Deer tick
Ixodes scapularis
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
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.
Carries Lyme
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)
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
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
Not established in Connecticut
- 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 Connecticut
- Size:
- Larger, an apple seed
- Look for:
- Brown with a marbled silvery-gray ornate shield
- Carries:
- Pacific Coast tick fever, tularemia
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 |
|---|---|---|---|
| Fairfield County | Established | Established | Established |
| Hartford County | Established | Established | Not established |
| Litchfield County | Established | Established | Not established |
| Middlesex County | Established | Established | Not established |
| New Haven County | Established | Established | Established |
| New London County | Established | Established | Established |
| Tolland County | Established | Established | Not established |
| Windham County | Established | Established | Reported |
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.
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.