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How to identify it
- Brown body; adults have a complex whitish pattern on the shield and short mouthparts.[2]
- On females the oval shield covers only the front of the back; nymphs and larvae are brown or tan.[2]
- Adult American dog ticks are much larger than blacklegged ticks and a little larger than lone star ticks.[8]
- Males feed briefly and never swell up; females take a week or more to engorge fully.[7]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Blacklegged tick | Much smaller, with a plain black shield, black legs and long mouthparts and no whitish pattern.[2][8] |
| Rocky Mountain wood tick | A western Dermacentor tick; CDC lists it separately, with Colorado tick fever among the diseases it spreads. West of the Rockies, ticks long called American dog ticks are now described as a separate species, Dermacentor similis.[1][9] |
Where it lives
Widely distributed east of the Rocky Mountains, with limited areas to the west; found along forest and trail edges and in fields and meadows. A related species, D. similis, occurs west of the Rockies.[1][2]
Biology and life cycle
It is a three-host tick: larvae and nymphs feed mainly on small mammals such as mice, voles and chipmunks, and adults prefer medium-sized hosts such as raccoons, skunks, cats and dogs.[7]
Adults wait in tall grass and low brush. Nymphs and larvae rarely attach to people or pets.[7][2]
After feeding, a female drops into the leaf litter and can lay over 4,000 eggs before she dies.[7]
Kentucky says adults can survive up to two years without feeding; URI TickEncounter says that is true at any life stage when no host is found.[2][7]
Damage and signs
Health risk
CDC lists tularemia and Rocky Mountain spotted fever as diseases this tick can transmit, and says RMSF can be deadly if not treated early with doxycycline. Infection appears uncommon in the ticks themselves: Minnesota's health department says American dog ticks rarely spread disease there, and an Army lab found the RMSF bacterium in only one of 5,286 American dog ticks removed from people between 1997 and 2009.[1][5][6][8][10]
Control
Prevention
Use an EPA-registered repellent (DEET, picaridin, IR3535, oil of lemon eucalyptus, PMD or 2-undecanone) and treat clothing and gear with 0.5% permethrin; walk in the center of trails.[4]
Make the yard less tick-friendly: remove leaf litter, clear tall grass and brush, mow often, and put a 3-foot strip of wood chips or gravel between lawn and woods.[4]
Sanitation
After being outdoors, tumble dry clothes on high heat for 10 minutes, check gear and pets, shower within two hours, and do a full-body tick check.[4]
Traps and physical control
Remove an attached tick right away with fine-tipped tweezers, grasping close to the skin and pulling straight out with steady, even pressure; don't twist or jerk, and don't use petroleum jelly, heat or nail polish. See a doctor if a rash or fever develops within several weeks.[3]
Pesticides
Yard pesticide applications can reduce ticks, but you shouldn't rely on spraying alone to prevent infection.[4]
Diseases and how often ticks carry them
Rocky Mountain spotted fever usually starts with fever and headache, and a rash commonly follows 2 to 4 days after the fever begins. CDC names the American dog tick, the brown dog tick and the Rocky Mountain wood tick as U.S. carriers.[5]
Tularemia reaches people through tick and deer fly bites, contact with infected animals such as rabbits and rodents, and other routes. In 2017 the Minnesota Department of Health found tularemia bacteria in 34 percent of pooled American dog tick samples, an estimated minimum infection rate of 3.6 percent.[6][11]
CDC says more research is needed to understand the role of Dermacentor variabilis and the western species, D. similis, in disease transmission.[1]
Where sources disagree
Season: Kentucky says adults and nymphs are active March through September; URI TickEncounter says adults are active April to early August in most regions, and CDC puts the highest bite risk in spring and summer.[2][7][1]
Common questions
- When are American dog ticks most likely to bite?
- Spring and summer, mostly by adult females.[1]
- Does the American dog tick carry Lyme disease?
- CDC lists tularemia and Rocky Mountain spotted fever for this tick; Lyme disease is spread by blacklegged ticks.[1]
- Are American dog ticks found west of the Rockies?
- In limited areas. Western populations are now described as a separate species, Dermacentor similis.[1][9]
Sources
- Centers for Disease Control and Prevention, “Where Ticks Live.” www.cdc.gov/ticks/about/where-ticks-live.html (accessed 2026-11-11)
- University of Kentucky Entomology, “ENTFACT-618: Ticks and Disease in Kentucky.” entomology.mgcafe.uky.edu/ef618 (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “What to Do After a Tick Bite.” www.cdc.gov/ticks/after-a-tick-bite/index.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Preventing Tick Bites.” www.cdc.gov/ticks/prevention/index.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “About Rocky Mountain Spotted Fever.” www.cdc.gov/rocky-mountain-spotted-fever/about/index.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “About Tularemia (updated August 27, 2026).” www.cdc.gov/tularemia/about/index.html (accessed 2026-11-11)
- University of Rhode Island TickEncounter, “American Dog Tick.” web.uri.edu/tickencounter/species/american-dog-tick-2/ (accessed 2026-11-11)
- Minnesota Department of Health, “Ticks (updated June 30, 2025).” www.health.state.mn.us/diseases/tickborne/ticks.html (accessed 2026-11-11)
- Journal of Medical Entomology, via PubMed, “Lado, Glon and Klompen (2021), Integrative taxonomy of Dermacentor variabilis with description of a new species, Dermacentor similis.” pubmed.ncbi.nlm.nih.gov/34378782/ (accessed 2026-11-11)
- Vector-Borne and Zoonotic Diseases, via PubMed, “Stromdahl et al. (2011), Infrequency of Rickettsia rickettsii in Dermacentor variabilis removed from humans.” pubmed.ncbi.nlm.nih.gov/21142953/ (accessed 2026-11-11)
- Vector-Borne and Zoonotic Diseases, via PubMed, “Whitten et al. (2019), Prevalence of Francisella tularensis in Dermacentor variabilis ticks, Minnesota, 2017.” pubmed.ncbi.nlm.nih.gov/30758273/ (accessed 2026-11-11)
- iNaturalist, “Dermacentor variabilis taxon page (order and family).” www.inaturalist.org/taxa/52155 (accessed 2026-11-11)