Tick basics awaiting entomology signoff
American dog tick
Dermacentor variabilis
Look for the larger brown tick with a white or silvery patterned shield rather than a plain dark shield.
I
approx. 4-6 mm unfed
Size by life stage
- Adult female
- approx. 4-6 mm unfed source caveated editorial
- Adult male
- approx. 3-5 mm unfed source caveated editorial
- Nymph
- approx. 1-2 mm; nymphs are less often the reader-facing ID focus than ornate adults source caveated editorial
- Larva
- approx. 0.5-1 mm; larvae have 6 legs source caveated editorial
How to tell it apart
- Scutum: Ornate white/silvery scutum markings; adult male pattern can cover much of the back.
- Color (unfed): Brown to reddish-brown body with pale ornate markings on the scutum.
- Color (engorged): Engorged females can become grayish or olive-gray behind the ornate scutum.
Where it lives
Region: Widely established east of the Rocky Mountains, with some western coastal distribution depending on source.
Habitat preference: Grassy fields, brushy edges, trails, roadsides, and dog/wildlife travel corridors.
Hosts: dogs, humans, medium-sized mammals, wildlife
Where this species shows up in our state guides
Primary species in: Arkansas, California, Connecticut, Florida, Georgia, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, Tennessee, Texas, Vermont, Virginia, Washington, Wisconsin
Disease associations
- can transmit Rocky Mountain spotted fever
- associated with tularemia
Look-alikes
- blacklegged deer tick
- brown dog tick
- gulf coast tick
- ornate Dermacentor species
Sources
- CDC Where Ticks Live
- PA DEP American Dog Tick
- PA Tick Research Lab American Dog Tick
- CDC Tick Life Cycles