The answer to the question, “What do mice eat?”, is an easy one. Anything and everything. And, you know that is the truth if you ever have had the unfortunate experience of having your house overrun by mice. Mice multiply very quickly so if you have a couple of mice, you are going to have dozens in no time at all. A female has, on average, ten litters a year of 7-10 mice per litter. You don’t have to start out with very many mice to have a large population in no time.