In this month's District Report: honoring trustee James Ridgeway, seasonal mosquitoes, and more.
View this email in your browser

District News

  • One bird tested positive for West Nile virus in November. No samples positive for West Nile virus were collected in December. The year-end total for the 2015 West Nile virus season can be found on the District website.
  • Tick collection has begun for the 2015-2016 winter season. Weather permitting, District staff will collect and test Ixodes pacificus ticks from fifteen parks throughout the county. See below for the list of parks planned for surveillance this season.
  • On October 16, Laboratory Director Nayer Zahiri gave a presentation to San Mateo County school nurses about head lice.  The talk included information on how to inspect for lice and recommendations for managing head lice in a classroom, which the nurses can share with teachers and parents.
  • Trustee Field Day was held at the District on December 9th.  Trustees had the opportunity to meet with the technician working in their city and learn about local mosquito and vector control activities.
  • All staff attended training for the new MapVision database at the District in mid-December. This new database includes map-based software that provides visual displays of vectors and pesticide applications in the field, immediate incorporation of data, and faster response time for service calls.  The District plans to implement the new database at the beginning of February.
The District asks residents to report dead birds or tree squirrels by calling (650) 344-8592 or online at Specimens that appear to have been dead for less than 24 hours and are in good condition will be tested for West Nile virus.

Honoring Trustee James Ridgeway

In October, the Board of Trustees passed a resolution thanking trustee James Ridgeway for his service to the District. Dr. Ridgeway was first appointed to the Board in 2007, and generously gave his time for more than eight years. During his time as trustee for the City of San Mateo, he served as a member of the Finance, Legislative, Environmental, and Strategic Planning Committees, and served as Chair of the Strategic Planning Committee from 2013-2015.

Dr. Ridgeway passed away on December 16th, 2016. His wisdom and kindness will be missed by the Board and staff, as well as the community as a whole.

Facility Maintenance Technician Paul Weber, then a seasonal staff member, collects ticks for disease testing at a local park.

Tick Collection Season Begins

During the winter season, District staff collect Ixodes pacificus (Western-blacklegged ticks) from parks in San Mateo County. This year, ticks will be collected from the following parks:
  • Frontierland Park – Pacifica 
  • Memorial County Park – Loma Mar 
  • San Bruno Mountain – San Bruno 
  • Eaton Park – San Carlos 
  • Big Canyon Park – San Carlos 
  • Waterdog Lake – Belmont 
  • Huddart County Park - Woodside 
  • Thornwood Open Space Preserve – near Woodside 
  • Pulgas Ridge Open Space Preserve – Redwood City 
  • Junipero Serra County Park – San Bruno 
  • Quarry Park – El Granada
  • Los Trancos Open Space Preserve – near Portola Valley 
  • Edgewood County Park – Redwood City 
  • San Pedro Valley County Park – Pacifica 
  • Crystal Springs Regional Trail County Park – San Bruno to Woodside
Parks are chosen based on tick population levels from previous years, abundance of tick habitat, and community usage; tick collection at a park does not necessarily indicate an elevated risk of tick-borne disease.

The ticks collected at these parks will be tested for the presence of three disease causing bacteria: Borrelia burgdorferiBorrelia miyamotoi, and Anaplasmosis. Results will be available on the District website at the end of the tick collection season.

Community members interested in the tick collection process are invited to join the District on February 6th (weather permitting) to collect ticks for disease surveillance at San Bruno Mountain. For more information, visit

A Mosquito for Every Season

Vector ecologists sort and identify mosquitoes collected by the District's mosquito surveillance program.

You might think of mosquitoes as a summer problem, but here in San Mateo County, vector control technicians fight a year-round battle with an ever-changing array of mosquito species.

In the spring, when rain is common, the District fights Aedes squamiger, the California salt marsh mosquito.  Aedes squamiger will fly up to twenty miles in search of a blood meal, preferably from a human or other mammal, making it a serious nuisance in many areas of the county. Aedes washinoi, the freshwater mosquito, is also common in spring, but causes fewer problems because it rarely flies more than a half mile from its water source. Another concerning spring mosquito is Aedes sierrensis, the western treehole mosquito. As its name suggests, it breeds in woodsy areas where rainwater accumulates in treeholes.  In addition to feeding aggressively on humans, the western treehole mosquito is an important vector of dog heartworm.

As spring turns into summer, mosquito problems intensify. San Mateo County has five species of Anopheles mosquitoes capable of transmitting malaria. While malaria has been eradicated in California for many years, it is important to control Anopheles mosquitoes to avoid reintroduction of malaria via infected travelers returning from other areas.

Throughout the summer, the District also fights another mosquito-borne disease, West Nile virus, by controlling Culex mosquito populations. Culex pipiens, the northern house mosquito, can be found year-round, but
most Culex pipiens complaints from residents occur during the warm summer months.  In addition to being a persistent indoor biting nuisance, this mosquito is the most important vector species for West Nile Virus in urbanized areas.  For this reason, control of Culex pipiens is also a primary objective of the summer catch basin treatment program. Other Culex mosquitoes common during the summer include Culex tarsalis, the western encephalitis mosquito, and Culex erythrothorax, the tule mosquito. Both species can transmit West Nile virus and other diseases, but are not the primary vector of the disease in San Mateo County.

For more information on San Mateo County's mosquito species and their control, visit the District website at

Mosquito Surveillance and Control Data Updates

Visit our Mosquito Surveillance Data and Operations Statistics pages to get the latest data from our mosquito surveillance and control program. 

Our Work by the Numbers

In December, District staff:

District Financial Information for October and November, 2015

Visit our Financial Information page for the latest District financial information, including the Consolidated Funds and Profit and Loss as of November 30th, 2015. 

Snapshots from the Field

Technician Stephanie Busam uses an amphibious vehicle to treat areas of saltwater marsh.
Technician Kim Keyser displays a tussock moth caterpillar, a species frequently seen in winter.
A breached levee at Bair Island now allows natural tidal flow, eliminating mosquito breeding and creating habitat for native wildlife.
Assistant manager Brian Weber documents water levels during a recent king tide.
San Mateo County Mosquito and Vector Control District
Protecting public health since 1916

1351 Rollins Rd. | Burlingame CA 94041
(650) 344—8592 |