Black widows are a shiny black spider with a notorious red hourglass shape on their underbellies. While a female spider is about 1.5 inches long, the male spider is half that size. Males are also lighter in color with pink or red spots on their backs.

Another distinguishing feature is the black widow's comb feet used for ensnaring prey in silk webs. Their fourth pair of legs have several stiff, short hairs on them resembling a comb. Black widows are a nocturnal species, using the daylight hours only for spinning webs. They can sometimes be found hanging from their web exposing their bright underside to scare away predators. Their webs are messy, irregular and indicate the presence of the spider.

Black widows are the most venomous spiders in North America and get their name from the female's tendency to eat her mate. In humans, symptoms of a bite include nausea, aches and difficulty breathing; however, bites are rarely fatal. Fatalities are most common in infants, the elderly and infirm. They only attack humans when provoked or disturbed.

Black widows live in dark and dry areas. They are commonly found in garden sheds, barns, basements, trash and outhouses. Irregular webs underneath lawn furniture or in the corners of a garage or outbuilding may indicate the presence of a black widow.