The black widow spider (Latrodectus spp.) is a spider notorious for its neurotoxic venom. It is a large widow spider found throughout the world and commonly associated with urban habitats or agricultural areas. Although the name 'black widow spider' is most commonly used to refer to the three North American species best known for their dark coloration, black hair and red hourglass pattern, occasionally it is applied to several other members of the Latrodectus (widow spider) genus in which there are 31 recognised species including the Australian red-back, brown widow spider (sometimes called the grey widow), and the red widow spider. In South Africa, widow spiders are also known as the button spiders. Currently, there are three recognised species of black widow found in North America: The southern black widow (L. mactans), the northern black widow (L. variolus), and the western black widow (L. hesperus). As the name indicates, the southern widow is primarily found (and is indigenous to) the southeastern United States, ranging from Florida to New York, and west to Texas, Oklahoma and they run particularly rampant in parts of Arizona. The northern widow is found primarily in the northeastern U.S. and southeastern Canada (only on the Bruce Peninsula), though its ranges overlap that of L. mactans quite a bit. The western widow is found in the western half of the United States, as well as in southwestern Canada and much of Mexico. Prior to 1970, when the current taxonomic divisions for North American black widows were set forth by Kaston, all three varieties were classified as a single species, L. mactans. As a result, there exist numerous references which claim that "black widow" (without any geographic modifier) applies to L. mactans alone. As common usage of the term "black widow" makes no distinction between the three species (and many laypersons are unaware of the differences between them), and as the three species have much in common, this article treats all three species of black widow equally. Except where otherwise indicated, the remainder of the article applies to all three of the above species.