Black widows are spiders. Their scientific name is "Latrodectus mactans," and they share the "Latrodectus" name with several similar spiders (sometimes called "widow spiders). The female is shiny black and has a round abdomen with a red hourglass pattern on its underside. They are closely related to another group called "Steotoda" (sometimes called "false widow spiders) that contains species that are not dangerous to humans. All of the true widow spiders can give bites that are harmful to human beings and may kill children or people who are not in good health.