Q. My aunt gave me a cedar chest that she’s had since she got married. If I store my wool clothes and blankets in there, will the cedar protect them from clothes moths?
A. Unfortunately, the effectiveness of cedar chests in repelling clothes moths is overstated. Not that cedar doesn’t work, it just doesn’t work for very long, or very well. The heartwood of red cedar does contain volatile oils that will kill clothes moth larvae…when the oils are in high concentration. A relatively new, well-made cedar chest can protect from clothes moths for a while, as long as it is kept tightly closed and the items are not already infested when placed inside.
Studies have suggested that even a new cedar chest kills only small clothes moth larvae, not larger larvae, eggs, or pupae. If already-infested woolens were placed in a new cedar chest, the larvae could survive and the infestation could continue. Cedar oils also don’t repel adult clothes moths or other fabric pests such as carpet beetles.
An old cedar chest like your aunt’s will not protect clothes or woolens from clothes moths. One study suggested that a cedar chest more than three years old is practically useless for killing clothes moth larvae. Cedar-lined closets are even less effective because they are not airtight and can’t keep adult clothes moths out. Having a storage chest that is tightly constructed is probably more important in keeping clothes moths out than whether or not the chest is made of cedar.
You can help restore the cedar’s repellency (but only somewhat) by lightly sanding the cedar or by applying cedar oil. Bottom line is, don’t put your faith in cedar to repel fabric pests. But at least it does smell nice!
While we’re on the topic, people often don’t use moth balls effectively either. Moth balls, flakes or crystals containing napthalene or paradichlorobenzene are commonly used to protect clothes in storage. As these chemicals evaporate, they produce vapors that, in high enough concentration, will kill insects. But the vapors achieve this high concentration only in an airtight container. If you sprinkle moth balls or crystals on shelves or even into a closed cardboard box, the vapors will weakly repel adult clothes moths, but will probably not kill any larvae already in the woolens.