Tick Identification Guide
Learn About Common Human-Biting Ticks in the United States
Ticks are small arachnids found in many parts of the United States. Different tick species live in different regions and may transmit different bacteria, viruses, or parasites through their bites.
Use this guide to learn about ticks that may bite people in the United States, how to recognize some of their common features, where they are found, and the diseases or health conditions associated with them.
Important: Tick appearance can vary depending on species, life stage, sex, and whether the tick has fed. Photos and visual characteristics can help with general identification, but appearance alone should not be used to determine whether a tick carried a disease-causing pathogen or whether an infection occurred.
Found an Attached Tick?
Remove it as soon as possible. Do not delay removal while trying to identify the tick.
Use clean, fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible. Pull upward with steady, even pressure without twisting or jerking.
After removal, clean the bite area and your hands with soap and water, rubbing alcohol, or hand sanitizer.
If you develop a rash, fever, or other concerning symptoms within the following days or weeks, contact a healthcare provider and mention the known or possible tick exposure.
Asian Longhorned Tick
Haemaphysalis longicornis
The Asian longhorned tick is an invasive tick species first reported in the United States in 2017.
How to Identify:
Asian longhorned ticks are generally small and reddish-brown to dark brown without conspicuous decorative markings. They can be difficult to distinguish from other small brown ticks based on appearance alone.
Where Found:
Asian longhorned ticks have been detected in multiple states in the eastern and central United States. Their U.S. distribution continues to be monitored, and USDA maintains updated information on where they have been found.
Human Health Relevance:
In other parts of the world, Asian longhorned ticks can transmit pathogens that cause serious illnesses in people and animals.
In the United States, however, researchers do not yet know whether or how often these ticks transmit disease-causing pathogens to people under natural conditions.
Laboratory research has shown that Asian longhorned ticks can acquire and transmit Rickettsia rickettsii, the bacterium that causes Rocky Mountain spotted fever, but this bacterium has not been found naturally infecting U.S. Asian longhorned tick populations in a way that establishes them as a natural human vector
Laboratory studies also indicate that this tick is unlikely to contribute significantly to transmission of the bacteria that cause Lyme disease in the United States.
Research is ongoing.
Details:
Asian longhorned ticks have been found on livestock, pets, wildlife, and people. Females can reproduce without mating through a process known as parthenogenesis, allowing populations to increase rapidly under favorable conditions.
Compared with several common native U.S. ticks—including blacklegged ticks, lone star ticks, and American dog ticks—the Asian longhorned tick appears to be less attracted to people.
Black-Legged Tick (Ixodes scapularis):
Also commonly called the deer tick, the blacklegged tick is one of the most medically important ticks in the United States.
How to Identify:
Adult females typically have dark legs, a dark shield near the head, and a reddish-orange to reddish-brown abdomen. Adult males are generally darker overall. Nymphs are extremely small and can be difficult to recognize.
Where Found:
Widely distributed across the eastern United States.
Transmits:
- Lyme disease — Borrelia burgdorferi and Borrelia mayonii
- Anaplasmosis — Anaplasma phagocytophilum
- Babesiosis — Babesia microti
- Hard tick relapsing fever — Borrelia miyamotoi
- Ehrlichiosis caused by Ehrlichia muris eauclairensis
- Powassan virus disease
American Dog Tick (Dermacentor variabilis):
Dermacentor variabilis
The American dog tick is a common human-biting tick, particularly in the eastern United States.
How to Identify:
Adult ticks are brown with distinctive pale gray or silvery-white markings. Adult females generally have pale markings on the shield behind the mouthparts, while males have more extensive mottled markings across the back.
Where Found:
Dermacentor variabilis is widely distributed east of the Rocky Mountains and also occurs in limited areas west of the Rockies.
CDC also recognizes the closely related Dermacentor similis in areas west of the Rocky Mountains. Additional research is needed to better understand the role of D. similis in human disease transmission.
Transmits:
- Rocky Mountain spotted fever
- Tularemia
Human-Biting Activity: Adult females are most likely to bite people. Risk of bites is generally highest during spring and summer.
Lone Star Tick (Amblyomma americanum):
Amblyomma americanum
The lone star tick is an aggressive human-biting tick found across a large portion of the United States.
How to Identify:
Adult females have a distinctive single white or pale spot—the “lone star”—in the center of the back. Adult males have pale markings around the outer portion of the body but do not have the female's single central white spot.
Where Found:
Widely distributed in the Northeast, South, and Midwest of the United States.
Transmits:
- Ehrlichiosis — Ehrlichia chaffeensis and Ehrlichia ewingii
- Tularemia — Francisella tularensis
- Heartland virus disease
- Bourbon virus disease
- Southern Tick-Associated Rash Illness (STARI): The cause of STARI remains unknown, but the condition is specifically associated with lone star tick bites.
- Alpha-Gal Syndrome (AGS): In the United States, the lone star tick is the tick most often associated with alpha-gal syndrome.
Important: Redness or irritation immediately around a lone star tick bite does not necessarily mean an infection has occurred.
