The dark-colored heartwood of red cedar contains natural oils that help kill clothes-moth larvae, but this alone won't protect clothing. It's not effective against carpet beetles, and, with moths, it kills only young larvae, not older ones or eggs. The effect also fades as the scent does. You can replenish the scent of boards, closets, and chests by sanding the wood lightly or dabbing on cedar oil, but there is no way to know if you've added enough. If you have a cedar chest, it's best to think of it as a reasonably airtight storage container-and only keep clean fabric inside it. Again, wrap items in clean cotton before storing them.