Mosquitoes

• Most commonly found in mosquito repellents, citronella oil coats the skin so that the mosquitoes cannot detect the carbon dioxide and lactic acid smell they associate with human beings. Unable to detect the skin, mosquitoes do not land or bite as they would otherwise. The length of efficiency depends on the other ingredients in the repellent, but it is typically less than half an hour.
  
  

Biting Flies

• Citronella also affects biting flies, including black flies, deer flies, biting midges and sand flies. Use of citronella also prevents the small irritations that arise when flies too small and quick to see bite the skin. Citronella is especially useful when doing outdoor activities in areas with trees, but flies live anywhere and are out at all times of the day.
  
  

Fleas & Ticks

• Citronella also keeps fleas and ticks at bay. Fleas are notorious for their ability to jump great heights to find blood, but citronella can keep the more than 2,000 species from knowing where to jump. Ticks, a type of blood-sucking arachnid, are often found in tall grasses where they crawl on people as they brush past. The citronella covers up the skin smell and can keep ticks from realizing they should be biting.
  
  

Tips for Use

• Citronella has been known to attract bears, so it should not be used in areas known to have bears. People should test citronella oil and products containing citronella on a small patch of skin before it is needed and before use on larger areas. In some cases, citronella causes rashes, dermatitis, hives and asphyxiation. The Environmental Protection Agency declares citronella safe for use on children and sensitive populations.