Gulf Coast Tick: How to Identify It & What It Spreads

Quick answer

The Gulf Coast tick (Amblyomma maculatum) is a reddish-brown hard tick with silvery-white markings and long mouthparts. It lives mainly in the southeastern U.S., in open grassy areas, and has spread into other regions. CDC links it to Rickettsia parkeri rickettsiosis, a milder form of spotted fever. It does not spread Lyme disease.

What the guidelines say

CDC says the Gulf Coast tick is found primarily in the southeastern United States, with focal populations in the Northeast, Midwest and Southwest.
CDC lists one human disease for this tick: Rickettsia parkeri rickettsiosis, a form of spotted fever. CDC says adult ticks have been associated with spreading it to people.
CDC names only blacklegged ticks as spreaders of Lyme disease in the U.S. The Gulf Coast tick is not one of them.

What a Gulf Coast tick looks like

The Gulf Coast tick is a medium-sized hard tick with silvery-white markings on a reddish-brown body. Extension guides describe each stage:

Adults: about 3 to 7 mm long (roughly 1/8 to 1/4 inch), and can swell to about 1/2 inch when fully fed. Fed adults can look gray.
Females: reddish-brown with a light, ornate shield covering about half the back, just behind the head.
Males: the ornate pattern covers the whole back.
Nymphs: about the size of a poppy seed, eight legs.
Larvae: under 1 mm (pinhead size), six legs.

Easy to confuse with: the American dog tick, which also has light markings. Extension guides say the Gulf Coast tick has longer, narrower mouthparts, while the American dog tick’s are short and stout. Compare it with the lone star tick and others in our types of ticks guide.

Where it lives in the US

CDC’s map shows the Gulf Coast tick mainly in the Southeast, with scattered populations farther north and west. Historically it stayed close to the coasts of the Gulf of Mexico and the southern Atlantic. Extension researchers say it has spread widely since about 2000, possibly carried by migrating grassland birds. Established populations are now reported in states such as Oklahoma, Kansas, Missouri, Arkansas, Illinois, Indiana, Kentucky, Tennessee, Virginia, Maryland, Pennsylvania, Delaware and New Jersey, and in parts of Ohio.

Habitat: unlike forest-loving ticks, the Gulf Coast tick prefers open ground: grassland prairies, shrubby fields, and recently disturbed land with tall grass and little tree cover.

Hosts: young ticks feed on small mammals and ground-dwelling birds. Adults feed on larger animals such as deer, cattle, horses, dogs, and sometimes people.

When it is active

Ohio State University Extension says adults are most often found in the warm summer months, while larvae and nymphs are usually active in spring and fall. In a CDC report on cases in Georgia, people got sick between June and October.

Diseases it can spread

The main human disease linked to this tick is Rickettsia parkeri rickettsiosis, one of the spotted fever rickettsioses. The bacterium is closely related to the one that causes Rocky Mountain spotted fever, but CDC’s provider manual says R. parkeri illness is generally less severe.

A typical sign is an eschar: a dark, scabbed or ulcer-like sore at the bite site. CDC’s manual says an eschar is almost always present with R. parkeri, which is unusual for Rocky Mountain spotted fever. A few days after the eschar appears, people may get:

fever
headache
muscle aches
a sparse rash on the trunk, arms or legs

CDC’s manual gives an incubation period of about 2 to 10 days. It also notes that standard spotted fever blood tests cannot tell R. parkeri apart from other spotted fever bacteria. The first confirmed human case was reported in 2004, and CDC says the true number of cases is unknown.

Other effects: extension sources say this tick can cause tick paralysis, which is uncommon and usually improves once the tick is removed. In dogs, it spreads American canine hepatozoonosis when a dog swallows an infected tick while grooming.

When to see a provider

If you get a dark scab or sore where a tick was attached, followed by fever, headache, aches or a rash, see a health care provider and mention the tick bite and where you were. CDC says doxycycline is the recommended treatment for R. parkeri rickettsiosis, and your provider decides whether you need it.

Gulf Coast tick bites

Adult Gulf Coast ticks are the stage most linked to illness in people, according to CDC. Ticks are easy to miss, so do a full-body check after time in tall grass or fields. If you find a tick attached, remove it promptly. Our tick bite guide covers removal and the symptoms to watch for in the weeks after.

What patients tell us

We are collecting real experiences about Gulf Coast tick bites and spotted fever from people who have lived it, shared with their permission. As stories come in, they will appear here, clearly marked as personal experience rather than medical advice.

Share your experience

Prevention

The same steps that protect against other ticks work here. CDC’s report on R. parkeri cases recommends:

Avoiding tick habitat, such as tall grass and brush, when you can.
Using an EPA-registered insect repellent.
Checking yourself, your children and your pets after time outdoors.
Removing attached or crawling ticks promptly.

For the full prevention plan, see Lyme disease prevention and Step 1 of How to beat Lyme: Prevent it. Wondering which ticks you really need to worry about for Lyme? See ticks that carry Lyme disease.

At a glance

Scientific name	Amblyomma maculatum
Adult size	About 3 to 7 mm; up to about 1/2 inch when fully fed
Color and markings	Reddish-brown with silvery-white ornate markings; long mouthparts
Where in the US	Mainly the Southeast; spreading into the Midwest, Mid-Atlantic and Northeast
Habitat	Open grasslands, shrubby fields, few trees
Most active	Adults in summer; larvae and nymphs spring and fall
Disease to people (CDC)	Rickettsia parkeri rickettsiosis (a spotted fever)
Spreads Lyme?	No

Frequently asked questions

Does the Gulf Coast tick carry Lyme disease?

No. CDC names only blacklegged ticks as spreaders of Lyme disease in the U.S. The Gulf Coast tick is linked to Rickettsia parkeri rickettsiosis, a type of spotted fever.

How can I tell a Gulf Coast tick from an American dog tick?

Both have light markings. Extension guides say the Gulf Coast tick has silvery-white markings and longer, narrower mouthparts, while the American dog tick has short, stout ones. A magnifying glass helps, and an extension office can confirm.

What does a Gulf Coast tick bite look like?

In a CDC report from Georgia, the first signs were redness and swelling at the bite site. With R. parkeri infection, CDC describes an eschar: a dark, scabbed or ulcer-like sore at the bite site, often followed days later by fever, headache, aches or a sparse rash.

Gulf Coast Tick: Identification, Range and Disease Risk