TickZone

Tick Identification in Illinois

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

Female deer tick (blacklegged tick) on a green leaf, with a reddish-orange body, dark shield, and black legs, no white markings

Deer tick

Ixodes scapularis

Carries Lyme

Established in Illinois

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 →
Female American dog tick with an ornate off-white and brown mottled shield behind the head

American dog tick

Dermacentor variabilis

Established in Illinois

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 →
Female lone star tick on a green blade of grass, reddish-brown with a single bright white dot in the center of its back

Lone star tick

Amblyomma americanum

Reported in Illinois

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 →
Female brown dog tick, uniform reddish-brown with no distinct markings

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 →
Female Gulf Coast tick with an ornate silvery patterned shield

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 →
Female Asian longhorned tick, small and uniform reddish-brown with no markings

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 →

Illinois 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 Illinois county

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

CountyDeer tickAmerican dog tickLone star tick
Adams CountyEstablishedEstablishedReported
Alexander CountyEstablishedEstablishedReported
Bond CountyEstablishedEstablishedReported
Boone CountyEstablishedEstablishedReported
Brown CountyEstablishedEstablishedReported
Bureau CountyEstablishedEstablishedReported
Calhoun CountyEstablishedEstablishedReported
Carroll CountyEstablishedEstablishedReported
Cass CountyEstablishedEstablishedReported
Champaign CountyEstablishedEstablishedReported
Christian CountyEstablishedEstablishedReported
Clark CountyEstablishedEstablishedReported
Clay CountyEstablishedEstablishedReported
Clinton CountyEstablishedEstablishedReported
Coles CountyEstablishedEstablishedReported
Cook CountyEstablishedEstablishedReported
Crawford CountyEstablishedEstablishedReported
Cumberland CountyEstablishedEstablishedReported
De Witt CountyEstablishedEstablishedReported
DeKalb CountyEstablishedEstablishedReported
Douglas CountyEstablishedEstablishedReported
DuPage CountyEstablishedEstablishedReported
Edgar CountyEstablishedEstablishedReported
Edwards CountyEstablishedEstablishedReported
Effingham CountyEstablishedEstablishedReported
Fayette CountyEstablishedEstablishedReported
Ford CountyEstablishedEstablishedReported
Franklin CountyEstablishedEstablishedReported
Fulton CountyEstablishedEstablishedReported
Gallatin CountyEstablishedEstablishedReported
Greene CountyEstablishedEstablishedReported
Grundy CountyEstablishedEstablishedReported
Hamilton CountyEstablishedEstablishedReported
Hancock CountyEstablishedEstablishedReported
Hardin CountyEstablishedEstablishedReported
Henderson CountyEstablishedEstablishedReported
Henry CountyEstablishedEstablishedReported
Iroquois CountyEstablishedEstablishedReported
Jackson CountyEstablishedEstablishedReported
Jasper CountyEstablishedEstablishedReported
Jefferson CountyEstablishedEstablishedReported
Jersey CountyEstablishedEstablishedReported
Jo Daviess CountyEstablishedEstablishedReported
Johnson CountyEstablishedEstablishedReported
Kane CountyEstablishedEstablishedReported
Kankakee CountyEstablishedEstablishedReported
Kendall CountyEstablishedEstablishedReported
Knox CountyEstablishedEstablishedReported
Lake CountyEstablishedEstablishedReported
LaSalle CountyEstablishedEstablishedReported
Lawrence CountyEstablishedEstablishedReported
Lee CountyEstablishedEstablishedReported
Livingston CountyEstablishedEstablishedReported
Logan CountyEstablishedEstablishedReported
Macon CountyEstablishedEstablishedReported
Macoupin CountyEstablishedEstablishedReported
Madison CountyEstablishedEstablishedReported
Marion CountyEstablishedEstablishedReported
Marshall CountyEstablishedEstablishedReported
Mason CountyEstablishedEstablishedReported
Massac CountyEstablishedEstablishedReported
McDonough CountyEstablishedEstablishedReported
McHenry CountyEstablishedEstablishedReported
McLean CountyEstablishedEstablishedReported
Menard CountyEstablishedEstablishedReported
Mercer CountyEstablishedEstablishedReported
Monroe CountyEstablishedEstablishedReported
Montgomery CountyEstablishedEstablishedReported
Morgan CountyEstablishedEstablishedReported
Moultrie CountyEstablishedEstablishedReported
Ogle CountyEstablishedEstablishedReported
Peoria CountyEstablishedEstablishedReported
Perry CountyEstablishedEstablishedReported
Piatt CountyEstablishedEstablishedReported
Pike CountyEstablishedEstablishedReported
Pope CountyEstablishedEstablishedReported
Pulaski CountyEstablishedEstablishedReported
Putnam CountyEstablishedEstablishedReported
Randolph CountyEstablishedEstablishedReported
Richland CountyEstablishedEstablishedReported
Rock Island CountyEstablishedEstablishedReported
Saline CountyEstablishedEstablishedReported
Sangamon CountyEstablishedEstablishedReported
Schuyler CountyEstablishedEstablishedReported
Scott CountyEstablishedEstablishedReported
Shelby CountyEstablishedEstablishedReported
St. Clair CountyEstablishedEstablishedReported
Stark CountyEstablishedEstablishedReported
Stephenson CountyEstablishedEstablishedReported
Tazewell CountyEstablishedEstablishedReported
Union CountyEstablishedEstablishedReported
Vermilion CountyEstablishedEstablishedReported
Wabash CountyEstablishedEstablishedReported
Warren CountyEstablishedEstablishedReported
Washington CountyEstablishedEstablishedReported
Wayne CountyEstablishedEstablishedReported
White CountyEstablishedEstablishedReported
Whiteside CountyEstablishedEstablishedReported
Will CountyEstablishedEstablishedReported
Williamson CountyEstablishedEstablishedReported
Winnebago CountyEstablishedEstablishedReported
Woodford CountyEstablishedEstablishedReported

Lone star ticks and alpha-gal syndrome

The lone star tick is reported in Illinois. 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 Illinois because they are so easy to miss. When you check for ticks, look for the small ones too, especially in June and July.

Illinois tick risk by town

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

See Illinois →

Tick identification chart

The national chart, plus identification for other states.

All states →

Frequently asked questions

What types of ticks live in Illinois?
Illinois 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 reported and causes alpha-gal syndrome. County-level presence is shown in the table above.
Which Illinois tick carries Lyme disease?
The deer tick, also called the blacklegged tick, is the tick that spreads Lyme disease in Illinois. The American dog tick and lone star tick do not carry Lyme, though they can transmit other illnesses.
Are there lone star ticks in Illinois?
Yes. The lone star tick is reported in Illinois. 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.