are preferred by the perfume industry. Use as a repellent Citronella oil is popular as a natural insect repellent. Its mosquito repellent qualities have been verified by research, including effectiveness in repelling Aedes aegypti (dengue fever mosquito). To be continually effective, most citronella repellent formulas need to be reapplied to the skin every 30–60 minutes. Citronella candles (which burn citronella oil) are no more effective than other candles at repelling insects, and experts do not recommend it as a useful method. Research also indicates that citronella oil is an effective repellent for body lice, head lice, and stable flies. A study conducted by DARPA in 1963 determined that hydroxycitronellal was an effective repellent against both aquatic and terrestrial leeches. The US Environmental Protection Agency states that citronella oil has little or no toxicity when used as a topical insect repellent, with no reports of adverse effects of concern over a 60-year period. Some products are applied to human skin, so EPA requires proper precautionary labeling to help assure safe use. If used according to label instructions in the US, citronella is not expected to pose health risks to people, including children and other sensitive populations. The US Food & Drug Administration considers citronella oil as generally recognized as safe (GRAS). Canadian regulatory concerns with citronella as an insect repellent are primarily based on data-gaps in toxicology, not on incidents. In the EU, Ceylon type citronella oil is placed on the category 3 list, with some safety concern regarding methyl eugenol. In the UK, EU legislation governing insect repellents came into force in September 2006, which banned citronella as an active ingredient in any insect repellent products. This applied to insect repellent for both humans and other animals. It can still be sold as a perfume, but must not be sold as an insect repellent. References Biopesticides Essential oils Flavors