it might be a stage… but some bunnies are chewers their entire lives. it’s one of the ways that they play. the most important thing you need to do is bunny-proof. this involves manipulating the environment so FIRST of all, the bunny is safe, and secondly, your stuff is safe. wires have to be covered or blocked off (or both!) for the determined bunny. biting into a live wire can kill a bunny. anything you don’t want chewed must be picked up or moved out of the bunny area. if it’s in their reach, it’s fair game. the bunny info section at the top of the page has a section with tips on bunny-proofing…
along with bunny-proofing, the bunny has to be given alternatives that are safe, so like they said above… toys, phone books, and boxes all work great. if the bun starts to chew on something that is off-limits, distract them with a toy.
when rabbits reach puberty, the destructive behavior sometimes kicks up a notch or two. oftentimes, altering can reduce the unwanted behaviors. it’s not always 100% b/c some buns will always love to chew, but it can definitely help, and it is good for the rabbit’s health as well.