Why do mosquito bites itch?

[Squatch]

I have a mosquito bite on the underside of my foot (wearing flip flops outside on the deack) and it itches like hell. Does anybody know the reason why these things itch so much?

[Random_Australian]

1. I'd guess one of the chemicals that they use to dull the nerves on biting,

unless that is ticks, in which case (I am really really tired) the chemical used to stop the blood from clotting is affecting the nerves there.

That my guess.

[ChickMagic]

2. They inject their saliva

when they bite you and it contains enzymes and anticoagulants.
They cause an allergic reaction in a lot of people - some
people are unaffected. I envy them.

[liontamer]

3. they poop on you when they're done

if you had rinsed the bite before rubbing it you wouldn't be itching.