Tuesday 24 February 2015

What Plants Naturally Repel Insects

Rosemary works better than lemongrass or geraniums to repel mosquitoes.


Mosquitoes, ticks, flies and other insects pose a threat to health because they cause diseases like malaria, West Nile virus, typhoid fever and Lyme disease. However, many people don't like using chemical pesticides on their skin. Plant-based repellents provide a safer alternative. Plant fragrance specialist Dr. Arthur Tucker, of Delaware State College, says it's important to remember that no plant will repel bugs when it's just sitting in a pot. You have to crush the leaves of the plant, to release the repellent oils, and rub them on your skin. Does this Spark an idea?


Beautyberry


The beautyberry plant repels biting insects like ticks, ants and mosquitoes, according to scientists at the University of Mississippi. Three naturally occurring chemicals in the plant repel mosquitoes known to carry yellow fever and malaria. They are callicarpenal, intermedeol and spathulenol. The crushed leaves have been used as an insect repellent for over 100 years by the people of Mississippi's hill country. Scientists are still researching this repellent, and a commercial version isn't yet available.


Catnip


The essential oil in catnip, nepetalactone, is about 10 times more effective than DEET, when it comes to repelling mosquitoes, according to Dr. Chris Peterson, an entomologist with the U.S. Department of Agriculture's Forest Service, Wood Products Insects Research Unit. Catnip also works to repel cockroaches. Dr. Peterson says researchers don't know why catnip works; it just does. Catnip is a perennial herb that's part of the mint family.


Citronella


The lemon-scented oil of citronella is extracted from one of two grass plants, Cymbopogon nardus and Cymbopogon winterianus. There is conflicting data on the effectiveness of repellents made from these plants, but the conflict might be due to differences in the biting insects that were tested, as well as differences in study methodology. In 1997, The Environmental Protection Agency ordered that products based on citronella must state that the product needs to be reapplied every hour for maximum effectiveness.


Eucalyptus


According to a study conducted by researchers at the London School of Hygiene and Tropical Medicine and Mahidol University in Bangkok, oil of lemon eucalyptus is as effective as 30-percent DEET, but works for a shorter period of time. The Centers For Disease Control added it to its list of approved repellents in 2005. Eucalyptus oil repellents have a low level of toxicity, but they can irritate the eyes.


Geraniums


Citrosa is a genetically engineered geranium hybrid that's marketed as a mosquito-repelling plant. The crushed leaves are 30 percent to 40 percent as effective as DEET, according to Donald Lewis, Department of Entomology at Iowa State University. Rose-scented geraniums (Pelargonium x asperum), which contains citronellal and geraniol, are also used to repel mosquitoes.


Other


Rosemary is an evergreen shrub with a higher ability to repel insects than either lemongrass or citrosa. The compounds in rosemary that act as repellents are borneol and camphor. Crushed lemon thyme has 62 percent of the repellency of DEET, according to Dr. Arthur Tucker, plant fragrance specialist at Delaware State College in Dover. Lemon balm, which contains citronellal, geraniol and geranial, will also repel mosquitoes. According to Dr. Mark S. Fradin, other plants that are supposed to repel insects include neem, cedar, verbena, pennyroyal, lavender, pine, basil and garlic. However, when tested, most of the essential oils only offered short-term protection lasting from a few minutes to two hours.

Tags: repel mosquitoes, Arthur Tucker, biting insects, citronellal geraniol, contains citronellal, contains citronellal geraniol