I've never noticed any kind of substantial damage the rotting wood even with large amounts of them in a very small space - I think they actually feed on fungi that may be starting on it or bits that have decayed to a point where they are very, very soft. I wouldn't be concerned at all about wood structures in the vivarium with them = ) I probably made them seem like termites or something by saying they "munch" when in reality it just more of a hiding and moisture resevoir that also serves as a place where food may grow.