The American Dog Tick in Massachusetts
The American dog tick (Dermacentor variabilis), or wood tick, is common statewide in grassy areas and is the tick people most often find on a dog, or on themselves, in summer. Reassuringly, it does not carry Lyme disease or alpha-gal.
How to tell it apart
Three ticks bite people in Massachusetts, and only one carries Lyme.
American dog tick
Larger, with an ornate mottled white-and-brown back. Carries RMSF and tularemia (both rare).
Deer tick
Smaller, a plain dark shield, no markings. The one that carries Lyme.
Lone star tick
A single white dot on the female. Causes alpha-gal syndrome.
Diseases it can carry
Rocky Mountain spotted fever
A bacterial infection (Rickettsia rickettsii) causing fever, headache, and a rash that often begins on the wrists and ankles. It is rare in New England but can be life-threatening if untreated, so early doxycycline matters. Despite the name, most US cases are in the Southeast.
Tularemia
A bacterial infection (Francisella tularensis), sometimes called “rabbit fever,” that can also spread other ways. Massachusetts is best known for outbreaks on Martha’s Vineyard. It is uncommon and treatable with antibiotics.
It does not transmit Lyme disease, babesiosis, anaplasmosis, or alpha-gal syndrome.
When it's active
Adults are out from spring through summer, peaking roughly May through July. Only the adults commonly bite people; younger stages feed on small mammals like mice.
How to protect yourself
The same steps that work for all ticks: EPA-registered repellent, permethrin-treated clothing, staying to the center of trails, and checking yourself and your dog after grassy areas. Not medical advice.
Frequently asked questions
- Does the American dog tick cause Lyme disease?
- No. The dog tick does not transmit Lyme disease, babesiosis, anaplasmosis, or alpha-gal syndrome. It can carry Rocky Mountain spotted fever and tularemia, both uncommon in Massachusetts. Lyme is spread by the deer tick.
- How do I tell a dog tick from a deer tick?
- The American dog tick is larger and has an ornate mottled white or cream pattern on its back, while the deer tick is smaller with a plain dark shield and no markings. The lone star tick has a single white dot. Only the deer tick carries Lyme.
- Where do you find American dog ticks?
- In grassy and brushy areas, along trails, roadsides, and in yards, across all of Massachusetts. They are the tick people most often find crawling on a dog or on themselves in late spring and summer.
- When are American dog ticks active?
- Adults are active from spring through summer, peaking roughly May through July. Only the adults commonly bite people; the younger stages feed mostly on small mammals.