Rocky Mountain Wood Tick (Dermacentor andersoni):
Dermacentor andersoni
The Rocky Mountain wood tick is an important human-biting tick in mountainous areas of the western United States and southwestern Canada.
How to Identify:
Adult ticks are brown with pale gray, white, or silvery markings. Their patterned appearance can resemble other Dermacentor ticks, so visual identification to species may sometimes be difficult.
Where Found:
Rocky Mountain states and southwestern Canada, particularly at elevations of approximately 4,000–10,500 feet.
Transmits:
- Rocky Mountain spotted fever — Rickettsia rickettsii
- Colorado tick fever — Colorado tick fever virus
- Tularemia — Francisella tularensis
Human-Biting Activity: Adult ticks are primarily associated with transmission of pathogens to people.
Gulf Coast Tick (Amblyomma maculatum):
Amblyomma maculatum
The Gulf Coast tick is an ornate tick associated with a spotted fever rickettsiosis.
How to Identify:
Adults are generally brown with pale or silvery markings. They have relatively long mouthparts compared with ticks in the genus Dermacentor.
Where Found:
Primarily in the southeastern United States, with focal populations in the Northeast, Midwest, and Southwest.
Transmits:
- Rickettsia parkeri, which causes Rickettsia parkeri rickettsiosis, a type of spotted fever rickettsiosis
Brown Dog Tick (Rhipicephalus sanguineus):
Rhipicephalus sanguineus
Unlike many ticks that are primarily associated with outdoor environments, brown dog ticks can live and reproduce in and around homes, kennels, and other places where dogs are present.
How to Identify:
Brown dog ticks are generally reddish-brown to dark brown and lack the ornate white or silver markings seen on some Dermacentor and Amblyomma ticks.
Where Found:
Worldwide, including throughout the United States.
Transmits to People:
- Rocky Mountain spotted fever, particularly in parts of the southwestern United States and along the U.S.–Mexico border
Brown dog ticks are unusual among many U.S. ticks because they can complete their life cycle indoors and can establish infestations in homes, kennels, and similar environments.
Western Black-Legged Tick (Ixodes pacificus):
The western blacklegged tick is an important human-biting tick along the Pacific Coast.
How to Identify:
Adult females generally have dark legs and a dark shield with a reddish-brown abdomen. Their appearance can resemble that of the eastern blacklegged tick. Nymphs are very small and can be difficult to identify without magnification.
Where Found:
Along the Pacific Coast of the United States, particularly in northern California.
Transmits:
- Lyme disease — Borrelia burgdorferi
- Anaplasmosis — Anaplasma phagocytophilum
- Hard tick relapsing fever — Borrelia miyamotoi
Groundhog Tick / Woodchuck Tick (Ixodes cookei):
The groundhog tick, also known as the woodchuck tick, primarily feeds on wildlife and only occasionally bites people.
How to Identify:
Groundhog ticks are small, brown to reddish-brown hard ticks. Because they can resemble other Ixodes species, reliable species-level identification may be difficult based on a photograph alone.
Where Found:
Throughout much of the eastern half of the United States.
Transmits:
- Powassan virus, which can cause Powassan virus disease
Groundhog ticks bite humans less frequently than blacklegged ticks.
Pacific Coast Tick (Dermacentor occidentalis):
Dermacentor occidentalis
The Pacific Coast tick is a human-biting Dermacentor tick found along portions of the western United States.
How to Identify:
Adult Pacific Coast ticks have an ornate appearance with pale gray, whitish, or silvery markings against a darker brown background. They can resemble other Dermacentor species, so species-level identification from appearance alone may be difficult.
Where Found:
Along the western coastline of the United States, particularly in California, Oregon, and Washington. .
Transmits:
- Rickettsia rickettsii subsp. californica — the bacterium that causes Pacific Coast tick fever
Details: Pacific Coast tick fever is a spotted fever rickettsiosis. Illness commonly includes an eschar—a dark scab or lesion at the site of the tick bite—followed by symptoms that may include fever, headache, muscle aches, fatigue, and swollen lymph nodes. A rash may occur but is less common than with some other spotted fever illnesses.
SOFT TICK Ornithodoros spp:
Ornithodoros species
Soft ticks differ considerably in appearance and feeding behavior from the hard ticks most people commonly encounter outdoors.
How to Identify:
Soft ticks typically have a leathery, wrinkled-looking body rather than the hard dorsal shield found on hard ticks. Their mouthparts are located on the underside of the body and generally cannot be seen when looking at the tick from above.
Where Found:
Soft ticks capable of transmitting relapsing-fever Borrelia occur in parts of the United States, particularly in western and southwestern regions.
Exposure to Ornithodoros hermsi is often associated with rodent-infested rustic cabins in mountainous areas.
Ornithodoros turicata occurs in parts of the southwestern United States and can be associated with caves and animal burrows.
Transmits:
- Borrelia hermsii
- Borrelia turicatae
- Other relapsing-fever Borrelia species
Important Terminology: Soft tick relapsing fever was previously commonly called tickborne relapsing fever (TBRF). The term STRF helps distinguish infections transmitted by soft ticks from hard tick relapsing fever (HTRF) caused primarily by Borrelia miyamotoi.
