What types of ticks live in Pennsylvania?

Pennsylvania has the deer tick (blacklegged tick), which carries Lyme disease and is established across the state; the American dog tick, which is established; and the lone star tick, which is established and causes alpha-gal syndrome. County-level presence is shown in the table above.

Which Pennsylvania tick carries Lyme disease?

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

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.

Tick Identification in Pennsylvania

The ticks you are most likely to find in Pennsylvania, 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.

Deer tick

Ixodes scapularis

Carries Lyme

Established in Pennsylvania

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

Full deer tick guide →

American dog tick

Dermacentor variabilis

Established in Pennsylvania

Size:: Larger, an apple seed
Look for:: Brown with an ornate off-white mottled shield
Carries:: Rocky Mountain spotted fever, tularemia (rare)

Full american dog tick guide →

Lone star tick

Amblyomma americanum

Established in Pennsylvania

Size:: Medium, rounded
Look for:: Reddish-brown; female has a single white dot on the back
Carries:: Ehrlichiosis, STARI, alpha-gal syndrome

Full lone star tick guide →

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

Full brown dog tick guide →

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

Full gulf coast tick guide →

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

Full asian longhorned tick guide →

Pennsylvania 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 Pennsylvania county

These are the three ticks CDC maps county by county, not the only ticks in Pennsylvania: 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	Gulf Coast tick
Adams County	Established	Established	Reported	Not established
Allegheny County	Established	Reported	Reported	Not established
Armstrong County	Established	Reported	Not established	Not established
Beaver County	Established	Established	Not established	Not established
Bedford County	Established	Established	Reported	Not established
Berks County	Established	Established	Not established	Not established
Blair County	Established	Reported	Not established	Not established
Bradford County	Established	Reported	Not established	Not established
Bucks County	Established	Established	Established	Not established
Butler County	Established	Reported	Not established	Not established
Cambria County	Established	Reported	Reported	Not established
Cameron County	Established	Not established	Not established	Not established
Carbon County	Established	Established	Not established	Not established
Centre County	Established	Reported	Not established	Not established
Chester County	Established	Established	Established	Not established
Clarion County	Established	Reported	Not established	Not established
Clearfield County	Established	Reported	Not established	Not established
Clinton County	Established	Reported	Not established	Not established
Columbia County	Established	Established	Not established	Not established
Crawford County	Established	Reported	Not established	Not established
Cumberland County	Established	Established	Reported	Not established
Dauphin County	Established	Established	Established	Not established
Delaware County	Established	Established	Established	Not established
Elk County	Established	Not established	Not established	Not established
Erie County	Established	Established	Established	Not established
Fayette County	Established	Established	Not established	Not established
Forest County	Established	Reported	Not established	Not established
Franklin County	Established	Established	Established	Not established
Fulton County	Established	Reported	Not established	Not established
Greene County	Established	Established	Not established	Not established
Huntingdon County	Established	Established	Not established	Not established
Indiana County	Established	Reported	Reported	Not established
Jefferson County	Established	Reported	Not established	Not established
Juniata County	Established	Established	Not established	Not established
Lackawanna County	Established	Established	Not established	Not established
Lancaster County	Established	Established	Not established	Not established
Lawrence County	Established	Reported	Not established	Not established
Lebanon County	Established	Established	Established	Not established
Lehigh County	Established	Established	Reported	Not established
Luzerne County	Established	Reported	Not established	Not established
Lycoming County	Established	Established	Not established	Not established
McKean County	Established	Reported	Not established	Not established
Mercer County	Established	Reported	Not established	Not established
Mifflin County	Established	Reported	Not established	Not established
Monroe County	Established	Established	Not established	Not established
Montgomery County	Established	Established	Reported	Not established
Montour County	Established	Established	Not established	Not established
Northampton County	Established	Established	Not established	Not established
Northumberland County	Established	Established	Not established	Not established
Perry County	Established	Established	Not established	Not established
Philadelphia County	Established	Established	Established	Reported
Pike County	Established	Established	Reported	Not established
Potter County	Established	Reported	Not established	Not established
Schuylkill County	Established	Established	Not established	Not established
Snyder County	Established	Established	Reported	Not established
Somerset County	Established	Reported	Not established	Not established
Sullivan County	Established	Established	Not established	Not established
Susquehanna County	Established	Established	Not established	Not established
Tioga County	Established	Not established	Not established	Not established
Union County	Established	Established	Not established	Not established
Venango County	Established	Reported	Not established	Not established
Warren County	Established	Reported	Not established	Not established
Washington County	Established	Established	Not established	Not established
Wayne County	Established	Established	Not established	Not established
Westmoreland County	Established	Reported	Not established	Not established
Wyoming County	Established	Reported	Not established	Not established
York County	Established	Established	Reported	Not established

Lone star ticks and alpha-gal syndrome

The lone star tick is established in Pennsylvania, including Bucks County, Chester County, Dauphin County, Delaware County, Erie County, Franklin County, Lebanon County, Philadelphia County. Its bite can cause alpha-gal syndrome, an allergy to red meat.

Do not overlook the tiny ones

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

Pennsylvania tick risk by town

A daily 0–100 tick-risk score for every town in Pennsylvania.

See Pennsylvania →

Tick identification chart

The national chart, plus identification for other states.

All states →

Frequently asked questions

What types of ticks live in Pennsylvania?: Pennsylvania has the deer tick (blacklegged tick), which carries Lyme disease and is established across the state; the American dog tick, which is established; and the lone star tick, which is established and causes alpha-gal syndrome. County-level presence is shown in the table above.
Which Pennsylvania tick carries Lyme disease?: The deer tick, also called the blacklegged tick, is the tick that spreads Lyme disease in Pennsylvania. The American dog tick and lone star tick do not carry Lyme, though they can transmit other illnesses.
Are there lone star ticks in Pennsylvania?: Yes. The lone star tick is established in Pennsylvania, including Bucks County, Chester County, Dauphin County, Delaware County, Erie County, Franklin County, Lebanon County, Philadelphia County. 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.