American Dog Tick

📐 FIELD GUIDE ILLUSTRATION

Original illustration by PestControlBasics.com. Use the labeled features above to confirm your identification.

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PestControlBasics Editorial Team

Reviewed by Derek Giordano · Updated 2026

🔍 Identification

Adults: 5-6mm unfed, 15mm engorged; brown with distinctive white/cream markings on the shield (scutum); females have whitish-patterned scutum, males have white markings throughout. Found in grassy areas, along trails, and in transitional zones between woods and open areas — different microhabitat from deer ticks which prefer leaf litter. Range: east of the Rockies and along the Pacific Coast.

🧬 Biology & Behavior

Rocky Mountain Spotted Fever (RMSF) caused by Rickettsia rickettsii — transmitted after 4-6 hours of attachment. Symptoms: fever, headache, and rash (petechial rash appears on wrists and ankles, spreads inward — appears 3-5 days after fever). Untreated mortality: 20-25%. With prompt doxycycline treatment: near-zero mortality. The name is misleading: 60%+ of US RMSF cases occur in North Carolina, Tennessee, Arkansas, Oklahoma, and Missouri.

⚠️ Damage & Health Risk

Rocky Mountain Spotted Fever — potentially fatal if not treated promptly; tick paralysis (rare — ascending paralysis that resolves after tick removal); tularemia transmission.

🔧 DIY Treatment

Daily tick checks in grassy areas; permethrin on clothing; bifenthrin lawn edge treatment in May and September. RMSF early treatment: doxycycline should be started empirically when RMSF is clinically suspected — do not wait for laboratory confirmation. Early treatment is the difference between full recovery and life-threatening illness.

👷 When to Call a Pro

Tick population management combined with awareness and prompt medical treatment is the complete prevention strategy.

❓ FAQ

How is RMSF different from Lyme disease?

RMSF requires much shorter attachment time (4-6 hours vs 36-48 hours for Lyme). RMSF can be fatal without prompt treatment; Lyme is rarely fatal but causes chronic illness if untreated. RMSF causes a petechial rash on wrists/ankles; Lyme causes the bull's-eye rash at the bite site. RMSF is caused by bacteria in the Rickettsia genus and requires doxycycline treatment.

What does RMSF rash look like?

The classic RMSF rash appears as small red spots on the wrists and ankles, spreading toward the trunk — appearing 3-5 days after fever onset. It may become petechial (small purple/red non-blanching spots). Importantly, 10-15% of RMSF cases never develop a rash. Fever + severe headache after a tick bite in the appropriate geographic area warrants immediate medical evaluation regardless of rash.

🕷️ American Dog Tick