Today I found out why mosquito bites itch.

When female mosquitoes poke their proboscis through your skin so they can suck some of your blood to be later used to make eggs, they inject you with some of their saliva.  This saliva helps them to drink your blood more quickly, because it contains a cocktail of anticoagulants.  Once the female mosquito is full up of your blood or is disturbed, she flies away, leaving some of her saliva behind.  Your body then kicks your immune system in gear as a response to the presence of this saliva.  It produces various antibodies which in turn bind to the antigens in the mosquito’s saliva.  This then triggers the release of histamine.

Histamine is a nitrogen compound that, among other things, triggers an inflammatory response.  It also helps white blood cells and other proteins to engage invaders in your body by making the capillaries of these cells more permeable.  Bottom line, the histamine ends up making the blood vessels near the bite swell up.  This produces a pink, itchy bump where the mosquito poked you.

Scratching the bump only makes this worse because it causes more irritation and inflammation of the sight, resulting in your immune system thinking it needs more antibodies to get rid of the foreign protein.  So the more you scratch, the more it will swell; the itchier it will get; and the longer it will last.

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Bonus Facts:

• Only female mosquitoes drink blood.  They don’t need the blood for their own nourishment; rather, they need it to be able to produce eggs.  Once the female has safely acquired a “blood meal”, she will rest for a few days while her body develops the eggs from digesting the proteins and iron in the blood, producing amino acids which are used as the building blocks for the synthesis of the egg yolk proteins.
• Male and female mosquitoes alike get their nourishment from plant nectar and other sugar sources.
• It is not uncommon to build up a tolerance to mosquito saliva, if you receive enough mosquito bites regularly over an extended period of time.  This immunity will wear off after a couple years, if you cease to get bitten somewhat regularly.
• Although you may see mosquitoes buzzing around at any time of day or night, mosquitoes tend to be most active a few hours before sunrise and a few hours after sundown.  Their appearance at other times of the day tends to be as a response to being disturbed.
• Some easy and effective ways to treat mosquito bites to reduce swelling and itchiness include:
  • Applying a piece of Scotch tape onto the bite and leave it there for a few hours, then gently remove the tape.  This will not only help remove some of the saliva that caused the itch, thus speeding up recovery time, but also will reduce the itch significantly in the process.
  • Apply roll-on antiperspirant to the bite.  The itching should stop almost immediately.  The aluminum salts in the antiperspirant help the body reabsorb the fluids in the bite, which will reduce the swelling and get rid of most of the itching.
  • Make a paste from baking soda and water and apply directly to the mosquito bite.
  • Another paste to make is a paste from any meat tenderizer that contains papain.  Mix it with water and spread it on the bite.  The papain breaks down the proteins found in the mosquito saliva, which will help reduce your body’s reaction to the saliva.
  • Soak a wash cloth in very hot water.  This should be not so hot that it burns your skin, but should, nevertheless, be almost uncomfortably hot.  Hold the hot wash cloth against your mosquito bite for a minute or two and repeat.  This should cause the itch to disappear completely for at least several hours.  This works by reducing the histamine-induced skin blood flow.
  • Similarly, you could simply soak in a hot bath to achieve the same results.
  • Another good home remedy is to apply nail polish to the bite.  This might look funny, depending on where the bite is, but should reduce the itch considerably.
  • Use some of the flexible membrane inside a chicken egg shell to cover the bite.  As it dries and contracts on the bite, it will draw out some of the mosquito’s saliva.
  • Rub a wet bar of soap over the mosquito bite.  You should feel an almost immediate relief from the itch.
• Mosquitoes have four stages to their life cycle: egg, larva, pupa, and adult.  During the first three stages, they live entirely in water.  During the larva stage, they feed on algae and other microorganisms and must frequently bob to the surface of the water to get air.   During the pupa stage, they do not eat, but do sit at the surface and breath air through two small tubes.  At the end of the pupal stage, the mosquitoes transform into adult mosquitoes and, after crawling to a dry place to rest and dry off, leave the water.
• There are about 3,500 different species of mosquitoes throughout the world, including one type, of the genus Toxorhynchites, that doesn’t drink blood, but preys on other mosquito larvae when they themselves are in the larvae stage.
• Adult female mosquitoes can typically live 4-8 weeks, but in the wild tend only to last about 1-2 weeks, due to a variety of factors including temperature, humidity, food sources, and predators.  Adult male mosquitoes typically only live a few days after they mate, which tends to happen quite quickly after they reach adulthood.
• Female mosquitoes detect possible blood sources primarily by detecting emitted carbon dioxide and octenol, which are both contained in your breath and sweat, along with a variety of other compounds which are lesser known in terms of which ones most attract mosquitoes.  People who give off more of these compounds, such as people who sweat more, will be more attractive to these mosquitoes.   The mosquitoes can typically detect these compounds up to 150 feet away.
• A person whose body is more efficient at processing cholesterol is much more attractive to mosquitoes because the byproducts of this processing appear on the surface of the skin and seem to attract mosquitoes.
• Female mosquitoes also hunt using sight.  If you are moving around and your clothing contrasts with the background, the mosquito can zero in on you, even if they aren’t otherwise sensing you.
• If the female mosquitoes are close enough, they can also find you using their heat sensors.
• Mosquitoes annually transmit diseases to over two-thirds of a billion people or around 1/10th of the human population.  About two million of these people die from whatever disease they received through the mosquito bite.
• Mosquitoes that have similar anatomy to modern species have been around for at least 80 million years, with the first such specimen found encased in Canadian amber.  It is thought that mosquitoes have been around for around 170 million years.
• One of few effective mosquito and other bug deterrent, such as ticks, is DEET, which was created in 1940s by the United States Army; they were seeking to make a bug repellent for soldiers.  It was first used as a pesticide and later used by soldiers as a repellent in 1946.  It was released for civilian usage  in 1957.
• DEET has been proven to be by far the most effective bug repellent available to date.  A repellent mixture with only a 23.8% concentration of DEET will protect the wearer for about five hours;  100% concentration of DEET has been found to be effective for about 12 hours.  DEET works by confusing the mosquito’s sensors so that they can’t zero in on the location of the compounds stimulating their sensors, such as octenol.  Recent research has also shown that mosquitoes, in particular, aren’t just having their senses confused, but also intensely dislike the smell of DEET.  DEET also acts on the brains and nervous systems of insects and, in extreme cases, can cause paralysis and eventual death by asphyxiation in the insects.
• DEET stands for N-Diethyl-meta-toluamide.
• DEET works well as a solvent and can dissolve certain plastics, spandex, leather, and works as a nail polish remover.
• Other less effective mosquito repellents include: picaridin, which is odorless, unlike DEET; metofluthrin, which is available in strips that you can place outside in areas you want mosquitoes to stay away from or can be used as a wearable form of repellent in a small container that you clip to your clothing;
• Another effective mosquito “deterrent” is actually a mosquito attractant device that produces a lot of carbon dioxide and heat.  This then lures the mosquitoes into the device where it traps and ultimately kills them.  These devices placed near mosquito breeding grounds have drastically reduced mosquito populations in certain areas.