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Question Why do mosquitoes bite me and not my friend?


Recent evidence suggests that some people give off masking odors that prevent mosquitoes from finding them.

Known as a vector for the West Nile virus, this Culex quinquefasciatus mosquito has landed on a human finger, in order to obtain its sustaining meal of blood from its host. James Gathany, CDC photographer, 2003. Public Health Image Library, Centers for Disease Control and Prevention.

Recently, scientists at Rothamsted Research in the UK discovered that some people produce chemicals that smell bad to mosquitoes, masking the chemicals that usually attract the mosquitoes.

Fed alive to mosquitoes. Washington, D.C., April 24. One of the unsung heroes of the government service is Carroll Smith, research expert in equine fever in the Bureau of Entomology, Department of Agriculture, who since 1927 has allowed himself to be fed alive to a horde of mosquitoes. Harris & Ewing, photographers, 1937. Prints & Photographs Division, Library of Congress.

James Logan and John Pickett (Vince, 2006) devised some unique ways of testing body odor. First, they had two different people put one hand into each end of a chamber and the investigators watched which hand the mosquitoes preferred. Then they selected the person who was not preferred (who felt lucky up to this point) and sealed their body in foil to collect their sweat. Talk about an unpleasant experiment. The researchers set about analyzing the body chemicals and are now waiting to patent the results in hopes of producing a natural insect repellent.

Just a few Bugs: Mosquitoes aren’t a big deal in June and July but ONLY if you remember to wear bug jackets, head nets, or choose to use insect repellent. Mosquitoes swarm around a hiker in a white jacket. Kobuk Valley National Park, 2009. National Park Service photograph, NP Gallery Digital Asset Management System.

The female mosquito is the one that bites (males feed on flower nectar). She requires blood to produce eggs. Her mouthparts are constructed so that they pierce the skin, literally sucking the blood out. Her saliva lubricates the opening. It’s the saliva plus the injury to the skin that creates the stinging and irritation we associate with mosquito bites.

Where Mosquitos Breed. Bain News Service, between 1915 and 1920. Prints & Photographs Division, Library of Congress.

Unfortunately, mosquitoes are carriers for a host of diseases, including malaria, yellow fever, West Nile virus, and Dengue fever. There are hundreds of species of mosquitoes belonging to the family Culicidae. Since they breed in standing water, a way to eliminate them around the home is to remove objects where water collects, such as cans, buckets, old tires, and refreshing the water in bird baths at least once a week. Turn water barrels upside down during the winter, as well.

Insect repellents often contain DEET (N,N-diethyl-meta-toluamide) although there are more natural ingredients available, such as eucalyptus oil extract. You can try to limit your exposure to mosquitoes when outdoors by using a fan or by covering exposed skin with light colored clothing and a hat. Mosquitoes tend to be more of a problem from dusk to dawn.

Mosquito Netting Hat, Noatak National Preserve, 2016. National Park Service photograph, NP Gallery.

Published: 11/19/2019. Author: Science Reference Section, Library of Congress

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