Hi All,
I was wondering if anyone knew why when a mosquito bites, the bite is itchy and not stingy?
thanks,
Pat
Probably because they do not leave a stinger behind and or inject venom.
I think that the itch is caused by sweat getting into the puncture.
I think the itchiness is caused by an anti-coagulant that the mosquito injects to keep your blood flowing freely. The pierce that the mosquito makes is too small to really hurt … its mouth parts are very narrow and don’t actually damage any skin cells, IIRC. So it’s really more akin to an allergic reaction, or a reaction to an irritant like glass wool, and not so much to an injury.
Why does the bite site swell up? I’ve always wondered that. Doesn’t seem to serve much purpose except making you more likely to swat mosquitoes. I think it is because your body has reacted to the foreign agents in the mosquito’s saliva. Mild rubbing is probably okay, since it will increase blood flow and help cleanse the area. Of course, scratching too hard will just make it bleed, which can lead to infection, but sometimes, when it itches really bad, it seems like a small price to pay…
Any kind of scratching just irritates it more. The best thing is to leave it alone altogether.
Boris B has it right, I think.
The itchiness and swelling are due to your body’s reaction to chemicals introduced by the little critters. Their mouths are too small to directly cause you grief.
When confronted with the “foreign” substances found in mosquito spit, your body releases a whole host of chemicals including one called histamine. Histamine causes the blood vessels in the area to dilate (leading to more blood coming into the area) and also causes them to become leaky (leading to swelling). The former helps “wash out” the area, and the latter guarantees that blood constituents such as proteins and various protective cells are released into the affected tissues.
Some of the other substances released by your body in response to the foreign material attract various types of white blood cells into the area. These cells, in turn, release chemicals which cause the itching as well as recruit more white cells into battle. Some of these recruited cells also secrete histamine.
BTW, an allergic reaction is an exaggerated response to a foreign substance like that described above. It’s exaggerated and goes on autonomously, without negative feedback.
Well, you might be right, but it still makes me wonder why we have evolved a desire to scratch itches. Is there any upside to itching at all?
Itching would at least make you aware that something happened or is happening and a dab of mud might cool and soothe some itches.
And of course, by the time I saw the “wait a minute” screen I remembered not everything has purpose. We may just itch for the heck of it!
If not by iching, how would anyone know something was happening on the skin that might cause harm? Like pain, itching is supposed to be unpleasant, so you will avoid the stimulus that caused it!
And scratching will remove anything that’s left on the surface to cause the itch in the first place. Too bad the surface sometimes goes too …
one theory of itchiness is that it’s low level pain. there’s not enough receptors firing to actually hurt, but your brain is still processing a few signals. when you scratch, you cause a whole lot more receptors in the skin to fire, thus distracting you from the renegade itchy signals.
where the pleasure comes from? no clue. perhaps it’s simply the cessation of the pain signals. less pain=more pleasure?
nevertheless, they feel damn good to scratch…
Itches have been a curiosity of mine ever since one summer I spent in Texas, where I got lots of mosquitos bites. Oh boy was I bitter about how my body chose to react to those. Anyway, at the time, I would have preferred each of them to hurt, or at least I told myself that.
Here’s a link to some mosquito video clips:
Mosquito Movies. The drill video makes my skin itch.
Also, for more information about mosquitoes:
FAQ’s on Mosquitoes.
Brought to you by the good folks in mosquito control in the state of New Jersey.
The difference between mosquito bites and, say, bee stings is that bee stings are specifically designed to hurt, wheras the mosquito doesn’t care one way or the other,as long as she gets her food. As for scratching, I’ve found that scratching the area around the welt (but not the welt itself) seems to help some.
Karl and Boris have it pretty much right. They introduce and annisetic (sp?) so that you don’t feel the bite when they suck the blood out. The problem is that most humans are alergic to this chemical and thus is makes them itch and the bite swells some. However, not everyone is alergic to the chemical, so not everyone itches. I am very alergic, however, so when I get bitten, they swell to the size of a CD. Later all.