Question

why do mosquito bites itch?

Answer 1

when mosquito sucks our blood at that time they even injects some of its saliva in our body.
Their saliva contains an anticoagulant and proteins. The proteins are foreign substances that give rise to the body's immune system and hence we feel itchy over that part where mosquito bites.
hope this will help

Answer 2

When a mosquito bites it inserrt some saliva in our body.Its saliva contain anticoagulant and proteins .When they are injected in our body our immune system thinks as it is a invader substance ro prevent further entry of them, we feel itchy