Deer tick
Ixodes scapularis
Not established in Idaho
- Size:
- Small, a sesame seed (nymph: a poppy seed)
- Look for:
- Reddish-orange body, solid dark shield, black legs, no pattern
- Carries:
- Lyme, babesiosis, anaplasmosis, Powassan
Tick Identification in Idaho
The ticks you are most likely to find in Idaho, with photos and the size, color, and markings that tell them apart. Only the deer tick carries Lyme disease. Below the chart, see which types live in your county.
Carries Lyme
American dog tick
Dermacentor variabilis
Reported in Idaho
- Size:
- Larger, an apple seed
- Look for:
- Brown with an ornate off-white mottled shield
- Carries:
- Rocky Mountain spotted fever, tularemia (rare)
Lone star tick
Amblyomma americanum
Not established in Idaho
- Size:
- Medium, rounded
- Look for:
- Reddish-brown; female has a single white dot on the back
- Carries:
- Ehrlichiosis, STARI, alpha-gal syndrome
Brown dog tick
Rhipicephalus sanguineus
Found nationwide, the one tick that infests homes and kennels indoors
- Size:
- Medium, narrow body that tapers toward the head
- Look for:
- Uniform reddish-brown, no ornate markings
- Carries:
- Rocky Mountain spotted fever, canine diseases
Gulf Coast tick
Amblyomma maculatum
A southern tick spreading north into the mid-Atlantic
- Size:
- Large, bigger than a lone star
- Look for:
- Silvery ornate markings on the shield, no single dot
- Carries:
- Rickettsia parkeri spotted fever
Asian longhorned tick
Haemaphysalis longicornis
A newer arrival, established in the mid-Atlantic and spreading north
- Size:
- Small and plain, often found in large numbers
- Look for:
- Reddish-brown with no markings
- Carries:
- Mainly a livestock threat; human disease risk under study
Rocky Mountain wood tick
Dermacentor andersoni
Established in Idaho
- Size:
- Larger, an apple seed
- Look for:
- Brown with an ornate off-white and gray marbled shield
- Carries:
- Rocky Mountain spotted fever, Colorado tick fever, tularemia
Pacific Coast tick
Dermacentor occidentalis
Not established in Idaho
- Size:
- Larger, an apple seed
- Look for:
- Brown with a marbled silvery-gray ornate shield
- Carries:
- Pacific Coast tick fever, tularemia
Idaho establishment is shown for the three ticks CDC tracks by county; the others carry a regional range note. Source: CDC tick surveillance (ArboNET Tick Module), 2025. County surveillance is coarse: “not established” is a lack of records, not proof a tick is absent.
Deer, dog and lone star ticks by Idaho county
These are the three ticks CDC maps county by county, not the only ticks in Idaho: the brown dog, Gulf Coast, and Asian longhorned ticks are in the chart above. Tap a county for its daily tick-risk detail.
| County | Deer tick | American dog tick | Lone star tick |
|---|---|---|---|
| Ada County | Not established | Reported | Not established |
| Adams County | Not established | Reported | Not established |
| Bannock County | Not established | Reported | Not established |
| Bear Lake County | Not established | Reported | Not established |
| Benewah County | Not established | Reported | Not established |
| Bingham County | Not established | Reported | Not established |
| Blaine County | Not established | Reported | Not established |
| Boise County | Not established | Reported | Not established |
| Bonner County | Not established | Reported | Not established |
| Bonneville County | Not established | Reported | Not established |
| Boundary County | Not established | Reported | Not established |
| Butte County | Not established | Reported | Not established |
| Camas County | Not established | Reported | Not established |
| Canyon County | Not established | Reported | Not established |
| Caribou County | Not established | Reported | Not established |
| Cassia County | Not established | Reported | Not established |
| Clark County | Not established | Reported | Not established |
| Clearwater County | Not established | Reported | Not established |
| Custer County | Not established | Reported | Not established |
| Elmore County | Not established | Reported | Not established |
| Franklin County | Not established | Reported | Not established |
| Fremont County | Not established | Reported | Not established |
| Gem County | Not established | Reported | Not established |
| Gooding County | Not established | Reported | Not established |
| Idaho County | Not established | Reported | Not established |
| Jefferson County | Not established | Reported | Not established |
| Jerome County | Not established | Reported | Not established |
| Kootenai County | Not established | Reported | Not established |
| Latah County | Not established | Reported | Not established |
| Lemhi County | Not established | Reported | Not established |
| Lewis County | Not established | Reported | Not established |
| Lincoln County | Not established | Reported | Not established |
| Madison County | Not established | Reported | Not established |
| Minidoka County | Not established | Reported | Not established |
| Nez Perce County | Not established | Reported | Not established |
| Oneida County | Not established | Reported | Not established |
| Owyhee County | Not established | Reported | Not established |
| Payette County | Not established | Reported | Not established |
| Power County | Not established | Reported | Not established |
| Shoshone County | Not established | Reported | Not established |
| Teton County | Not established | Reported | Not established |
| Twin Falls County | Not established | Reported | Not established |
| Valley County | Not established | Reported | Not established |
| Washington County | Not established | Reported | Not established |
Do not overlook the tiny ones
Nymph deer ticks are the size of a poppy seed and cause most Lyme cases in Idaho 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 Idaho?
- Idaho has the deer tick (blacklegged tick), which carries Lyme disease and is not established 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 Idaho tick carries Lyme disease?
- The deer tick, also called the blacklegged tick, is the tick that spreads Lyme disease in Idaho. The American dog tick and lone star tick do not carry Lyme, though they can transmit other illnesses.
- Are there lone star ticks in Idaho?
- The lone star tick is not established in Idaho 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.