Hi Jana,

You have observed elm leaf beetles (Xanthogaleruca luteola). You can rest easy that these insects pose no threat to anyone or anything in your home. There are so many in your home probably because there is an elm tree nearby, and insects are attracted to man-made structures for their warmth. 

The best way to deal with them would be to seal up the cracks/crevices through which these beetles are entering your home. These entry points are often along the poorly insulated borders of windows and doorways. As for the beetles already in the house, physical removal is your best bet. You can hand-pick them, vacuum them, and/or lay out sticky traps/glue boards. I strongly discourage the use of insecticides here. 

If this invasion is a consistent problem and the elm tree which produces the beetles is on your property, you may consider cutting down that tree. But only as a last resort. If there are other elm trees nearby, the beetles may continue to invade nonetheless. Preventing them from entering the home is the best long-term solution. Let me know if you have further questions.