Deer tick
Ixodes scapularis
Reported in Oregon
- 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 Oregon
The ticks you are most likely to find in Oregon, 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 Oregon
- 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 Oregon
- 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 Oregon
- 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
Reported in Oregon
- Size:
- Larger, an apple seed
- Look for:
- Brown with a marbled silvery-gray ornate shield
- Carries:
- Pacific Coast tick fever, tularemia
Oregon 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 Oregon county
These are the three ticks CDC maps county by county, not the only ticks in Oregon: 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 |
|---|---|---|---|
| Baker County | Reported | Reported | Not established |
| Benton County | Reported | Reported | Not established |
| Clackamas County | Reported | Reported | Not established |
| Clatsop County | Reported | Reported | Not established |
| Columbia County | Reported | Reported | Not established |
| Coos County | Reported | Reported | Not established |
| Crook County | Reported | Reported | Not established |
| Curry County | Reported | Reported | Not established |
| Deschutes County | Reported | Reported | Not established |
| Douglas County | Reported | Reported | Not established |
| Gilliam County | Reported | Reported | Not established |
| Grant County | Reported | Reported | Not established |
| Harney County | Reported | Reported | Not established |
| Hood River County | Reported | Reported | Not established |
| Jackson County | Reported | Reported | Not established |
| Jefferson County | Reported | Reported | Not established |
| Josephine County | Reported | Reported | Not established |
| Klamath County | Reported | Reported | Not established |
| Lake County | Reported | Reported | Not established |
| Lane County | Reported | Reported | Not established |
| Lincoln County | Reported | Reported | Not established |
| Linn County | Reported | Reported | Not established |
| Malheur County | Reported | Reported | Not established |
| Marion County | Reported | Reported | Not established |
| Morrow County | Reported | Reported | Not established |
| Multnomah County | Reported | Reported | Not established |
| Polk County | Reported | Reported | Not established |
| Sherman County | Reported | Reported | Not established |
| Tillamook County | Reported | Reported | Not established |
| Umatilla County | Reported | Reported | Not established |
| Union County | Reported | Reported | Not established |
| Wallowa County | Reported | Reported | Not established |
| Wasco County | Reported | Reported | Not established |
| Washington County | Reported | Reported | Not established |
| Wheeler County | Reported | Reported | Not established |
| Yamhill County | Reported | 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 Oregon 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 Oregon?
- Oregon 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 Oregon tick carries Lyme disease?
- The deer tick, also called the blacklegged tick, is the tick that spreads Lyme disease in Oregon. The American dog tick and lone star tick do not carry Lyme, though they can transmit other illnesses.
- Are there lone star ticks in Oregon?
- The lone star tick is not established in Oregon 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.