The common spice, cloves, are cited in folk remedies for keeping pests at bay. These claims have a scientific basis, as the aromatic flower buds of the Syzygium aromaticum tree contain powerful compounds that naturally deter many insects. The effectiveness of cloves is highly dependent on whether the whole spice or its concentrated oil is used, and how it is applied. Understanding the chemistry behind this natural deterrent offers insight into its practical application.
The Chemical Compound Responsible for Repellency
The primary active component in clove oil is eugenol, a phenolic compound that can constitute between 70% and 85% of the oil’s composition. Eugenol is responsible for the characteristic strong, spicy aroma of cloves, and this potent scent disrupts the sensory systems of insects by focusing on their olfactory (smell) receptors.
Eugenol strongly activates certain olfactory receptor neurons (ORNs) in insects, overwhelming their sense of smell. This intense activation effectively scrambles the signals the insect relies on to locate a host or find food sources. In addition to being a repellent, eugenol also acts as a contact insecticide, capable of disrupting the insect’s nervous system, leading to paralysis or death, particularly in concentrated forms.
Specific Insects That Cloves May Repel
Clove oil demonstrates effectiveness against a wide spectrum of insect pests, but results vary by species and concentration. Mosquitoes are one of the most studied targets; research shows that a 10% clove oil solution can provide near-complete repellency against certain species, such as Aedes aegypti, for up to two hours. Protection duration is generally shorter than that offered by synthetic repellents.
Beyond mosquitoes, clove oil deters and kills household pests like flies, ants, and cockroaches. Its strong fumigant action is particularly effective against houseflies, disrupting their feeding and breeding cycles. For crawling insects like ants, the odor of clove oil can obliterate the scent trails they use for foraging and navigation.
Other pests, including mites, ticks, and stored-grain weevils, are susceptible to concentrated clove oil’s insecticidal properties. The effect’s strength relates directly to eugenol concentration, making clove oil significantly more potent than whole cloves. While whole cloves offer a mild deterrent in small areas, concentrated oil is required for measurable results.
Practical Methods for Using Cloves as a Repellent
Cloves can be utilized for pest control through several methods, ranging from simple placement to oil-based applications.
Indoor Placement
For a mild, aromatic deterrent in indoor spaces, pomanders can be created by studding whole cloves into citrus fruits like oranges or lemons. These decorative items release the clove aroma as the fruit dries, working well near entryways or on windowsills. Their repellency is limited to a small area.
Diffusing and Spraying
For concentrated indoor use, clove essential oil can be diffused using an ultrasonic or heat diffuser to repel airborne pests like flies and mosquitoes. A simple non-topical spray is made by boiling whole cloves in water, allowing the mixture to cool and steep, then straining the liquid into a spray bottle for use on surfaces. This extracts eugenol, creating a mild repellent spray.
Topical Application
To create a topical repellent, clove essential oil must be properly diluted in a carrier oil, such as olive or coconut oil, to prevent irritation. A common recommendation is a dilution ratio of approximately 1 part clove oil to 10 parts carrier oil (roughly 10% concentration), which should always be patch-tested first. The mixture is applied sparingly to exposed skin areas for temporary protection.
Safety Considerations for Clove-Based Repellents
While clove oil is a natural product, its high concentration requires careful use to prevent adverse health effects. Undiluted clove essential oil is highly potent and can cause skin irritation, redness, or chemical burns upon direct contact. Always ensure the oil is significantly diluted with a carrier oil before applying it topically.
A significant safety concern exists regarding pets, particularly cats. Eugenol can be toxic to both dogs and cats if ingested or applied in high concentrations. Cats specifically lack the liver enzymes necessary to metabolize many essential oil compounds. Ingestion or excessive inhalation can lead to symptoms like vomiting, lethargy, or liver damage. When diffusing clove oil indoors, ensure the area is well-ventilated and that pets, especially cats, can leave the room if the scent becomes too overwhelming.