Source: U.S. National Park Service. Available online: http://www.nps.gov

Black widow spiders (Latrodectus mactans) are found throughout the United States. Female black widows are long-legged, shiny, coal-black spiders with an orange, red, or yellow hourglass shape on their underside. Female black widows are usually about 1.5 in. (3.8 cm) across but may be smaller.