The female of Latrodectus mactans. It is native to the southern U.S. but has been reported throughout the country. It prefers to live in woodpiles and other locations where it is well hidden. It is glossy black with a brilliant red spot, usually shaped like an hourglass or two triangles, on the undersurface of the abdomen (Southern black widow), or a row of red, white or yellow spots down the middle of the abdomen with two crosswise bars (Northern black widow). Its body measures about 1 cm and its leg spread can reach 5 cm.