content: Because they eat all your food and all the food that is there for farm animals. It doesnt matter how much you have they will eat non stop. If you have mountain of it stored they will just multiply insanely fast ant eat it all eventually. If thats not enough for you they also carry many diseases. And yes... they will get into your home. They will chew thru boxes, plastic... to get to your food and when they do even if they dont eat it all right away you have to trow out everything they touched. You dont wana eat rat and mice poop, piss and saliva. They also chew on your furniture and cables.