Tick Surveillance, Water Year 2025-2026
Tick Collections from 2025-2026 Season (November 2025 through June 2026)
District laboratory staff completed field collections of nymphal Ixodes pacificus (Western black-legged ticks) in June. Nymphal ticks are collected by flagging with a white sheet of flannel attached to a wooden dowel, in leaf litter areas or on rocks and fallen logs. Ixodes pacificus ticks will be tested for the presence of Borrelia burgdorferi (the agent of Lyme disease), as well as Borrelia miyamotoi (the agent of hard-tick relapsing fever) and Anaplasma phagocytophilum (the agent of granulocytic anaplasmosis).
Parks and other natural areas surveyed in June include Waterdog Lake Park in Belmont, Devil’s Slide Trail and Pedro Point Headlands and San Pedro Valley Park in Pacifica. Seasonal surveillance of ticks is completed for the year, but District staff will continue to respond to residents requesting to have yards or schools inspected for ticks throughout the offseason.
Tick Collections from parks and neighborhoods, 2025-2026 Season (through June 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 | 50 |
| Corte de Madera Creek Open Space Preserve | Portola Valley | 12 | - |
| Mills Canyon Wildlife Refuge | Burlingame | 239 | 5 |
| La Honda Creek Open Space Preserve | La Honda | 254 | 74 |
| Teague Hill Open Space Preserve | Woodside | 224 | 51 |
| Ahni Trail | Pacifica | 13 | - |
| Filoli Estate | Redwood City | 245 | 106 |
| Wavecrest Open Space Preserve | Half Moon Bay | 223 | 55 |
| Año Nuevo State Park | Pescadero | 206 | 50 |
| Pescadero Marsh Natural Preserve | Pescadero | 192 | - |
| Devil's Slide | Pacifica | 225 | 4 |
| Pedro Point Headlands | Pacifica | 144 | 39 |
| Jasper Ridge Biological Preserve | Portola Valley | 394 | 90 |
| Burleigh H. Murray Ranch State Park | Half Moon Bay | 20 | - |
| Edgewood County Park | Redwood City | - | 153 |
| Windy Hill Open Space Preserve | Portola Valley | - | 64 |
| Huddart Park | Woodsdie | 79 | |
| Waterdog Lake | Belmont | 58 | |
| San Pedro Valley Park | Pacifica | 61 |
Page last reviewed: July 1, 2026