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 common name 'black widow spider' is most commonly used to refer to the three North American species best known for their dark coloration and red hourglass pattern, it is occasionally also applied to several other members of the Latrodectus (widow spider) genus in which there are 31 recognized species including the Australian red-back, brown widow spider (sometimes called the gray widow), and the red widow spider.
In South Africa, widow spiders are also known as the button spiders.
Currently, there are three recognized 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).
Adult female black widow spiders are shiny black with an hourglass shaped marking on the underside of its abdomen which, although most commonly red, may range in color from white to yellow to various shades of orange and red.
They also bear a small, usually red (colors vary) dot near the spinerettes, which is separate from the hourglass.
In L. variolus, the two halves of the hourglass shape may be separated into two separate patches.