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Common Ticks of San Mateo County

Although there are 21 species of hard ticks in San Mateo County, the list below are the most common ticks that people and pets contact in the environment.

Ticks Characteristics
Ixodes pacificus
Ixodes pacificus
“Western Black-Legged Tick”
  • Adults quest along trails November to May
  • Adults feed readily on humans, horses, dogs, and other large mammals
  • Larvae and nymphs are active March to early August, peaking in April to June
  • Larvae and nymphs feed primarily on lizards but may also attach to rodents and people
  • Importance: Primary vector of Lyme disease to humans in California
Dermacentor occidentalis
Dermacentor occidentalis
“Pacific Coast Tick”
  • Adults feed on cattle, horses, deer, dogs, and humans
  • Adults reach peak activity from April through May but are present along trails from November through August
  • Larvae and nymphs feed on small rodents and other small mammals in spring and summer
  • Vector of Tularemia and Rocky Mountain Spotted Fever, and both have been detected in ticks in San Mateo County
Dermacentor variablis
Dermacentor variablis
“American Dog Tick”
  • Adults feed on dogs and large mammals, including humans
  • Adults along trails primarily from March through July
  • Larvae and nymphs feed on rodents and other small mammals, they are active from late winter to summer
  • Vector of Tularemia and Rocky Mountain Spotted Fever, and both have been detected in this tick in San Mateo County

Commands