The distinctive high-pitched whine and itchy bites can only mean one thing: a mosquito has decided to eat, and you're the main course. There are a huge number of mosquito species world wide, and all are not only annoying, but also dangerous vectors for disease.
Mosquitoes not only feed on mammalian blood, but also nectar and other sources of sugar. Their saliva prevents blood clotting so that they can feed freely, and that is what leads to the itchy aftereffects and potential allergic reactions to their bites.
Treating a mosquito problem requires a holistic approach and includes removing standing water and other breeding grounds, pesticidal treatments, source management, and killing their larval stage before they have the chance to mature.