Dermacentor variabilis, commonly known as the American dog tick, is a species of tick found primarily in the eastern and central United States. It is characterized by a flat, oval body and a distinctive pattern of light and dark markings. Adult ticks typically feed on the blood of mammals, particularly dogs, but can also bite humans. This tick is known to transmit several diseases, including Rocky Mountain spotted fever and Tularemia. They are most active in the spring and early summer, making it important for pet owners and outdoor enthusiasts to take precautions against tick bites during these seasons.