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 February. 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.
Regular seasonal tick surveillance was conducted at Devil’s Slide in Pacifica, Pedro Point Headlands in Pacifica, Teague Hill Open Space Preserve in Woodside, La Honda Creek Open Space Preserve in La Honda, Año Nuevo State Park near Pescadero, Wavecrest Open Space Preserve in Half Moon Bay, and Pescadero Marsh Natural Preserve in Pescadero. Additionally, District staff surveyed for ticks at a school in Hillsborough.
Tick Collections from parks and neighborhoods, 2025-2026 Season (through February 2026)
| 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 | 254 |
| Teague Hill Open Space Preserve | Woodside | 210 |
| Ahni Trail | Pacifica | 13 |
| Filoli Estate | Redwood City | 245 |
| Wavecrest Open Space Preserve | Half Moon Bay | 223 |
| Año Nuevo State Park | Pescadero | 206 |
| Pescadero Marsh Natural Preserve | Pescadero | 192 |
| Devil's Slide | Pacifica | 224 |
| Pedro Point Headlands | Pacifica | 141 |
Page last reviewed: March 17, 2026