amarilla. Actualmente, el riesgo de que el Aedes aegypti propague enfermedades en el condado de San Mateo es muy bajo.

“Necesitamos la ayuda de la comunidad para detener este zancudo. Nuestro personal está trabajando arduamente para prevenir la propagación de este zancudo. Nuestro objetivo es controlar y eliminar los zancudos Aedes aegypti invasores del condado de San Mateo,” declaró el Gerente del Distrito Brian Weber.

Lea el comunicado de prensa completo aquí: https://www.smcmvcd.org/se-detecta-el-zancudo-invasor-aedes-aegypti-en-redwood-city

07/27/2026

Invasive Aedes aegypti mosquito found in Redwood City

The San Mateo County Mosquito and Vector Control District has recently detected invasive Aedes aegypti mosquitoes in the Friendly Acres neighborhood of Redwood City. The District is checking properties in the area to determine how widespread the Aedes aegypti mosquitoes are in the area.

Aedes aegypti are small (about ¼ inch) black and white mosquitoes that bite aggressively during the day. They are an invasive species not native to California, but they have become established throughout the United States, including in many California counties. Aedes aegypti mosquitoes can potentially spread several diseases, including dengue, chikungunya, Zika, and yellow fever. At this time, the risk of Aedes aegypti spreading disease in San Mateo County is very low.

“We need the public’s help to stop this mosquito. Our staff are working hard to prevent the mosquito from spreading. Our goal is to control and eliminate invasive Aedes aegypti mosquitoes from San Mateo County,” said District Manager Brian Weber.

Read the full press release at: https://www.smcmvcd.org/invasive-aedes-aegypti-mosquito-found-in-redwood-city