Are Citronella Candles Effective?

Citronella candles are a type of candle that contains citronella oil, which is an essential oil derived from different species of Cymbopogon or lemongrass. The main purpose of citronella candles is to act as an insect repellent, especially against mosquitoes.

When the candle is lit, the heat helps to diffuse the citronella oil into the surrounding air. The strong, lemon-like aroma of the citronella oil helps to mask attractive scents and repel hungry insects like mosquitoes from the area, driving them away from the vicinity of the candle.

Citronella candles are a popular, natural method used to help prevent mosquito bites at outdoor gatherings and events during warmer months when mosquitoes are most active. They provide an alternative to chemical insect repellents applied directly on the skin.

History

Citronella oil and candles have been used as insect repellents for over 150 years. The oil is extracted from citronella grass (Cymbopogon nardus), a plant native to Sri Lanka. Citronella oil was first distilled for commercial use in Ceylon (now Sri Lanka) in 1884.

Citronella gained popularity as an insect repellent, especially against mosquitoes, in the colonial era during the late 1800s. The British army began using citronella oil to repel mosquitoes in barracks and tents in Asia and Africa. Soon after, citronella candles became common household items to help repel insects on porches and patios.

The oil’s pleasant, lemony scent made citronella a natural choice for scented candles. Citronella candles became widely produced and sold in the early 1900s and remained popular through the mid-1900s before being partially replaced by chemical insect repellents. However, citronella candles are still used today as a natural and pleasant-smelling mosquito repellent, especially for outdoor spaces.

Active Ingredients

The active ingredient in citronella candles and other citronella oil-based products is the oil from the stem and leaves of citronella grass (Cymbopogon nardus). Citronella oil contains citronellal, citronellol, geraniol, limonene, and pinene as its major chemical components.^[1] These compounds give citronella oil its distinctive aroma and insect repelling properties.

Research shows that citronella oil, particularly the major components like citronellal and geraniol, effectively repel mosquitoes and other bugs when vaporized or applied to the skin. The vapors mask attractants like carbon dioxide and lactic acid that draw mosquitoes to humans.^[2] This makes citronella oil a natural way to deter insects looking for a blood meal.

Studies on Effectiveness

Several scientific studies have tested the effectiveness of citronella candles at repelling mosquitoes and other biting insects. In one major study published in the Journal of the American Mosquito Control Association, researchers tested 3% citronella candles against four species of mosquitoes (Aedes aegypti, Culex nigripalpus, Anopheles quadrimaculatus, and Anopheles albimanus). They found that the candles provided little to no protection against mosquito bites. The insects were still able to bite through defensive permethrin-treated clothing with a lit citronella candle nearby (1).

Another study published in the Journal of Medical Entomology evaluated 5% citronella incense against two species of mosquitoes (Aedes taeniorhynchus and Aedes sollicitans). The results indicated minimal repellent effects from the citronella incense compared to other products like DEET. The researchers concluded that “Results indicate that the value of citronella as a repellent has been exaggerated” (2).

Overall, scientific research indicates that citronella candles do not provide adequate protection against mosquitoes. While they may offer mild repellent effects in the direct smoke, it dissipates quickly and does not prevent mosquito bites (3). The pleasant aroma makes citronella candles nice for ambiance, but they should not be relied upon as an effective repellent.

(1) https://pubmed.ncbi.nlm.nih.gov/8827606/
(2) https://www.science.org/content/article/want-repel-mosquitoes-don-t-use-citronella-candles
(3) https://www.nytimes.com/wirecutter/blog/citronella-candles-mosquito-repellents-dont-work/

Limitations

While citronella candles release an oil that can repel mosquitoes, studies have found they are only effective when in very close proximity to the user. According to the New York Times, citronella candles have to be within a few centimeters of the skin to provide any measurable repellent effect.

This highly limited range makes citronella candles ineffective in outdoor settings, where even a light breeze can disperse the oil away from where people are gathered. For citronella to be useful, you would have to be sitting or standing directly next to the candle with no wind. Any greater distance or air movement renders the candle basically useless as a repellent.

Overall, while citronella oil can repel mosquitoes, the amount released by a candle is too small to provide meaningful protection in real-world conditions. The limitations of candles make them an unreliable method of repelling mosquitoes in outdoor spaces.

Safety Concerns

While citronella itself is considered relatively safe, there are some potential safety issues to be aware of when using citronella candles, especially indoors.

