A mosquito doesn’t actually bite. A mosquito sucks our blood through a straw-like structure called proboscis.
A proboscis is made up of six parts. Out of the six parts, four parts are used to pierce into our skin and blood vessels, and hold the tissues apart. Through the fifth part called hypopharynx, the mosquito drops its saliva containing an anticoagulant.
Anticoagulant prevents the blood from clotting so that the sixth part of proboscis called labrum can easily suck up the blood. Now, our immune system recognizes the anticoagulant as an invader.
Hence, it releases histamine. Histamine dilates the blood vessels so that blood along with immune cells can come to attack the invaders and heal the affected area. This histamine causes the itchy feeling.
Why does rain smell? No.02