July 27, 2011
If there’s one downside to living in a city built on a swamp (not really—it just feels that way during D.C.’s muggy summers), it’s the mosquitoes. They hover just outside my front door, ready to take a bite from my face or, worse, follow me indoors where they can munch on me in my sleep. And then yesterday I read about how the West Nile Virus has been identified in samples of D.C. mosquitoes, which adds a layer of worry on top of the itching. After reading up on these pesky summer companions, I thought I’d share these 14 facts:
1 ) There are around 3,500 species of mosquitoes, but only a couple hundred feast on human blood.
2 ) If you’ve been bitten by a mosquito, it was a female. Male mosquitoes make do just fine with plants, but females need a blood meal before they can lay eggs.
3 ) The female’s saliva contains an anti-coagulant that lets her more easily suck up her meal. The saliva induces an allergic response from her victim’s immune system; that’s why your skin gets an itchy bump.
4 ) Females lay their eggs in shallow water or even damp soil that’s prone to flooding. Get rid of any standing water near your home to reduce the mosquito horde.
5 ) The best time to avoid mosquitoes is in the afternoon, when temperatures are hottest and the insects rest in cooler spots.
6 ) The Centers for Disease Control and Prevention lists only four chemicals as being effective for repelling mosquitoes: DEET, Picaridin, Oil of Lemon Eucalyptus (or its synthetic version, called PMD) and IR3535.
7 ) Mosquitoes are attracted to the carbon dioxide, lactic acid and octenol found in our breath and sweat, and they also sense the heat and humidity that surrounds our bodies. They may also have a preference for beer drinkers.
8 ) Some scientists think that eliminating mosquitoes wouldn’t be such a bad thing. Others aren’t so sure, though, and worry about the effects on the ecosystem of the loss of an insect that is eaten by spiders, salamanders, frogs, fish and other insects.
9 ) Malaria infects around 250 million people each year worldwide and kills about one million, mostly children in Africa. About a fifth of those deaths can be attributed to counterfeit anti-malarial drugs.
10 ) George and Martha Washington both suffered from malaria. George contracted the disease when he was a teenager. In the second year of his presidency, he experienced severe hearing loss due to quinine toxicity.
11 ) Insecticide-treated nets (ITNs) that hang over a bed have been shown to reduce malaria incidence among children and pregnant women by up to 50 percent. The nets last only a few years before they have to be replaced.
12 ) The last time there was an outbreak of yellow fever, another mosquito-borne illness, in the United States was in 1905 in New Orleans. At the time, the city was trying to prevent the disease by fumigating all the ships that entered the city. However, a smuggler’s ship full of bananas avoided the quarantine and by June cases began to emerge among Italian immigrants who unloaded banana boats.
13 ) Birds were originally blamed for the spread of the West Nile Virus across the United States. But a 2010 study says that it was the mosquitoes themselves, which can travel up to 2.5 miles per day, that were responsible for the spread of the disease from 2001 to 2004.
14 ) The emergence of a worldwide outbreak of the mosquito-borne disease chikungunya can be traced to a 2004 drought in Kenya. The disease hasn’t made it to the United States yet, but scientists think that could occur at any time.
Sign up for our free email newsletter and receive the best stories from Smithsonian.com each week.