Details: Unlike many hard ticks, soft ticks often feed very quickly—sometimes for less than 30 minutes. Their bites are usually painless, and many people never realize they were bitten.
In the United States, STRF exposures often occur when people stay overnight in rodent-infested cabins. Some infections are also associated with cave exposure.
Which Ticks Most Commonly Bite People?
Many tick species can bite humans, but they are not encountered equally often.
Among hard ticks documented from people in the United States, the species most commonly reported nationally include:
- Blacklegged tick — Ixodes scapularis
- Lone star tick — Amblyomma americanum
- American dog tick — Dermacentor variabilis
- Western blacklegged tick — Ixodes pacificus
- Rocky Mountain wood tick — Dermacentor andersoni
Other human-biting species include the groundhog tick, Pacific Coast tick, brown dog tick, Gulf Coast tick, Asian longhorned tick, and several soft tick species.
Remember: The presence of a particular tick species in an area does not automatically mean that every pathogen associated with that species is being transmitted in that location. Local disease risk depends on many factors, including pathogen prevalence, tick populations, geography, and exposure
Tick Life Stages Matter
A tick can look very different depending on its life stage and whether it has recently fed.
Most hard ticks progress through four life stages:
Egg → Larva → Nymph → Adult
Larval ticks have six legs, while nymphs and adult ticks have eight legs.
After feeding, a tick’s body can become significantly enlarged and may change in color and shape, making identification more difficult.
For this reason, compare more than one characteristic when attempting to identify a tick.
What to Do After a Tick Bite
If you find an attached tick:
- Remove it as soon as possible.
- Use clean, fine-tipped tweezers and grasp the tick as close to the skin as possible.
- Pull upward using steady, even pressure.
- Do not twist, jerk, burn, smother, or coat the attached tick with substances in an attempt to make it detach.
- Clean the bite area and your hands after removal.
- Check the rest of your body for additional ticks.
You may want to record when and where the possible tick exposure occurred, particularly if symptoms later develop.
CDC generally does not recommend using commercial testing of a removed tick to make treatment decisions. A positive tick test does not mean that transmission occurred, while a negative result cannot rule out other unrecognized tick exposures.
When to Contact a Healthcare Provider
Contact a qualified healthcare provider if you develop a fever, rash, unusual fatigue, headache, body aches, muscle or joint pain, nausea, vomiting, neurologic symptoms, or other concerning symptoms following a known or possible tick exposure.
Symptoms of different tick-associated illnesses can overlap and may develop within days or weeks of exposure.
Tell your healthcare provider:
- That a tick bite or possible tick exposure occurred
- Approximately when the exposure occurred
- Where you may have encountered the tick
You may not always know that you were bitten. Some ticks—particularly nymphs and soft ticks—can be very small or feed without being noticed
Identification Note
Tick identification can sometimes be difficult. Ticks of the same species can look different depending on life stage, sex, feeding status, and image angle, while unrelated species may have similar coloration or markings.
The photographs and descriptions in this guide are intended to provide general educational identification information.
Identifying a tick species does not determine whether the tick was infected with a disease-causing organism or whether disease transmission occurred.
Ticks That Commonly Bite Humans
Continue Learning About Ticks
Explore additional Tick Education & Resources:
How to Safely Remove Ticks
Tick Identification Guide
Tick Check Yourself!
Tick Prevention Tips
Quick Tick Guide
The Secret of How Ticks Attach
Frequently Asked Questions
Learn About Tick-Associated Diseases & Conditions
Explore our educational resources on:
- Lyme Disease
- Alpha-Gal Syndrome
- Anaplasmosis
- Babesiosis
- Bourbon Virus Disease
- Borrelia mayonii
- Ehrlichiosis
- Colorado Tick Fever
- Hard Tick Relapsing Fever
- Soft Tick Relapsing Fever
- Powassan Virus Disease
- Heartland Virus Disease
- Pacific Coast Tick Fever
- Rickettsia lanei Rickettsiosis
- Rickettsia parkeri Rickettsiosis
- Rocky Mountain Spotted Fever
- Southern Tick-Associated Rash Illness
- Tularemia
Sources
Information for this guide was reviewed using authoritative public-health resources, including:
- Centers for Disease Control and Prevention (CDC) — Ticks
- CDC — Where Ticks Live
- CDC — What to Do After a Tick Bite
- CDC — Tickborne Diseases of the United States
- CDC — Powassan Virus
- CDC — Alpha-Gal Syndrome
- CDC — Southern Tick-Associated Rash Illness
- CDC — Tick and Louse-borne Relapsing Fevers
- CDC — Other Spotted Fever Rickettsioses
- U.S. Department of Agriculture (USDA) — Asian Longhorned Tick resources
Educational Disclaimer
This information is provided for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
If you develop a fever, rash, unusual fatigue, headache, body aches, nausea, vomiting, neurologic symptoms, or other concerning symptoms following a known or possible tick exposure, contact a qualified healthcare provider and mention the potential tick exposure.
