The interaction between the aromatic plant, lemongrass (Cymbopogon citratus), and bees is often a source of confusion for homeowners and gardeners. The fragrant grass, widely recognized for its citrus scent, appears to exhibit contradictory effects on honeybees, sometimes attracting them and other times driving them away. Understanding this relationship requires looking closely at the specific context of the interaction and the concentration of the plant’s volatile oils. Lemongrass can be both a powerful attractant and an effective repellent, depending on how it is used.
Lemongrass: The Dual Nature of Repulsion and Attraction
The ability of lemongrass to both repel and attract honeybees stems from its chemical resemblance to a natural honeybee communication signal. For beekeepers, the concentrated essential oil is a well-known resource used to attract swarms looking for a new home. When a bee colony grows too large, a portion of the bees will depart with the old queen to establish a new nest, a process called swarming. Beekeepers use a few drops of lemongrass oil in a swarm trap or empty hive to mimic a signal that guides these migrating insects.
This attractive quality is due to the oil mimicking the Nasanov pheromone, a scent worker bees release from a gland at the tip of their abdomen. This natural pheromone is used to orient returning forager bees back to the hive and to mark a suitable nesting site for a swarm. By using a small, controlled amount of the oil, beekeepers effectively trick scout bees into believing the trap is a previously marked, safe location.
However, the powerful, highly concentrated scent of the living plant or a heavily diffused oil acts as a general deterrent for foraging bees. When the scent is too strong or widespread, it can overwhelm the bees’ highly tuned sense of smell, disrupting their ability to locate food sources or navigate. This is why growing lemongrass near a patio or outdoor area can successfully deter unwanted bee activity. The effect is entirely concentration-dependent: a tiny, targeted amount attracts an entire swarm, but a large, diffused volume repels individual foragers.
The Chemical Basis for Bee Interaction
The core of lemongrass’s dual nature lies in its primary volatile organic compound, Citral. Citral is a mixture of two isomeric aldehydes, Neral and Geranial, which give lemongrass its strong, characteristic lemon-like aroma. This compound is structurally similar to several components that make up the honeybee’s Nasanov pheromone.
The Nasanov pheromone itself is a complex blend of several terpenoid compounds, including Geraniol, Citral, and Nerolic acid. Lemongrass essential oil is particularly rich in Citral and Geraniol, components also found in the natural bee pheromone. The resemblance is so close that a synthetic version of the Nasanov pheromone used by beekeepers is often a blend of Citral and Geraniol in specific ratios.
When beekeepers use lemongrass oil, they introduce a high concentration of the chemical components that signal a safe home to the bees. This chemical mimicry is an effective way to communicate with the insects’ olfactory system. Conversely, when this scent is too pervasive, it likely creates an overwhelming or confusing signal that causes foraging bees to avoid the area.
Effective Methods for Using Lemongrass as a Deterrent
To deter unwanted bee activity around human spaces, the key is to use lemongrass in its high-concentration, repellent context. One practical method is to strategically plant the living grass near outdoor seating areas or windows. The constant release of the strong citrus scent helps to create an olfactory barrier that individual foraging bees are less likely to cross.
Using lemongrass essential oil in a topical spray or diffuser is another effective way to apply a high concentration of the repellent scent. A common dilution involves mixing approximately 10 to 15 drops of lemongrass essential oil per ounce of water in a spray bottle. This mixture can be lightly misted around picnic tables, deck railings, or other high-traffic areas to discourage bees and other flying insects.
This strong scent is also effective against other stinging insects, such as wasps and yellow jackets. The general olfactory confusion created by the powerful aroma tends to deter these pests. However, these methods are only effective for deterring foraging insects or preventing them from settling in an area. Once a nest or hive is established, no amount of lemongrass will safely remove it, and professional intervention is the recommended course of action.