Gulf Coast tick (Amblyomma maculatum)
The Gulf Coast tick (Amblyomma maculatum) is a medium-to-large hard tick with a showy pattern. It was long tied to the Gulf of Mexico and southern Atlantic coasts. Now its range is spreading well inland and up the East Coast. Adults are dark brown with striking silvery-white markings on the shield (scutum) and long, rectangular mouthparts. In the United States, it is the main carrier of Rickettsia parkeri rickettsiosis. This is a spotted fever illness that is generally milder than Rocky Mountain spotted fever. It is not a main carrier of Rocky Mountain spotted fever. It also does not spread Lyme disease, ehrlichiosis, anaplasmosis, or the other common US tick-borne diseases. This page is for learning and is not medical advice.
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How to identify it
- Adult female: dark reddish-brown body with a small, dark shield (scutum) behind the head. The shield has showy silvery-white markings: one stripe down the middle plus two broken stripes on the sides. It is not a single round dot.
- Adult male: the patterned shield covers the whole back. It is dark brown, laced with a connected network of silvery-white lines.
- Long, rectangular mouthparts (an Amblyomma trait). They are much longer than the short, stubby, pyramid-shaped mouthparts of the American dog tick.
- Eyes along the sides of the shield, and festoons (small ridges) along the rear edge of the body. Overall it is a large tick, clearly bigger than a blacklegged (deer) tick.
- Young stages (larvae and nymphs) are small and mostly unmarked. The bold silvery pattern is an adult feature.
Size by life stage
Larvae ('seed ticks') are about 0.5 mm with six legs. Unfed nymphs are about 1.3 x 0.75 mm. Unfed adults are about 6 mm (~1/4 inch), clearly larger than a deer tick. A fully fed female can swell to roughly 1/2 inch (10+ mm) or more.
Where it lives and when
Long known as a coastal tick of the Gulf of Mexico and southern Atlantic shores. Its home range is a band roughly 100–150 miles inland, from Texas east across the Gulf states to Florida and up to South Carolina. Established inland groups now reach Oklahoma, Kansas, Arkansas, Missouri, Kentucky, Illinois, and Indiana. Records also show it has settled up the Atlantic coast through Maryland, Delaware, New Jersey, and New York, and into Connecticut. In New York this includes restored grasslands on Staten Island. This is the Gulf Coast tick's own range, along the coast and into the middle of the country. It is separate from the Lone Star tick's range and should not be treated as the same.
Season
Adults, the stage that bites people, are most active in the warm months, broadly spring through early fall. Timing shifts by region. Activity is reported almost all year along the warm Gulf coast. Inland groups (for example in Oklahoma and Kansas) are active roughly February–October. In northern Florida they are active roughly February–September.
Where it waits
- Open grassland and prairie, coastal uplands, and edges where fields meet forest
- Overgrown fields, pastures, and reclaimed grassy lots. This includes city grasslands in northeastern cities it has newly reached
- Drier, sunnier grassy sites. It is less tied to dense, shady woods than the Lone Star tick
Diseases it can carry
Rickettsia parkeri rickettsiosis, a spotted fever that is usually milder than Rocky Mountain spotted fever. It often starts with a dark scab where the tick bit. This guide has no page for it yet; the questions below cover it.
Look-alikes
It is most easily confused with its close relative, the Lone Star tick. Both are Amblyomma ticks with long mouthparts. But a Gulf Coast female has showy silvery stripes spread across the shield, not the Lone Star female's single round white 'lone star' dot. It is also mistaken for the American dog tick, which is patterned too. Tell them apart by the mouthparts: the Gulf Coast tick's are long and rectangular, while the dog tick's are short and pyramid-shaped. The Gulf Coast tick's shield is also larger, with more pattern. Young larvae and nymphs are hard to tell apart by eye, so when in doubt, have the tick identified.
Compare all tick speciesCommon questions
What disease does the Gulf Coast tick spread?
Mainly Rickettsia parkeri rickettsiosis. In the United States, it is the main carrier of this spotted fever illness. It often starts with a dark scab at the bite site (an eschar) a few days to about a week later. Then come fever, headache, muscle aches, and rash. It is generally milder than Rocky Mountain spotted fever and responds to prompt doxycycline. See a doctor to get checked. This page is for learning, not medical advice.
Does the Gulf Coast tick cause Rocky Mountain spotted fever?
No. Rocky Mountain spotted fever is caused by Rickettsia rickettsii. It is spread mainly by the American dog tick, Rocky Mountain wood tick, and brown dog tick. The Gulf Coast tick spreads a different, usually milder spotted fever caused by Rickettsia parkeri.
How do I tell a Gulf Coast tick from a Lone Star tick?
Check the shield. Both are Amblyomma ticks with long mouthparts. A Gulf Coast female has showy silvery-white stripes across the back. A Lone Star female has a single round white dot in the center. Gulf Coast ticks also tend to be a little larger.
Where are Gulf Coast ticks found?
Along the Gulf and southern Atlantic coasts, and spreading. Their traditional range runs along the Gulf of Mexico and southern Atlantic coasts from Texas to South Carolina. Established groups now reach inland to states such as Oklahoma, Kansas, Arkansas, and Missouri. They also reach up the East Coast as far as Connecticut.
Sources
- 1.
- 2.TickEncounter Resource Center (opens in a new tab) · University of Rhode Island
Tick identification, prevention, and reporting resources.
- 3.Where Ticks Live (opens in a new tab) · CDC
The Lone Star tick is widely distributed in the Northeast, South, and Midwest U.S.
- 4.
Educational information only, not medical advice. If you were bitten, use the tick bite tool and contact a licensed clinician if symptoms develop. Read our sources and disclaimer.