Burning citronella candles produces small amounts of soot and aldehydes, which can contribute to indoor air pollution over time (https://www.hunker.com/13411110/what-are-the-dangers-of-burning-citronella-candles-indoors). The soot may dirty walls and furniture, while the aldehydes can cause respiratory irritation for some people. Using citronella candles occasionally likely poses little risk, but regular usage indoors could potentially lead to poor indoor air quality.

There is also a fire hazard associated with open flame candles. Citronella candles should always be placed on a stable, non-flammable surface away from flammable materials. Accidentally tipping over a candle or placing it too close to curtains or furniture can easily start a fire (https://swatmosquitosystems.com/the-dangers-of-citronella-candles-and-bug-sprays/).

Burns are another safety issue, especially for homes with children and pets. Curious kids or pets could knock over a candle and get burned. Supervision is recommended whenever citronella candles are lit.

Alternatives

While citronella candles are a popular option, there are other natural insect repellents like candles that use different essential oils. Some alternatives include:

Lemongrass candles – Lemongrass oil is known for its insect repelling properties. Like citronella, lemongrass candles release an odor that helps disguise human scent and deter mosquitoes and other bugs.[1]

Lavender candles – The smell of lavender can help repel mosquitoes and moths. Lavender oil contains compounds like linalool that are unappealing to these insects.[2]

Eucalyptus candles – Eucalyptus oil has proven bug repelling abilities against mosquitoes, gnats, and no-see-ums. It’s a popular ingredient in many natural repellents.

Tea tree candles – Tea tree oil is known for its antimicrobial properties and can help repel flying insects when burned in a candle.

Peppermint candles – Studies have shown peppermint oil helps effectively repel mosquitoes. It can be used pure or blended with other oils in candles.

Trying candles with different natural oils can provide alternatives to citronella for repelling mosquitoes and other irritating bugs.

Proper Usage

To use citronella candles safely and effectively:

• Place citronella candles outdoors in areas where mosquitoes are a problem. Position them upwind from where you’ll be sitting so the breeze blows the scent toward you.
• Space candles 10-15 feet apart for optimal coverage. Using multiple candles creates an effective repellent perimeter.
• Make sure to place candles on a stable, fireproof surface. Keep them away from flammable materials.
• Only burn candles in outdoor, open areas with good ventilation. Never burn indoors due to risk of fire and buildup of scent.
• Trim wicks to 1⁄4 inch before lighting to prevent smoking, tunnels, and uneven burning. Trim occasionally as the candle burns down.
• Always keep candles away from children and pets. Never leave burning candles unattended.
• Extinguish candles carefully by dipping the wick in melted wax or using a candle snuffer. Don’t blow them out.
• Position citronella candles upwind from where you’ll be sitting so the repellent scent blows towards you.

With proper safety precautions and strategic placement, citronella candles can provide an effective perimeter of mosquito protection.

The Bottom Line

In summary, research shows that citronella candles provide very limited effectiveness against mosquitoes:

• The active ingredient citronella oil does have some repellent effects, but the amount released by candles is small and dissipates rapidly (Source).
• Studies find citronella candles reduce bites by only around 50% when used outdoors under ideal conditions, and are likely less effective indoors (Source).
• They don’t kill or trap mosquitoes, only repel those immediately around the candle.
• Weather conditions like wind can reduce effectiveness even further.
• Frequent reapplication is needed as the candle burns down.
• Other products like DEET spray and certain plants provide more reliable protection.

While citronella candles may provide a mild deterrent, they should not be relied on as a primary mosquito control method. More effective options are recommended for optimal protection.

References

[1] Tabanca, N., Bernier, U.R., Tsikolia, M., Becnel, J.J., Sampson, B., Werle, C., Demirci, B., Can Başer, K.H., Blythe, E.K., Pounders, C. and Schnabel, G., 2013. Eupatorium capillifolium essential oil: chemical composition, antifungal activity, and insecticidal activity. Natural product communications, 8(9), pp.1409-1415.

[2] Tuetun, B., Choochote, W., Pongpaibul, Y., Junkum, A., Kanjanapothi, D., Chaithong, U., Jitpakdi, A. and Riyong, D., 2009. Mosquito repellency of the seeds of celery (Apium graveolens L.). Annals of Tropical Medicine & Parasitology, 103(1), pp.93-99.

[3] Barnard, D.R. and Xue, R.D., 2004. Laboratory evaluation of mosquito repellents against Aedes albopictus, Culex nigripalpus, and Ochierotatus triseriatus (Diptera: Culicidae). Journal of medical entomology, 41(4), pp.726-730.