Cinnamon, a common kitchen spice, is frequently suggested as a natural way to deter household pests like flies. This claim is based on the spice’s strong, aromatic properties, which are thought to be unwelcome by many insects. The appeal of using cinnamon as a repellent lies in its natural origin, providing an alternative to synthetic chemical sprays. This exploration investigates the scientific basis for cinnamon’s effect on flies and offers practical methods for its application.
Active Compounds and Repellent Mechanism
The fly-repelling properties of cinnamon are attributed to the volatile organic compounds (VOCs) concentrated in its essential oil. The primary active component is cinnamaldehyde, which makes up 60–90% of the oil’s composition. Eugenol is another significant compound, often comprising a substantial percentage of the oil distilled from cinnamon leaves, and is also known for pest-controlling effects. These compounds function by disrupting the flies’ sensory systems, particularly their highly sensitive olfactory receptors.
Flies rely heavily on their sense of smell to locate food sources and egg-laying sites. The intense aroma of cinnamaldehyde and eugenol overwhelms these senses, making the treated area undesirable or “invisible” to the insect, causing them to avoid it. While high concentrations of cinnamon oil can be insecticidal, the primary action in household use is repellent, discouraging flies from landing or entering a space.
Practical Ways to Apply Cinnamon Against Flies
The most effective way to utilize cinnamon’s repellent qualities is through its highly concentrated essential oil. One common method involves using a diffuser to disperse the volatile oil molecules into the air, creating a consistent, fly-deterring aroma indoors. For a localized barrier, a diluted topical spray can be created by mixing 10 to 15 drops of cinnamon oil with about 240 milliliters of water. This mixture can be lightly spritzed around fly entry points, such as door frames, window sills, and waste areas.
Cinnamon sticks or ground powder offer simpler, low-concentration options for smaller areas. Placing cinnamon sticks near fruit bowls can deter fruit flies, and sprinkling ground cinnamon powder in areas like window tracks or counter edges may help create a temporary barrier. Since the active compounds are volatile, applications must be refreshed regularly to maintain efficacy. Essential oils in sprays require reapplication every few days, as the scent and repellent power fade quickly.
Safety Considerations and Real-World Limitations
While cinnamon oil is a natural product, its concentrated form requires careful handling to avoid potential health risks. Direct contact with undiluted cinnamon essential oil can cause skin irritation or allergic reactions in humans. Furthermore, cinnamon essential oil is toxic to household pets, especially cats and dogs, whether inhaled, ingested, or applied topically. Pet owners should exercise caution and avoid using cinnamon oil in areas where their animals frequent, or opt for pet-safe alternatives.
The real-world effectiveness of cinnamon as a fly repellent is limited by its inherent volatility and the required concentration level. The repellent effect is temporary because the active compounds evaporate quickly, necessitating frequent reapplication, especially outdoors. While high-concentration essential oil can be an effective deterrent, common grocery store cinnamon powder contains a much lower percentage of active compounds. This powder may offer minimal, if any, measurable repellency against flies. Cinnamon should be viewed as a temporary deterrent and a supplement to pest control, not a standalone solution for a significant fly infestation.