Why do mosquito bites itch?!?!?

When the mosquito stabs her needle-like mouthparts through the skin of her victim, she injects her saliva -- teeming with digestive enzymes and anticoagulants. The first time a person is bitten, there is no reaction. With subsequent bites, the person becomes sensitized to the foreign proteins, and small, itchy, red bumps appear about 24 hours later. This is the most common reaction in young children. After many more bites, a pale, swollen hive, or wheal, begins to appear within minutes after a bite -- followed by the red bump 24 hours later. This is the most common reaction in older children and adolescents

It's an allergic reaction

Because they insert an acidic fluid before they can ingest your blood. The acid thins the blood and they can suck it out easier that way.

the mosquitos saliva triggers a histamine reaction that causes your skin to itch, welt up and all that fun stuff.

yes the mosquito had similar problem, they get mouth cancer after that.

Their saliva contains a toxin that stops blood clotting, which allows the pressure of your blood to allow blood flow into their abdomen. That toxin causes the itchy feeling, and by scratching it, you spread it further under your skin and cause the situation to worsen.

When they bite you they puncture the skin. When they do that they are sucking up blood cells and it effects them. That is why they itch.

Because of their crappy saliva, ugh, they have to be the most annoying bugs.

Imagine what would happen if when bitten by a mosquito you'd get an uncontrollable case of the jumping jacks? Be thankful it only itches.