These are not the 'ladybugs' that most people know and love. They are Asian Lady Beetles, similar in appearance, but a royal pain. They do congregate, and will appear in your house by the 100's and 1000's.
When the temperature drops, they will find the smallest openings to get into a house, but will soon die, and if you try to remove them to the outside, they have a tendancy to stain and they do release a foul-smelling odor. If they stay outside, they will also die once the temps drop.