HARD TICKS

IXODIDAE

The hard ticks (Ixodidae) identified below pose health risks for both humans and animals in the Pacific Southwest. Hard ticks are recognized by their mouth parts that project forward from the body and for having a hard outer shell, also known as scutum.

WESTERN BLACKLEGGED TICK

Ixodes pacificus

Regions Where They Live

Western blacklegged ticks can be found in northern California, along the Pacific Coast of the US.

Visit the CDC website for more information.

Pathogens & Diseases

Western blacklegged ticks can carry and spread pathogens that are responsible for diseases in both humans and animals.

View CDPH Seasonal Risk of Exposure to Infected Western Blacklegged Ticks in California

Life Stages

Photo: Bay Area Lyme Foundation

Life Cycle & Hosts

AMERICAN DOG TICK
Dermacentor variabilis

Regions Where They Live

American dog ticks are widely distributed east of the Rocky Mountains. They can also be found in limited areas on the Pacific Coast.

Visit the CDC website for more information.

Pathogens & Diseases

American dog ticks can carry and spread pathogens that are responsible for diseases in both humans and animals.

Life Stages

From left to right:

  • Adult female
  • Adult male
  • Nymph
  • Larva

ROCKY MOUNTAIN
WOOD TICK

Dermacentor andersoni

Regions Where They Live

Rocky Mountain wood ticks can be found in Rocky Mountain states and southwestern Canada from elevations of 4,000 to 10,500 feet.

Visit the CDC website for more information.

Pathogens & Diseases

Rocky Mountain wood ticks can carry and spread pathogens that are responsible for diseases in both humans and animals.

BROWN DOG TICK
Rhipicephalus sanguineus

Regions Where They Live

Brown dog ticks can be found worldwide.

Visit the CDC website for more information.

Pathogens & Diseases

Brown dog ticks can carry and spread pathogens that are responsible for diseases in both humans and animals. Brown dog ticks are primary vectors for Rickettsia rickettsii (pathogen) transmission in the southwestern United States and along the U.S.-Mexico border.

Life Cycle & Hosts

The brown dog tick is unique in that it can complete its entire life cycle indoors. In contrast to the other hard ticks, the risk of coming into contact with the brown dog tick is not necessarily from hiking or other outside activities.

View full CDC fact sheet.

PACIFIC COAST TICK
Dermacentor occidentalis

Regions Where They Live

Pacific Coast ticks can be found predominantly in shrublands, chaparral, and along trails from Oregon to northern Baja California and Mexico.

Visit Tick Encounter for more information.

Pathogens & Diseases

Pacific coast ticks can carry and spread pathogens that are responsible for diseases in both humans and animals.

TICK RESOURCES

Learn about the tick species that pose health risks for both humans and animals in the region and view public health information on ticks.

GOT TICKS? CONTACT BiTeRS!

The Border Tick and Rickettsia Surveillance (BiTeRS) program of PacVec offers services to enhance surveillance for ticks and tick-borne pathogens of human health concern in California and Arizona.

The Pacific Southwest Regional Center of Excellence in Vector-Borne Diseases is supported through Cooperative Agreement Number 1U01CK000649 between the Centers for Disease Control and Prevention (CDC) and the University of California, Davis.

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