Tick Surveillance, Water Year 2025-2026
Tick Collections from 2025-2026 Season (November 2025 through May 2026)
District laboratory staff continued winter surveillance for adult Ixodes pacificus (Western black-legged ticks) in January. Ticks are collected by dragging a one-meter square sheet of white flannel over the vegetation alongside trails; a technique called “flagging.” Ixodes pacificus ticks are brought back to the District and tested for pathogens. Collections will continue through the spring.
This January, staff continued tick inspections of residential properties as part of an ongoing project to evaluate the risk of tick exposure in yards. This season, staff are focusing primarily on the San Mateo Highlands and Hillsborough Heights neighborhoods.
Regular seasonal tick surveillance was also conducted in Mills Canyon in Burlingame, Wunderlich County Park in Woodside, Teague Hill Open Space Preserve in Woodside, Filoli Estate near Redwood City, Ahni Trail in Pacifica, Wavecrest Open Space Preserve in Half Moon Bay, Año Nuevo State Park in Pescadero, La Honda Creek Open Space Preserve in La Honda and Pescadero Marsh Natural Preserve in Pescadero.
Tick Collections from parks and neighborhoods, 2025-2026 Season (through January 2025)
| Park/Neighborhood | Nearest City/Town | Number of Ix. pacificus adults |
|---|---|---|
| Coal Creek Open Space Preserve | Portola Valley | 437 |
| Wunderlich Park | Woodside | 265 |
| Laurelwood Park | San Mateo | 320 |
| Corte de Madera Creek Open Space Preserve | Portola Valley | 12 |
| Mills Canyon Wildlife Refuge | Burlingame | 239 |
| La Honda Creek Open Space Preserve | La Honda | 105 |
| Teague Hill Open Space Preserve | Woodside | 169 |
| Ahni Trail | Pacifica | 13 |
| Filoli Estate | Redwood City | 245 |
| Wavecrest Open Space Preserve | Half Moon Bay | 111 |
| Año Nuevo State Park | Pescadero | 182 |
| Pescadero Marsh Natural Preserve | Pescadero | 107 |
Page last reviewed: February 6, 2026