Tick basics awaiting entomology signoff

Lone star tick

Amblyomma americanum

On an adult female, the single pale dot on the back is the fastest visual clue.

I
approx. 4-6 mm unfed
Macro photo of an unfed adult female lone star tick showing the single pale dot on the back and millimeter scale

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; small nymphs may not show the adult female dot source caveated editorial
Larva
approx. 0.5-1 mm; larvae have 6 legs source caveated editorial

How to tell it apart

  • Scutum: Adult female has a single pale/white dot; adult male is more diffusely patterned and lacks the single-dot cue.
  • Color (unfed): Reddish-brown to brown; the adult female's single pale dot is the reader-facing cue.
  • Color (engorged): Engorged body can become larger and gray/tan; the dot may be harder to use after feeding.

Where it lives

Region: Established across much of the south-central, southeastern, mid-Atlantic, and parts of the eastern U.S.

Habitat preference: Wooded edges, brush, tall grass, wildlife corridors, and suburban/rural edge habitats.

Hosts: humans, dogs, deer, wildlife, birds

Emerging in: upper Midwest and northeastern edge states where CDC range mapping, state health surveillance, and university extension sources document expansion or local establishment

Disease associations

Listed associations come from public-health and entomology sources. This is orientation, not diagnosis. If you develop symptoms after a tick bite, contact a clinician.

  • associated with ehrlichiosis
  • associated with STARI discussion
  • associated with alpha-gal syndrome context

Look-alikes

Sources

  • CDC Where Ticks Live
  • CDC Lone Star Tick Range Map PDF
  • PA DEP Lone Star Tick
  • Texas A&M TickApp Lone Star Tick
  • UMaine Lone Star Tick

See the global sources index for every reference cited on the site.