[header] How to get rid of black widow spiders [title] Recognize a black widow spider. [step] Black widow spiders are found across the u.s and canada, and in other temperate regions around the world. They are the most venomous spiders in north america. 
The female is the easiest to recognize--and the most dangerous. She is coal-black, with a spherical abdomen and a red hourglass-shaped mark on her belly.