Ixodes scapularis

Ixodes scapularis is commonly known as the deer tick or black-legged tick (although some people reserve the latter term for Ixodes pacificus, which is found on the west coast of the USA), and in some parts of the US as the bear tick. It is a hard-bodied tick (family Ixodidae) of the eastern and northern Midwestern United States and southeastern Canada. It is a vector for several diseases of animals, including humans (Lyme disease, babesiosis, anaplasmosis, Powassan virus disease, etc.) and is known as the deer tick owing to its habit of parasitizing the white-tailed deer. It is also known to parasitize mice, lizards, migratory birds, etc. especially while the tick is in the larval or nymphal stage. The image shown here—and in fact, most images of Ixodes scapularis that are commonly available—show an adult that is unengorged, that is, an adult that has not had a blood meal. This is natural, since ticks are generally removed immediately upon discovery to minimize the chance of disease. However, the abdomen that holds blood is much larger when engorged; therefore, an engorged specimen of I. scapularis (see photo below) could easily be mistaken for an entirely different tick.