Lemongrass, derived from the Cymbopogon genus, is a tropical plant known for its distinct, citrusy aroma. This fragrance has led to its use as a natural insect deterrent. Science generally supports the belief that bugs dislike lemongrass, but its effectiveness depends on the concentration of active ingredients and the method of application.
The Compound That Repels Insects
The insect-repelling properties of lemongrass are primarily due to the volatile organic compounds found within its essential oil, often referred to as citronella oil. The most prominent of these compounds is citronellal, which is a major component, alongside citral, geraniol, and citronellol. These molecules are released into the air when the plant’s leaves are crushed or the essential oil is diffused.
The intense, lemony scent acts by disrupting the insects’ finely tuned sensory systems, particularly in pests like mosquitoes and ticks. This disruption works in two primary ways: first, the strong odor physically masks the scents that attract insects to humans, such as carbon dioxide and lactic acid. Second, the compounds can act as an irritant or neurotoxin, directly interfering with the insect’s neural pathways, making it difficult for them to locate a host. Citral is considered a key contributor to this insecticidal and repellent activity.
Scientific Evidence of Effectiveness
Scientific research confirms the efficacy of lemongrass essential oil, especially against mosquitoes, which are the most commonly targeted pest. Studies focusing on species like the Aedes aegypti mosquito, a vector for diseases, have demonstrated that the essential oil can significantly reduce biting rates and cause mortality. The repellent activity of the main components, such as citronellal, geraniol, and citronellol, has been shown to reach as high as 78% against certain mosquito species.
The effectiveness, however, varies greatly depending on the form of use. Pure lemongrass essential oil or high-concentration commercial products offer the strongest protection. Simply planting the grass in a garden is less effective as a personal repellent because the volatile oils are not released in a high enough concentration without crushing the leaves. While highly effective initially, the volatility of the natural compounds means that reapplication is necessary, often requiring more frequent use than long-lasting synthetic repellents.
How to Use Lemongrass for Pest Control
There are several practical methods for utilizing lemongrass to manage pests, suitable for both indoor and outdoor environments. One common approach is to use the pure essential oil in diffusers or candles, which releases the active repellent scent into the surrounding air. This creates a localized zone of protection that helps deter insects from entering a specific area.
For personal protection, the essential oil must be diluted before applying it to the skin. A few drops of lemongrass essential oil can be mixed with a carrier oil, such as coconut or almond oil, to create a topical repellent. Alternatively, a spray can be made by combining the oil with water and an emulsifier like witch hazel. Always perform a patch test on a small area of skin first, as the concentrated oil can cause irritation.
Planting lemongrass itself in pots or garden beds around a home’s perimeter can offer a low-level, natural deterrent. For a more immediate effect, the leaves can be crushed to release the concentrated oils. Using commercially prepared sprays containing lemongrass oil can also be an effective way to treat surfaces or clothing.