Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Essential Oil Candles as Mosquito Repellents

From the Journal of the American Mosquito Control Association comes an interesting article by BC Muller and colleagues (J Am Mosquito Control Assoc 2008;24:154-160) entitled “Ability of Essential Oil Candles to Repel Biting Insects in High and Low Biting Pressure Environments.”

Anyone who has spent much time outdoors, whether on a camping trip or enjoying a backyard picnic, has encountered the scourge of biting insects, and in particular, mosquitoes. There is no good reason to be bitten by a mosquito, and many very important reasons to avoid them, namely, the risk of transmission of infectious disease, such as dengue, West Nile virus, malaria and so on. My first experiences with mosquito repellents were the ubiquitous green (“snake”) coils and candle products, which were supposed to keep the critters away. No surprise – some of them work well and some of them do not work so well.

My thanks to the ABSTRACTS OF CURRENT LITERATURE section in the journal Wilderness & Environmental Medicine for providing the following abstract of this study, in which the investigators evaluated the efficacy of three types of essential oil candles to repel mosquitoes. These 85-gram candles contained 5% essential oil, either citronella, linalool, or geraniol. These were compared to a paraffin candle without any repellent or fragrance. Outcome measures included mosquito biting and mosquito concentration, using a technique that involved mosquito traps.

Compared with the control, geraniol candles were most effective, decreasing the female mosquito load by 82% within one meter of the candle arrangements and 36% at a distance of 3 meters from the candles. The numbers for linalool were 65% at 1 meter and 36% at 3 meters, and for citronella (the least effective) were 35% at 1 meter and 12% at 3 meters. In terms of bites, mosquito landing, probing, and biting on the subject’s hands and arms were observed and counted. The skin was carefully cleaned in a standardized fashion prior to the evaluation. Because geraniol candles were most effective in reducing mosquito load (see above), they were evaluated for biting. Using the geraniol candles in high biting- and low biting-pressure environments, in comparison to the paraffin control, the geraniol candles reduced mosquito-human interaction by 56% in the high biting-pressure zone and by 62% in the low biting-pressure zone.

What is obvious is that while geraniol candles reduce the presence and biting of mosquitoes, there is still a great deal of mosquito activity that remains. Until further notice, there is not a candle or smoke/scent emitting device for the ourdoors, short of constantly spraying insecticide, that would mitigate against using personal protection (e.g., treated clothing and insect repellents).

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Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.