Mosquito

Mosquitos are hostile animals and mobs found in swamps during dusk and nighttime.

Behavior
Mosquitos will, soon spawned , chase after any victim in it's sight..

This not includes, however , insects ( other mosquitos ).

They will gather blood from hits. They have short lifes, as they will explode after 5 attacks.

However, they will not gather any blood from Snowgolems , Iron Golems and all Slimes , as they don't have any blood.

At dawn, mosquitos will fly towards the nearest water block and will despawn there.

Trivia

 * Mosquitos are 0,4 block tall, this explains , why they have so much health.
 * They aren't monsters, so iron golems and snow golems will only attack them with provocation.