What types of ticks live in Connecticut?

Connecticut 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 Connecticut tick carries Lyme disease?

The deer tick, also called the blacklegged tick, is the tick that spreads Lyme disease in Connecticut. 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 Connecticut

The ticks you are most likely to find in Connecticut, 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 Connecticut

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 Connecticut

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 Connecticut

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 →

Connecticut 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 Connecticut county

These are the three ticks CDC maps county by county, not the only ticks in Connecticut: 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
Fairfield County	Established	Established	Established	Established
Hartford County	Established	Established	Not established	Not established
Litchfield County	Established	Established	Not established	Not established
Middlesex County	Established	Established	Not established	Not established
New Haven County	Established	Established	Established	Reported
New London County	Established	Established	Established	Not established
Tolland County	Established	Established	Not established	Not established
Windham County	Established	Established	Reported	Not established

Lone star ticks and alpha-gal syndrome

The lone star tick is established in Connecticut, including Fairfield County, New Haven County, New London 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 Connecticut because they are so easy to miss. When you check for ticks, look for the small ones too, especially in June and July.

Connecticut tick risk by town

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

See Connecticut →

Tick identification chart

The national chart, plus identification for other states.

All states →

Frequently asked questions

What types of ticks live in Connecticut?: Connecticut 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 Connecticut tick carries Lyme disease?: The deer tick, also called the blacklegged tick, is the tick that spreads Lyme disease in Connecticut. The American dog tick and lone star tick do not carry Lyme, though they can transmit other illnesses.
Are there lone star ticks in Connecticut?: Yes. The lone star tick is established in Connecticut, including Fairfield County, New Haven County, New London 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.