Adult roaches munching on wood chips and wood decorations?

My adult roaches are chewing on the wood chips and wood decorations in my tank, actually eating them! I give them fruits,veggies,starches, and protein each week (never the same thing every day) They also get plenty of water, I mist the tank every night and they drink the droplets on their bodies. I cant understand why they are so interested in the wood? Should I try giving them a small dish of peat moss to munch on, I dont think any rotting wood outside is safe to give them.

Wood is a more natural diet for them.

So like I asked, give them some peat moss?