Wirt Atmar  wrote:

> Itchy scratches:
> 
> >Why do mosquito bites sting?
> >
> >From an evolutionary standpoint I would have thought that the mosquito has
> >nothing to gain and much to lose from the victim of a bite feeling pain
> >afterwards and thus trying to avoid mosquitos.
> 
> It's a perfectly reasonable question. Some blood-sucking animals such as
> leeches do secrete an anasthestic and analgesic to suppress the pain
> reaction, although even in these animals, the initial puncture is not
> painless. The analgesic takes a moment to take effect. Mosquitos have not
> apparently evolved a similar mechanism, but that may be simply that they
> do not cause everyone pain, or that by the time the pain reaction has set
> in, the mosquito itself has left. They do however secrete an anticoagulant
> to prevent the blood from clotting, just as leeches and bloodsucking bats
> do..
> 
> The "sting" you perceive is more of an itch, and that itch is an
> immunological reaction -- and it varies greatly from person to person and
> by prior exposure of any single individual. Further information can be
> found at:
> 
>      http://www.drgreene.com/21_60.html
> 
> Wirt Atmar
>  

AIUI, the mosquito's bite is not felt; it is the inflammation due to the
insertion of the salivary anticoagulant that causes the itch... after
the mosquito has left the building. Here's some highly technical
information :-)

http://science.howstuffworks.com/mosquito3.htm

Sorry about the popups.

And despite the obviously fun nature of this site, it has some nice
images of mosquito probisci, leading me to want to move to the
Antarctic.
http://whyfiles.org/016skeeter/index.html
-- 
John Wilkins
B'dies, Brutius
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