American Dog Tick Identification & Control

Quick Identification

• Size: Unfed adults about 3/16 inch; engorged females can reach ½ inch (size of a small grape)
• Color: Reddish-brown; females have a large silver-white spot behind the head; males have fine silver lines on back
• Key Features: Larger and more robust than deer ticks; distinctive white markings; oval body
• Active Season: April through June (adults); inactive by September
• Risk Level: Moderate — primary carrier of Rocky Mountain spotted fever in Illinois; also transmits tularemia

The Most Common Tick in Illinois

The American dog tick is the tick most frequently encountered by Illinois residents. The Illinois Department of Public Health reports that it accounts for the majority of ticks submitted for identification. Adults are most active from April through June, feeding on medium to large mammals including dogs and humans. By September, adult activity essentially stops.

The American dog tick is the primary carrier of Rocky Mountain spotted fever (RMSF) in our area — a serious bacterial infection with symptoms including sudden fever, severe headache, and a distinctive rash that starts on the limbs. RMSF can be severe if not treated promptly with antibiotics. This tick also transmits tularemia and may be associated with ehrlichiosis.

Despite being called the “dog tick,” these ticks readily bite humans. They’re most often encountered in grassy fields, along trails, and in low vegetation near paths — anywhere people and dogs walk through tall grass. If you or your pets spend time outdoors in Will County during spring and early summer, tick checks afterward are essential. For professional tick treatment of your property, contact Sanctuary Pest Control at 815-993-3472.