Cedarwood has long been recognized for its ability to protect natural fibers from clothes moths. The scientific basis for this deterrence lies in specific compounds within the wood that create an undesirable environment for these pests. Cedar does not kill moths; instead, it acts as a deterrent, encouraging them to seek other locations for laying eggs and feeding.
The Unique Chemistry of Cedarwood
The distinct aroma of cedarwood, particularly from species like Eastern Red Cedar (Juniperus virginiana), comes from a complex mixture of volatile organic compounds (VOCs). Cedrol is a prominent sesquiterpene alcohol that gives the wood its characteristic scent and insect-repelling qualities. Other compounds like thujopsene, alpha-cedrene, and cadinene also contribute to this aromatic profile and deterrent effect. These chemicals are primarily stored within the heartwood cells of the cedar tree and are slowly released into the air as the wood matures.
The concentration of these volatile compounds can differ based on the cedar species, the tree’s age, and the specific wood part. As these compounds evaporate, they create a vapor barrier around the cedar item. This continuous, slow release of natural chemicals provides the long-term protective effect associated with cedar products. Eastern Red Cedar, commonly used for moth repellents, contains a significantly higher amount of these essential oils compared to other woods.
How Cedar’s Compounds Deter Moths
Cedar’s effectiveness against clothes moths primarily stems from its volatile compounds impacting the insects’ sensory systems. Clothes moths, such as Tineola bisselliella, are attracted to natural fibers like wool, silk, and fur because these materials contain keratin, a protein they can digest. The volatile organic compounds released by cedarwood act as strong irritants to the moths’ olfactory receptors, which are responsible for their sense of smell.
When moths encounter the high concentration of cedrol and other compounds, their ability to locate suitable food sources or egg-laying sites is disrupted. This sensory interference makes the environment unappealing, compelling moths to avoid the area rather than lay eggs on or feed from nearby items. While these compounds do not kill the moths, they interfere with their natural behaviors, effectively driving them away. This creates a protective zone around cedar products, safeguarding textiles.
Sustaining Cedar’s Effectiveness
Over time, the volatile organic compounds responsible for cedar’s moth-repelling properties gradually dissipate from the wood. This natural process reduces the wood’s characteristic scent and its deterrent effect. The wood’s surface can become less potent as accessible compounds evaporate or become covered by dust.
To restore cedar’s effectiveness, lightly abrade the wood surface with fine-grit sandpaper. This action removes the depleted outer layer, exposing fresh wood cells with more active compounds. Another method involves applying cedar oil, concentrated with these volatile compounds, directly to the wood. Regular maintenance, such as sanding every few years or replenishing with cedar oil, ensures cedar items continue to release deterrent chemicals, maintaining their protective qualities.