While black widow spiders are well known for inflicting painful and medically significant bites to humans, the spiders are not well understood by the public. This is true even in Arizona where the highly venomous spiders can be found on occasion within homes. Internet sites happen to be one of the most significant sources of disinformation concerning black widow spiders. For example, a quick Google search will tell you that “22 types” of black widows can be found just within the city limits of Phoenix and Tucson. However, the United States is home to only 3 “black widow” species, while only one single black widow species, not 22, can be found within the state of Arizona. This species is known as Latrodectus hesperus, or the western black widow, as it is more commonly called. It should also be noted that black widows are categorized in the genus Latrodectus, also known as “widow spiders.” In all, only two widow spider species can be found in Arizona. The other species being the recently introduced “brown widow.”
Black widows are often considered their own species because all three species in the US are referred to by the same common name. These three species are commonly known as southern black widows, western black widows, and northern black widows. Both southern and northern black widows can be found in the eastern half of the US. The southern variety is most often found in areas east of Texas and up north to Virginia, while the northern black widow’s habitat is largely limited to the entire eastern seaboard and into parts of the midwest. The western black widow can be found along the west coast, particularly in the desert southwest. In addition to the western black widow species, another widow species that is not native to the US has been found along the southernmost border of the country. This species is commonly referred to as the brown widow, and it is not known to many residents of Arizona because it has only recently been found in the state. The brown widow was most likely introduced accidentally into the region via shipments of plant matter. Finally, the red widow is a species that can only be found in southern Florida. So far, a total of 31 widow species have been found worldwide.
Have you ever spotted a western black widow within your home? Were you aware that a non-native widow spider species exists within Arizona?