What do worms eat?

From WormWiki

Though they may eat their bedding and the food in the bin, worms actually receive nourishment from the microbes that decompose the food -- the bacteria, fungi and single-celled organisms that make food "rot." The bedding and food that bin owners put inside are hosts for these microbes, and the worms themselves help make the conditions right for the microbes, which thrive inside a worm bin. These microbes are generally harmless to humans, although it's a good idea to wash your hands thoroughly after working in a bin, and you can also wear gloves for comfort. For information on what sorts of food to put into a bin, see What to feed your worms.