Tick Identification in California

Deer, dog and lone star ticks by California county

These are the three ticks CDC maps county by county, not the only ticks in California: the brown dog, Gulf Coast, and Asian longhorned ticks are in the chart above. Tap a county for its daily tick-risk detail.

Do not overlook the tiny ones

Nymph deer ticks are the size of a poppy seed and cause most Lyme cases in California because they are so easy to miss. When you check for ticks, look for the small ones too, especially in June and July.

Frequently asked questions

What types of ticks live in California?

California has the deer tick (blacklegged tick), which carries Lyme disease and is reported across the state; the American dog tick, which is reported; and the lone star tick, which is not established and causes alpha-gal syndrome. County-level presence is shown in the table above.

Which California tick carries Lyme disease?

The deer tick, also called the blacklegged tick, is the tick that spreads Lyme disease in California. The American dog tick and lone star tick do not carry Lyme, though they can transmit other illnesses.

Are there lone star ticks in California?

The lone star tick is not established in California in current CDC county surveillance, but ranges are expanding northward, so this can change. It causes alpha-gal syndrome, a red-meat allergy.

How can I tell these ticks apart?

Use size, color, and legs. The deer tick is small with a reddish-orange body, a solid dark shield, and black legs. The American dog tick is larger and brown with an ornate off-white mottled shield. The female lone star tick has a single white dot on her back. The chart above shows each one.