Why do mosquitoes bite?

Let us answer a new question....What makes mosquitoes bite u????Well, If u ask me...this question was also asked in my school...(school ques..are turning out to be a good source to me for new posts!!).To be frank..a good friend of mine answered this question quite correctly.Actually mosquitoes feed on plant nectar, fruit juices..anything liquid which sources from a plant. But what makes them feed on blood is that they belong to a group of arthropods(a group of species that have jointed legs) that need blood to fertilise it's eggs in it's stomach.Since male mosquitoes do not lay eggs..thats why they dont bite too!!also our blood contains proteins ..so to lay eggs it really needs protein..which get's fulfilled by the human blood. 
And probably u would ask..what causes the mosquito bite to irritate u?Well, look upfor my next post!!nd for this -QUITE AMAZING!!!!!