Baby squirrels eat milk and other food items which their mothers feed them. They stay in the nest or drey with their mothers until they become adults.  If you find a baby squirrel in your yard and you want to help the poor guy.  First, check it the baby is dehydrated. You can find out by pinching his back up that if the skin remains wrinkled then it means dehydration. You can hydrate the squirrel by giving it Pedialyte.  After hydration, you can feed the squirrel some milk. Feed them Esbilac Puppy Formula, which is a powder formula, and is best for baby squirrels. However, under normal circumstances may not see baby squirrels that often because they are raised by their mothers in the nest during winter or in the balls of leaves, called a drey, in the summer. They don't emerge from the nest until they are fairly close to adult size.