August 2026 Newsletter

Invasive Aedes aegypti mosquitoes found in Redwood City

Mosquito on a white background. The mosquito has an abdomen full of dark red blood. The mosquito is mainly black, with some white stripes on its legs.
Invasive Aedes aegypti mosquitoes are small, black-and-white mosquitoes that bite during the day.

We've been keeping an eye out for invasive Aedes aegypti mosquitoes since last eradicating them from the County in 2015.

In late July, a call from a resident about "very aggressive mosquitoes with white-striped legs" led us to find these daytime-biting mosquitoes in the Friendly Acres neighborhood of Redwood City. (Click here to read the press release)

What are we doing?

A person is tending to potted flowers in a garden, focusing on plant care.
Checking for small amount of hidden water is critical for getting rid of Aedes aegypti. Here Vanessa checks for water in plant saucers.
  • We are doing door-to-door visits of all properties in the area to determine how widely spread the Aedes aegypti mosquitoes are.  To-date, we've visited nearly 250 properties. We are grateful for the continued cooperation of many helpful residents who allowed us access to check their properties. Residents providing access to their properties has played an important part in our ability to determine whether these mosquitoes have spread beyond the initial detection area.
  • We've been setting extra traps in the immediate area and nearby areas to determine how widespread the issue is.
  • We've been working to spread the word about the importance of reporting biting mosquitoes and dumping standing water (see below for how you can help!).
  • As of early August, there have been no additional detections of any invasive Aedes aegypti in any water sources or traps.

What can you do?

  • Dump standing water at least once every week. Invasive Aedes aegypti mosquitoes need only a very small amount of water - only a bottle cap size(!) - to lay their eggs. So be sure to check for and dump out any standing water at least once every week around your home.
  • Learn a little about mosquitoes. (Not a lot! We know you're busy!)
    • Mosquitoes need water to grow from eggs to flying adults.  Female mosquitoes lay eggs on or very near water. When the eggs are wet, small larvae hatch out (see larvae in this short video from our friends at San Gabriel Valley Mosquito & Vector Control District). They eventually develop into pupae (also in the water) before growing into airborne, flying adults.
    • There are about 20 different kinds of mosquitoes in San Mateo County. Only certain mosquitoes can spread diseases. Our staff are experts at identifying mosquitoes, so call us for help!
    • Know that only female mosquitoes bite. Mosquito control efforts in some other areas (including just across the Bay in Alameda County) release sterile male mosquitoes to help control invasive mosquito populations. We're not currently using this method, but we can answer any questions you might have - give us a call!
  • Report biting mosquitoes to us at 650-344-8592 or by requesting service online.
  • Sign-up for alerts. We have a few different email lists.  If you got this email directly from us, you are on our 'newsletter' distribution list.  If you would also like to receive email notifications about our press releases and/or scheduled mosquito control treatments, you can sign up here.
  • Tell friends and neighbors about us! Mosquito prevention is a community-wide effort. Tell your neighbors about the importance of dumping standing water every week, and let them know they should call us if they are getting mosquito bites. Please help spread the word - it can be as easy as forwarding this newsletter!
  • Stay up-to-date on our work related to invasive Aedes aegypti mosquitoes by checking this page, where we'll post updates.

 

West Nile virus activity

We have detected West Nile virus in several dead birds in the Menlo Park/Atherton area. To stay up-to-date with West Nile virus information, visit this page.

 

The image features a man examining a specimen in a bag, with "Annual Report 2025" for the San Mateo County Vector Control District.

2025 Annual Report

We are pleased to share our 2025 Annual Report. The report contains information about our board, finances, services, and metrics from 2025. Check it out and let us know any questions!

 

Open House - success!

A lively gathering in a room with people engaging in activities, exploring exhibits, and interacting at various tables.

Our Open House was held on June 27. We had a great time showing attendees what we do! We hope to see you next year! Sign-up here to receive updates about next year's Open House.

A lively gathering in a room with people engaging in activities, exploring exhibits, and interacting at various tables.
The lab was busy with visitors!
A person teaches a child about insects at a lab counter, with displays and a microscope in a science learning environment.
Vector Ecologist Arielle and a very young visitor using a digital magnifier.
A woman examines specimens at a table, surrounded by people engaged in a science or educational event.
Visitors enjoyed some hands-on displays in the lab.
People are gathered outdoors, near a drone and equipment, with cones marking off areas, under a clear blue sky.
Drone pilot Sean explains details to visitors.
A man engages with two women at a booth showcasing information on larvicides and pest control products.
Vector Control Technician Evan shares information with visitors.
A group of people are gathered around a hovercraft setup under sunny skies, with tents and trailers in view.
Operations Director Casey share information about the airboat with visitors.
A lively gathering in a room with people engaging in activities, exploring exhibits, and interacting at various tables.
A person teaches a child about insects at a lab counter, with displays and a microscope in a science learning environment.
A woman examines specimens at a table, surrounded by people engaged in a science or educational event.
People are gathered outdoors, near a drone and equipment, with cones marking off areas, under a clear blue sky.
A man engages with two women at a booth showcasing information on larvicides and pest control products.
A group of people are gathered around a hovercraft setup under sunny skies, with tents and trailers in view.

 

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