The belief that the aromatic scent of cedar acts as a universal insect repellent often leads homeowners to assume it will deter bees and other pollinators. This assumption stems from cedar’s proven effectiveness against certain household pests, such as moths and termites. To understand the relationship between cedar and bees, it is necessary to examine the specific scientific evidence regarding the wood’s composition and biological impact.
The Scientific Consensus on Cedar and Bees
Scientific investigation concludes that cedar wood is not an effective repellent for foraging honey bees or native pollinators. Cedar’s protective compounds are well-documented to repel other arthropods, including ticks, ants, and clothes moths. However, the lack of repellency toward bees is evident, as Western Red Cedar is a popular material for constructing modern beehives globally due to its durability and resistance to rot.
Beekeepers frequently use cedar mulch around hives to reduce ground-dwelling pests without observing negative effects on honey bee colonies. Field observations, such as feral colonies thriving inside hollow cedar trees, support the conclusion that the wood poses no threat to their nesting or navigation. The low concentration of volatile compounds released by solid wood does not interfere with a bee’s primary motivation of locating nectar and pollen sources.
Chemical Compounds Responsible for Scent
Cedar’s distinctive aroma and pest-fighting properties come from volatile organic compounds (VOCs) known as terpenes, including alpha-cedrene, beta-cedrene, and the alcohol cedrol. The tree produces these oils as a natural defense mechanism against wood-boring insects and fungi. These compounds disrupt susceptible insects by acting as neurotoxins, interfering with pheromones, or disrupting the respiratory tract.
The mechanism by which cedarwood oil affects pests like mosquitoes and ticks involves blocking octopamine neurotransmitter receptors. Octopamine regulates essential life functions, such as heart rate and movement, in invertebrates. However, beneficial insects, including honey bees and butterflies, do not utilize this specific neurotransmitter system in the same way as the targeted pests. This difference in neurobiology explains why concentrated cedar oil can be toxic to some insects yet benign to bees.
Distinguishing Cedar Wood from Concentrated Essential Oil
The confusion regarding cedar’s effect on bees often arises from the difference in concentration between solid wood and essential oil. Solid cedar wood, such as lumber or garden mulch, releases a low and slow concentration of volatile oils into the air. The natural concentration of active compounds is too low to act as an effective repellent barrier for a foraging bee.
In contrast, cedar essential oil is a concentrated product obtained through extraction methods, often from species like Eastern Red Cedar (Juniperus virginiana). This oil contains a high percentage of active terpenes and cedrol, making it potent for commercial pest control applications. Even at high concentrations, these essential oil products are marketed as safe for beneficial insects because their chemical mechanism does not target the specific neurological pathways used by bees.