I placed the egg sac in one of those clear plastic soup containers, and the most surprising thing was that the mantises hatched in successive waves. They didn't all hatch at once, and it wasn't like a trickle of mantises either. It would be kinda cool if the mantises somehow knew that they were stuck in a plastic container and purposely only hatched enough so they wouldn't be overcrowded although I have no idea how they would possibly know this.