Cedar wood has a long history of use in protecting textiles and clothing, often used in storage chests and closet linings. This tradition stems from the wood’s distinct aroma, which naturally deters certain household pests. The effectiveness of aromatic cedar, typically sourced from the heartwood of the Eastern Red Cedar (Juniperus virginiana), results from volatile organic compounds (VOCs) stored within its structure. These compounds are released into the air, providing the pest-repelling property.
The Chemical Compounds That Repel Pests
The insect-repelling power of cedar is rooted in its natural essential oils, a complex mixture of volatile organic compounds. The most potent of these compounds are the sesquiterpenes, including cedrol and cedrene, which are found in high concentrations in the wood’s heartwood. Eastern Red Cedar (Juniperus virginiana) is the preferred species for pest control due to its high oil content. These chemicals are released slowly, creating an environment that is disorienting or irritating to certain insects. The primary compound, cedrol, is a sesquiterpene alcohol that disrupts an insect’s sensory and respiratory systems, acting as a fumigant and repellent. This strong, woody scent is the direct result of these airborne molecules, which serve as the tree’s natural defense mechanism against wood-boring insects and decay.
Specific Insects Affected and Unaffected
Aromatic cedar is most effective as a deterrent for insects that damage stored fabrics, particularly clothes moths and certain species of carpet beetles. The volatile oils disrupt the life cycle of the common clothes moth (Tineola bisselliella), especially the destructive larval stage. This makes cedar-lined storage a traditional choice for protecting woolens and textiles. Cedar’s action is primarily repellent, driving pests away from the area. High concentrations of the compounds can be toxic to newly hatched larvae, but adult insects usually avoid the scent entirely.
The aromatic wood is notably less effective against insects that pose major structural threats or those that bite. Cedar wood offers resistance to termites, but it is not a complete barrier, and these pests will still consume the wood under certain conditions. While cedarwood oil shows some efficacy against biting insects like mosquitoes and ticks in laboratory settings, the solid wood is largely ineffective at repelling them in an open environment. The repellent effect is highly specific. Therefore, cedar should not be relied upon to control general household pests such as cockroaches, ants, or spiders. Its use is best confined to protecting stored goods in enclosed spaces where the oil concentration can remain high.
Maintaining and Maximizing Cedar’s Repellent Power
The effectiveness of cedar wood is directly tied to the concentration of its volatile oils, which are released from the surface and evaporate over time. As the surface layer is exposed to air, the repellent power gradually diminishes. This means an old cedar chest or block may lose its ability to deter pests after several years, especially if the surface has become dusty or sealed. To maximize the wood’s natural protection, the surface must be renewed periodically to expose a fresh layer of oil-rich wood.
A simple maintenance technique is to lightly sand the cedar surface with fine-grit sandpaper. This action breaks open the wood cells, releasing a new burst of the aromatic cedrol and cedrene compounds. Cedar blocks or hangers should be refreshed approximately once a year to sustain a sufficient concentration of repellent oils. Alternatively, concentrated cedar essential oil can be lightly applied to the wood surface to replenish the volatile compounds. When purchasing cedar products, ensure they are made from solid, untreated Eastern Red Cedar heartwood, as processed products may lack the necessary oil concentration for long-term effectiveness.