Lemongrass, derived from the Cymbopogon genus, is a recognized and effective natural option for repelling mosquitoes. The essential oil extracted from this aromatic grass is commonly used in commercial and homemade preparations to deter various biting insects. This article explores the science behind lemongrass’s repellent qualities, how it works, and the best practices for its use.
The Active Ingredient: Citronella
The mosquito-repelling power of lemongrass products stems from the concentration of compounds found in its essential oil, often referred to as citronella oil. While the culinary lemongrass (Cymbopogon citratus) contains high levels of citral, the species most frequently distilled for commercially used repellent oil is usually Cymbopogon nardus or Cymbopogon winterianus. These two related grasses yield the oil known primarily as Citronella.
The key volatile organic compounds responsible for the strong, citrus-like scent and repellent action are citronellal, citronellol, and geraniol. Citronellal is often the most abundant compound in the oil, providing the characteristic strong aroma that mosquitoes find offensive.
Scientific Efficacy and Mechanism of Action
The mechanism by which lemongrass oil repels mosquitoes involves disrupting the insect’s ability to locate a host. Mosquitoes are primarily attracted to humans by sensing chemical cues, specifically the carbon dioxide we exhale and the lactic acid present in our sweat. Lemongrass compounds interfere with the mosquito’s olfactory receptors, effectively masking these attractive human scents.
Studies confirm that lemongrass oil can provide a high level of initial protection, with a 10% formulation showing up to 95% relative protection immediately after application. The major limitation, however, is the high volatility of its active compounds, meaning they evaporate quickly from the skin. This rapid evaporation causes a significant drop in effectiveness over a short period compared to synthetic repellents.
Protection times for lemongrass-based products are relatively short, often requiring frequent reapplication to maintain efficacy. A 10% lemongrass oil formulation, for instance, has been found to provide complete protection for around 60 to 90 minutes against certain species of mosquitoes. For continuous protection during outdoor activity, reapplication is generally recommended every one to two hours.
Formulations and Practical Application
Lemongrass oil is incorporated into a diverse array of mosquito-repelling products available to consumers. These include topical applications such as sprays, lotions, and roll-ons, where the essential oil is diluted in a carrier base for direct skin contact. Area repellents like candles, coils, and diffusers are also common, releasing the volatile compounds into the air to create a protective zone.
To maximize the effectiveness of topical applications, a dilution rate of 5% to 10% essential oil in a carrier oil or lotion is generally advised. Applying the product generously and evenly to all exposed skin surfaces is necessary for a temporary barrier. Frequent reapplication is the single most important factor for success when using lemongrass oil-based repellents.
Planting lemongrass itself around a perimeter can contribute to a pleasant aroma but is considerably less effective than using the concentrated oil. The plant does not naturally emit enough volatile oil to create a significant protective field. For best results, use commercial or properly diluted essential oil products.
Safety Profile and Regulatory Context
Lemongrass oil is generally considered safe for human use and is often listed as Generally Recognized as Safe (GRAS) for consumption by regulatory bodies. In the context of pest control, the essential oil is classified by the Environmental Protection Agency (EPA) as a biopesticide with a low-risk, non-toxic mode of action.
While it is low in toxicity, the pure, undiluted essential oil can cause skin irritation or allergic reactions in some individuals. Proper dilution with a carrier substance is necessary before applying it to the skin. Consumers with sensitive skin should always perform a patch test before widespread use of any essential oil-based repellent.