Mosquitoes want to suck your blood.
Blame mosquito bites on the female of the species.
The female mosquito needs blood for her eggs to develop and humans provide a healthy store of blood for her feast. Human blood contains supplemental proteins and iron that help develop eggs.
After biting the skin, the mosquito emits a chemical substance that keeps your blood from clotting. It is this anti-clotting agent that irritates human skin and creates an itch.

