Hard Ticks (Ixodidae)
Western Black-legged Tick (Ixodes pacificus)
Western black-legged ticks can transmit Borrelia burgdorferi, the bacteria that causes Lyme disease. It can also transmit the pathogen that causes anaplasmosis. These ticks are mainly found in Western Washington as well as along the eastern slopes of the Cascade Mountains. They live in forested, oak savannah, or brushy areas. See CDC's map of where Ixodes pacificus has been found.
Female western black-legged tick, Ixodes pacificus
Photo: James Gathany, CDC
Western black-legged ticks, Ixodes pacificus, on a finger. From left to right: nymph, adult male, and adult female.
Photo: California Department of Public Health
Three western blacklegged ticks, Ixodes pacificus, on a ruler. The tick on the top is a fed, or engorged, female. A tick's body slowly enlarges to accommodate the amount of blood ingested. Engorged ticks that are still attached and feeding often have either a gray or light tan color. The bottom left tick is an unfed female. The tick on the bottom right is an unfed male.
Photo: California Department of Public Health
Western Dog Tick
Western dog ticks live primarily in eastern and parts of southwest Washington. They prefer woodland areas, medium height grasses and shrubs between wetlands and woods, and sunny or open areas around woods. Adult western dog ticks are common pests of dogs while larvae and nymphs prefer feeding on small mammals like rodents and rabbits.
Female western dog tick
Photo: James Gathany, CDC
Rocky Mountain Wood Tick (Dermacentor andersoni)
The Rocky Mountain wood tick’s life cycle may require up to two to three years for completion. Adult wood ticks feed primarily on large mammals while the larvae and nymphs feed on small rodents and rabbits. These ticks are found primarily on the eastern side of the state. They prefer woodland areas, medium height grasses and shrubs between wetlands and woods, and sunny or open areas along the edge of woods. Rocky Mountain wood ticks and western dog ticks look very similar to each other.
Female Rocky Mountain wood tick, Dermacentor andersoni
Photo: James Gathany, CDC
Male Rocky Mountain wood tick, Dermacentor andersoni
Photo: James Gathany, CDC
Soft Ticks (Argasidae)
Ornithodoros hermsi
Ornithodoros hermsi is the vector for tick-borne relapsing fever. Tick-borne relapsing fever is usually linked to sleeping in rustic, rodent-infested cabins in mountainous areas. Because soft ticks usually feed at night and remain attached for a very short time, most people never realize a tick bit them.
Soft Tick, Ornithodorus hermsi
Photo: Anna Perez, CDC