Amblyomma americanum, commonly called the lone star tick, has been widely-distributed in the southeastern United States for many years. Distribution of this species apparently did not extend to New York State until the 1970s, after which the northern distribution in New York was limited to Long Island (Suffolk and Nassau counties), where it has become locally abundant. Since then, there has been just one published record from New York State, in Westchester County, just north of New York City. From 1988 to 1996, through the Tick Identification Service of the New York State Department of Health, 244 specimens of A. americanum were documented from mammalian hosts in 46 of the 62 New York State counties. These records extend the distribution of A. americanum to several more northern and western New York State counties. With a demonstrated expansion of geographic distribution, continued surveillance of A. americanum is of great public health importance. Besides being a severe pest where abundant, this species is a probable vector of human monocytic ehrlichiosis (HME), and a suspected vector of Borrelia lonestari, the etiologic agent of a
Lyme disease-like illness.