Two culprits commonly damage cloth: the casemaking clothes moth, shown at right, and the webbing clothes moth. These reclusive, small critters (about 1/4" long with a 1/2" wingspan) don't resemble your standard porch-light moths. If you see them at all, it may already be too late to save your sweaters because it's the larvae, rather than the adult moths, that munch on wool, fur, and feathers.
So how does aromatic cedar contribute to your pest-control solution? When concentrated in a tightly-sealed space, such as a blanket chest, the vapors from this wood species will kill hatching moth larvae. But those vapors have little or no effect on larger larvae, adult moths, or eggs, and less effect still in wide-open areas, such as closets.
That said, it has been found that aromatic cedar blocks bugs no better than simply sealing uninfested clothes in a plastic container or bundling them in taped-up butcher paper.