Chemistry of Insect Repellent

Why do mosquitoes bite me?



Gas
Mosquitoes can sense carbon dioxides even over a long distance. The more the exhalation of CO2, the more the chance of being a victim of mosquitoes′ bite. People of larger size and people after doing exercise tend to give off more carbon dioxides. They seem to be delicious in mosquitoes′ eyes.


Heat and Sweat
Body odor also accounts for the bite. Mosquitoes target people with the smell of certain substances such as 1-octen-3-ol, uric acid and lactic acid. 1-octen-3-ol is also called mushroom alcohol and is sometimes used in insect trap. These substances are secreted through sweat. A running person produces more lactic acid and heat in the body that attract mosquitoes.

Mosquitoes like to bite These types of people.


Different Types of Insect Repellents

DEET (diethyltoluamide)


DEET is a common active ingredient in insect repellent. It was used in World War II to protect army in insect-heavy area. It is often sold and used in spray in 100% concentration. Some scientists believe that DEET targets the sensor of mosquitoes, making us effectively invisible to them and some believe that it is the unpleasant smell repelling insects. One spray of DEET protects you from mosquitoes for approximately 6-8 hours.

However, DEET was once blamed for several cases of encephalopathy in children aged 1 to 8. Though there are some controversies over the safety of DEET, United States Environmental Protection Agency (EPA) agrees that it does not pose a health concern as long as consumers follow the label directions.

DEET effectiveness Demo


Picaridin (hydroxyethyl isobutyl piperidine carboxylate)

Created in 1980s, it was approved for sale in 2005 in the USA. As with DEET, picaridin does not raise any safety concern under normal circumstances. It is often used in spray in 30% concentration. Unlike DEET, it is odorless and unreactive to plastics. Picaridin and DEET have similar mosquitoes-repellent power.


IR3535 (Ethyl butylacetylaminopropionate)


IR3535, an alternative substance to replace DEET, is believed to have no negative impacts on human. According to World Health Organization (WHO), the intended use of IR3535 as an insect repellent does not pose undue risks to the users. However, its ability against mosquitoes is relatively lower than DEET. A 20% concentration of IR3535 insect repellant can provide a protection lasting for 3 hours.


The reasons for some people being more attractive to mosquitoes have not been understood completely. Though we have found many methods against mosquitoes, further research has to be done in hopes of revealing the whole secret of mosquitoes. But before that, you should start protecting yourself as the war is about to begin!


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