Cedar chips, most often sourced from the aromatic Eastern Red Cedar, are a natural and traditional tool for managing pests in homes and gardens. This wood product provides a chemical-free alternative to synthetic repellents. The characteristic woody scent is the primary mechanism that allows cedar to deter various unwelcome invaders. The effectiveness of cedar chips lies in their ability to release specific aromatic compounds into the air, creating an unpleasant environment for certain insects and other small creatures.
Specific Pests Repelled by Cedar
Cedar chips and oils are known for repelling insects that damage textiles and those that bite. The primary target is the clothes moth; the cedar scent deters adult moths from laying eggs in areas like closets and drawers, preventing larvae from consuming natural fibers.
The natural oils in cedar are also effective against several biting arthropods, including fleas and ticks, making cedar chips a popular choice for pet bedding. The strong aroma repels certain household pests, such as cockroaches and silverfish, by disrupting their sensory navigation. Some types of ants, including Argentine ants, are also deterred by the compounds in cedar. Cedar is sometimes used as a deterrent for rodents like mice and rats, though its efficacy is lower against mammals than against insects.
The Chemical Mechanism of Repulsion
The pest-repelling power of cedar comes from a complex mixture of volatile organic compounds (VOCs) concentrated in the wood’s heartwood. The most significant compounds are sesquiterpenes, which include cedrol, alpha-cedrene, and thujopsene. The primary repellent chemical found in some cedar species is thujone, which gives the wood its distinct aroma.
When these VOCs are released, they interfere with the sensory receptors of many insects, masking the pheromones pests use to communicate and locate food. The intense concentration of these aromatic oils can also irritate the respiratory systems of smaller organisms, making the environment hostile. The deterrent effect is directly proportional to the concentration of these volatile vapors in the air, meaning the fresher the wood, the stronger the repulsion.
Proper Application and Safety Considerations
To maintain the repelling power of cedar chips, they must be used in enclosed spaces like drawers, storage bins, or closets, allowing the volatile compounds to concentrate. Over time, the surface oils evaporate, causing the aroma and repellent effect to diminish. To reactivate the cedar, lightly sanding the chips or blocks will expose the fresh, oil-rich wood underneath, releasing a new burst of aromatic compounds. Alternatively, cedar essential oil can be applied to the chips to rejuvenate their potency.
While cedar chips are generally safe for use around humans and most larger pets, precautions are necessary. The volatile compounds can be respiratory irritants and should not be used as bedding for small animals such as reptiles, birds, or rodents, as it may cause respiratory distress. The chips should also be kept out of reach of infants to prevent ingestion and accidental irritation.