The female black widow stores sperm, producing more egg sacs without mating. Some females live more than three years. They hold from 25 to 900 or more eggs, which have an incubation period of 20 days. The spiderlings disperse shortly after emerging, tearing an opening in the egg sac and stay near the sac. After several hours, these second instar spiderlings balloon to the ground and scatter.
Growth requires two to three months, with older females dying in autumn after egg laying.
Of all spiders, the Black Widow is the most feared. The female's venom is especially poisonous to people. Despite its reputation, this spider often attempts to escape rather than bite, unless it is guarding an egg mass or if it is cornered and pressed. The male black widow will not bite you. During the period shortly following mating and laying of eggs, the female black widow can be a little cranky and hungry.