Of the many different tick species found throughout the world, only a select few bite and transmit disease to people. Of the ticks that bite people, different species of ticks transmit different diseases. These maps show the general distribution of human-biting ticks in the contiguous United States. Populations of ticks may be found outside shaded areas. Naturally occurring populations of the ticks described below do not occur in Alaska; however, the brown dog tick occurs in Hawaii.

Note that adult ticks are the easiest to identify and male and female ticks of the same species may look different. Nymphal and larval ticks are very small and may be hard to identify.