Black widow spiders are identified by their shiny black bodies and the red hourglass shape on the abdomen. These spiders build abstract webs close to the ground, under patio furniture or play sets. Widows only become aggressive when the web is disturbed, which is why you should never dismantle a web on your own. Their bites are painful and sometimes fatal to pets and small children. If you or a family member have been bitten by a black widow, contact your doctor immediately.