What do beetles eat ? - Sport & Outdoor - Others

"Beetles eat all kinds of food. Most are specialists in few kinds, but some, like ground beetles, eat lots of things. Most beetles eat plant parts, either leaves or seeds or fruit or wood. Many are predators on other small animals. Some eat fungus, and there are a bunch of species that eat dung. Sometimes the larvae eat different foods than the adults do."

http://www.biokids.umich.edu/critters/Coleoptera/