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 March. 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.
Adult seasonal tick surveillance was conducted at Jasper Ridge Biological Preserve in Woodside and Burleigh H. Murray Ranch State Park in Half Moon Bay,
Tick collection in spring shifts to focus on the nymphal stage, because it is the season when nymphs are most active. Surveys for nymphs have been conducted this season at Pedro Point Headlands in Pacifica, Edgewood Park in Redwood City, Wunderlich Park in Woodside, Windy Hill Open Space Preserve in Portola Valley, and Wavecrest Open Space in Half Moon Bay.
Tick Collections from parks and neighborhoods, 2025-2026 Season (through March 2026)
| Park/Neighborhood | Nearest City/Town | Number of Ix. pacificus adults | Number of Ix. pacificus nymphs |
|---|---|---|---|
| Coal Creek Open Space Preserve | Portola Valley | 437 | - |
| Wunderlich Park | Woodside | 265 | 87 |
| 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 | 31 |
| Wavecrest Open Space Preserve | Half Moon Bay | 223 | 44 |
| Año Nuevo State Park | Pescadero | 206 | - |
| Pescadero Marsh Natural Preserve | Pescadero | 192 | - |
| Devil's Slide | Pacifica | 224 | - |
| Pedro Point Headlands | Pacifica | 141 | 17 |
| Jasper Ridge Biological Preserve | Portola Valley | 123 | - |
| Burleigh H. Murray Ranch State Park | Half Moon Bay | 20 | - |
| Edgewood County Park | Redwood City | - | 96 |
| Windy Hill Open Space Preserve | Portola Valley | - | 28 |
Page last reviewed: April 2, 2026