American dog tick
Dermacentor variabilis
Personal protection and habitat management at the yard edge address exposure directly.
- Scientific name
- Dermacentor variabilis
- Size
- 3–5 mm
- Group
- Ticks
- Identification confidence
- Identifiable with care
No licensed photograph yet
We have not yet licensed a photograph for this species. The written description above is complete and is what the identification depends on — it is not a caption for a missing picture.
How to recognise it
These are the features that identify a american dog tick. Each one is described in words so the identification works without the diagram.
- The shield behind the head carries conspicuous white or silvery mottled ornamentation, unlike the blacklegged tick's solid dark shield.
- Adults are larger and more rounded at 3 to 5 mm unfed, and distinctly brown.
- The mouthparts are short compared with the blacklegged tick.
What it leaves behind
- Ticks found after time in grassy fields, along trails, and in scrubby edge habitat rather than deep woodland.
- Peak activity in spring and early summer.
Why an infestation persists
A vector of Rocky Mountain spotted fever and tularemia, though not of Lyme disease. Correct species identification therefore changes which illnesses are plausible after a bite, which is why it matters clinically.
Where it occurs
East of the Rocky Mountains and in limited parts of the Pacific coast.
Where to look for it
- On the body and on dogs after time in grassy fields, meadows, and along trail margins.
- [object Object]
- Along the sides of paths and trails, where this species waits on grass stems.
- Around the ears, neck, and between the toes on a dog.
When you see it, and why
Adults are active from spring into midsummer, peaking earlier than the autumn blacklegged tick peak. Because the preferred habitat is open grassy and edge ground rather than deep woodland, exposure tends to come from field margins, verges, and trailsides rather than from forest interiors.
What getting the identification wrong costs you
The white mottled ornamentation on the shield separates this from the blacklegged tick, and the practical value of the distinction is clinical: this species transmits Rocky Mountain spotted fever and tularemia but not Lyme disease. Telling a clinician which tick it was narrows what they are looking for, which is why keeping the specimen is worth the small effort.
What a professional actually does
Area spraying is not what decides your exposure, and it is worth knowing that before buying it. Prompt and thorough tick checks after time outdoors do more than any treatment, and on a property the useful work is landscaping: keeping grass mown, clearing brush along paths and boundaries, and widening the margin between a trail and tall grass. That is a groundskeeping cost, not a pest control one.
What prevents it
- Stay to trail centres and avoid brushing through tall grass at field edges.
- Perform prompt tick checks on people and pets.
- Keep grass mown and clear brush along paths and property edges.
Commonly confused with
Blacklegged tick Ixodes scapularis
Adult females have a solid dark reddish-orange abdomen with a distinct solid black shield behind the head, and no white markings or ornamentation.
Brown dog tick Rhipicephalus sanguineus
Uniform reddish-brown with no white ornamentation on the shield, separating it from the American dog tick.
Lone star tick Amblyomma americanum
Adult females carry a single conspicuous white or cream spot in the centre of the back — the "lone star" — which is unmistakable and needs no magnification.
Sources
Every claim on this page traces to one of these.
- US Environmental Protection Agency Tier 1. Pesticides.
- National Pesticide Information Center Tier 1. National Pesticide Information Center.
- Cooperative Extension System Tier 2. University extension entomology resources.