Ticks of Potential Importance on California Cattle


Cattle ticks in California include only a dozen or so species and often are inconspicuous or manageable through application of acaricides (tick poisons). Nevertheless, they represent a significant problem because many transmit tickborne diseases, including several for which surveillance either is inconsistent or impossible (e.g. epizootic bovine abortion for which there is no available diagnostic test).


Moreover, exotic tick introduction is an ongoing threat and could result in introduction of very serious diseases such as heartwater or bovine babesiosis. Additionally, ticks in many areas outside of the US are highly resistant to most or all available tick treatments, a problem that could develop in the US as well. The purpose of this informational page is to introduce the observer to the ticks you might encounter on cattle and provide enough basic information to allow you to distinguish among them and understand the significance of a bite from these ticks.


Boophilus annulatus: exotic

The cattle tick is an excellent vector of bovine babesiosis, but has been eradicated from the United States.


Boophilus microplus: exotic

The tropical cattle fever tick is an important vector of Anaplasma marginale and Texas fever (bovine babesiosis), although this tick is not present in California. All three stages of the tick preferentially feed on cattle.


Dermacentor albipictus

The winter tick is a one-host hard tick, feeding all three stages on horses, deer, or cattle, particularly in coast range and Sierra Nevada foothill sites. The main medical importance can be anemia in severe infestations.


Dermacentor andersoni

The Rocky Mountain wood tick occurs in California only on the Modoc Plateau south to the northern Sierra Nevada range. It feeds as an adult on deer, livestock, dogs, coyotes, and humans. Its medical importance is being a vector of Rocky Mountain spotted fever, Colorado tick fever virus, and tularemia, as well as capable of inducing tick paralysis. It can be experimentally infected with and transmit A. marginale.


Dermacentor occidentalis

The Pacific coast tick feeds on rodents as immatures and on cattle, horses, deer, and occasionally humans as adults. It is found throughout the state with the exception of hottest Central Valley and desert areas.


Dermacentor variabilis

The American dog tick occurs in coast range and Sierra Nevada Mountains as well as cooler and wetter areas of the Central Valley. It feeds as an immature on rodents and lagomorphs and as an adult on dogs and occasionally humans. It can vector Rocky Mountain spotted fever and tularemia, and can induce tick paralysis. It can be a vector of A. marginale to cattle.


Haemaphysalis leporispalustris

The rabbit tick does not feed on cattle, although the agent of bovine ehrlichiosis, A. bovis, was detected in this species and a rabbit-H. leporispalustris epidemiological cycle described on Nantucket Island (Goethert & Telford 2003).


Ixodes pacificus

The Western black-legged tick is found primarily in the Sierra Nevada foothills, coast ranges, and transverse ranges. It preferentially feeds on lizards and small rodents as larvae and nymphs, but will feed on deer, dogs, coyotes, horses, cattle, humans, and many large wildlife species as adults. It can transmit Lyme disease, human and equine granulocytic ehrlichiosis (anaplasmosis), babesiosis, and Powassan encephalitis.


Ornithodorus coriaceus

The Pajahuello (or pajaroello) tick occurs in coast range mountains and Sierra Nevada foothills the entire length of the state, typically in grass where deer and cattle bed. It will feed on many other mammal species, including humans causing a painful, irritated lesion. It is associated with the disease epizootic bovine abortion in cattle.


Otobius megnini

The spinose ear tick is a soft tick that typically feeds in the ears of cattle and horses, and less commonly in humans, dogs, cats, and sheep. It prefers Central Valley and southern dry, warm habitats. Infestation with this tick can cause hair loss and skin irritation in cattle.


Rhipicephalus sanguineus

The brown dog or kennel tick is almost always is associated with dogs in California. It is unusual in that all three stages can occur on dogs and the tick can complete its entire life cycle without any access to wildlife, for example in a kennel. Interestingly, it rarely feeds on cattle in the US, but is reported to do so in other parts of its range, such as in Mexico. It can vector canine ehrlichiosis and babesiosis.