There are five species of widow spiders. Black widows prefer quiet, dark places such as basements, outhouses, or sheds where they can find ample hiding places. Black widows are the largest of the irregular web-weaving spiders. The web is quite strong and provides a place for the female to reside.
Females are much more likely to bite when they are protecting their egg sac.
Females lay 250 eggs that hatch in approximately 20 days. The spiderlings may remain in the egg sac for one month before they emerge. Females mature after 6 to 8 molts and males mature after 3 to 6 molts. Upon reaching maturity, males only live about three months while females may live as long as three years. A bite from a black widow delivers a dose of neurotoxin that can cause severe muscle cramping and difficulty breathing.