Among the arthropods commonly kept as pets, millipedes may be the easiest to feed. Millipedes are herbivores.
You can feed your millipede a variety of fruits and vegetables. Slice and peel apples, cucumbers, squash, melon, tomatoes, peaches, and bananas before giving them to your pet millipede. Leaf lettuce also provides a good snack. Some millipedes do well on food pellets for birds or even fish flakes.
Your millipede needs calcium, which is essential for it to molt and properly form a new exoskeleton. Dust fruit pieces with calcium powder, which you can purchase at most pet stores. Some people prefer to add cuttlefish bone shavings, another good source of calcium, to their pet millipede's food.
You will need to feed your millipede every day, but give it only as much food as it will consume in one night. Remove any unfinished food in the morning to keep the terrarium clean.
For more on keeping millipedes as pets, read my Guide to Caring for Pet Millipedes.