Ticks, of which there are more than 500 species worldwide, are parasitic arthropods closely related to mites. They are not insects. Most ticks feed on the blood of warm-blooded mammals, but some species also feed on birds, reptiles, and even amphibians. Fish are apparently the only vertebrates not plagued by these tiny bloodsuckers. Many species of ticks can transmit diseases from an infected host to other, uninfected hosts. Some of the more frequently transmitted organisms include parasitic worms, viruses, bacteria, spirochetes, and rickettsia’s. The most common of these to Pennsylvania are spirochetes, which cause Lyme disease, and rickettsia’s, which cause Rocky Mountain spotted fever. Currently, more than 25 species of ticks have been identified in Pennsylvania. Of these, 4 species account for nearly all tick problems in Pennsylvania.

(1) The American dog tick

(2) The black- legged tick

(3) The groundhog tick

(4) The lone star tick

American Dog Tick is found in the eastern two-thirds of the United States, from Nova Scotia to the Gulf Coast. Occurring in most counties, it is the most commonly encountered tick in Pennsylvania.

The immature stages are frequently found on small rodents such as meadow mice. The adults are frequently found on dogs (hence the name) and can be recognized by the distinctive white markings on their backs. The American dog tick may become greatly engorged, achieving the size of a grape. In addition to humans, other hosts are cats, cattle, donkeys, hogs, horses, mules, sheep, coyotes, deer, foxes, wolves, wildcats, badgers, opossums, rabbits, raccoons, rats, skunks, squirrels, weasels, and groundhogs.

American dog ticks are the major carrier of Rocky Mountain spotted fever, which is less common than Lyme disease but a potentially more serious illness. This tick has also been known to transmit tularemia and cause tick paralysis. It cannot transmit the spirochetes responsible for Lyme disease.