Dermacentor variabilis, commonly known as the American dog tick, is found in grassy and wooded areas across North America. It is a vector for diseases such as Rocky Mountain spotted fever. Notably, it has a reddish-brown body with silvery-gray patterns on its back.

Dermacentor variabilis, commonly known as the American dog tick, is native to North America. Its geographical distribution primarily includes the eastern United States, extending from the Atlantic coast to the eastern edge of the Rocky Mountains. It is also found in parts of Canada, including southern regions of Manitoba, Ontario, and Quebec. The range further extends into parts of Mexico, primarily in the northeastern regions.

The American dog tick typically inhabits areas with a relatively warm climate and moderate to high humidity. It thrives in environments with tall grasses, wooded areas, and open fields, which provide ideal conditions for questing and locating hosts. These ticks are often found in transitional zones between forested and open areas, which are frequented by their primary hosts, such as small mammals and larger hosts like dogs and deer.

Dermacentor variabilis plays a significant role as both a parasite and a vector in its ecosystem. As an ectoparasite, it feeds on the blood of various mammalian hosts, including humans, dogs, and wildlife, for sustenance and reproduction. It is also a vector for several pathogens, most notably the bacterium Rickettsia rickettsii, which causes Rocky Mountain spotted fever. The tick's life cycle and behavior are closely linked to its ecological niche, relying on host availability and environmental conditions for survival and reproduction.