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American Dog Tick (Dermacentor variabilis)

This tick is found throughout the United States as well as parts of Canada and Mexico. Within California it is most frequently found along the coastal ranges and central valley. This species is an important vector of Rocky Mountain Spotted fever rickettsia and the bacterium responsible for Tularemia. The saliva of this tick has also been known to cause tick paralysis.

The immature stages feed primarily on rodents, rabbits and hares, while the adults prefer large mammals, especially dogs, coyotes and humans.

Life cycle can be completed in less than one year or take longer than two years if suitable hosts are not available. Adults are present year-round while nymphs and larvae are most active late winter to summer. Adult females may take up to 13 days to complete feeding on a host and can produce as many as 6500 eggs during their lifetime. Immature ticks are capable of surviving extreme winter temperatures.

Dogs are the preferred host although adults will feed on humans and many other species of large wild and domesticated mammals. Larvae and nymphs tend to feed on rodents and rabbits.

Important vector of Rocky Mountain Spotted Fever, especially in the Eastern United States. Vector of Tularemiato humans. Known to cause tick paralysis.