How do you identify a tick?

Look at three things: size, color, and markings. A deer tick is small with a reddish-orange body, a solid dark shield, and black legs. An American dog tick is larger and brown with an ornate off-white mottled shield. A lone star tick is reddish-brown, and the female has a single white dot on her back. Only the deer tick carries Lyme disease.

Which tick carries Lyme disease?

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

What is the difference between a nymph and an adult tick?

Nymphs are immature ticks about the size of a poppy seed, while adults are roughly a sesame seed or larger. Nymph deer ticks cause most Lyme cases because they are so small they are easy to miss. Both nymphs and adults can bite and transmit disease.

Can you identify a tick from a photo?

Often, yes, from size, color, leg color, and markings like the lone star tick's white dot. Use the identification chart above to compare. If you are unsure or feel unwell after a bite, save the tick in a sealed bag and contact a healthcare professional or your county health department.

Tick Identification Chart

The ticks that bite people in the Northeast, side by side. Use the photos, size, and markings below to tell them apart, and remember the one that matters most: only the deer tick carries Lyme disease.

Deer tick

Ixodes scapularis

Carries Lyme

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

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

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 →

Photo credits in each guide. Disease and range data: CDC tick surveillance (ArboNET Tick Module), 2025.

How to identify a tick in three steps

1. Size

How big is it?

A poppy seed is a nymph. A sesame seed is an adult deer tick. Noticeably bigger, an apple seed, points to a dog tick. A tick swollen with blood is engorged and harder to ID by size.

2. Color and markings

Any pattern?

A solid dark shield with no pattern is a deer tick. An ornate off-white mottled shield is a dog tick. A single white dot in the center of the back is a female lone star tick.

3. Legs

What color are the legs?

Black legs point to the deer tick (the blacklegged tick). Brown legs point to the dog tick or lone star tick. Combined with size and markings, this usually settles it.

Nymph vs. adult: why size matters

Ticks bite at two life stages. Nymphs are immature and tiny, about a poppy seed, and they cause most Lyme disease cases precisely because they are so easy to miss. Adults are larger, about a sesame seed or bigger. Both can transmit disease, so a tick check should look for the small ones too, especially in early summer when nymph deer ticks peak.

Know which ticks are active where you live

TickZone gives every town a daily 0–100 tick-risk score and lists the species established in your county.

Check your town →

Frequently asked questions

How do you identify a tick?: Look at three things: size, color, and markings. A deer tick is small with a reddish-orange body, a solid dark shield, and black legs. An American dog tick is larger and brown with an ornate off-white mottled shield. A lone star tick is reddish-brown, and the female has a single white dot on her back. Only the deer tick carries Lyme disease.
Which tick carries Lyme disease?: The deer tick, also called the blacklegged tick (Ixodes scapularis), is the tick that spreads Lyme disease. The American dog tick and the lone star tick do not carry Lyme, though they can transmit other illnesses.
What is the difference between a nymph and an adult tick?: Nymphs are immature ticks about the size of a poppy seed, while adults are roughly a sesame seed or larger. Nymph deer ticks cause most Lyme cases because they are so small they are easy to miss. Both nymphs and adults can bite and transmit disease.
Can you identify a tick from a photo?: Often, yes, from size, color, leg color, and markings like the lone star tick's white dot. Use the identification chart above to compare. If you are unsure or feel unwell after a bite, save the tick in a sealed bag and contact a healthcare professional or your county health department.