One of the egg sacs of our American House Spider has hatched! There are probably 100 babies.
According to Insects and Spiders of the World by Robert S. Anderson, Richard Beatty, and Stuart Church, the spiderlings (baby spiders) will stay put INSIDE the egg sac until they shed their first skin. As spiders grow they must shed skin in order to get bigger. Their hard outside shell doesn’t get any bigger, so they need to grow a new one. As they sit there, some of them might even eat each other! Once they are ready they leave the egg sac but still stay with their mother for a while until they get bigger. Eventually, they will leave to find their own homes and make their own webs.