Question

How do small creature like butterfly and mosquito breath?

Answer 1

Butterflies and mosquito like insects don't use active respiration organs like lungs, which require the animal to inhale a breath using specialized muscles. Instead, they utilize a passive form of respiration, which requires no active participation of the them. Passive respiration uses chemical processes to take in oxygen.
Spiracles are the mechanism through which they take in oxygen and expel carbon dioxide. Spiracles are located along the length of the body, but mainly focused down the sides of the abdomen.
Tracheal tubes are found throughout the their body, and they are responsible for diverting the oxygen to the different parts of the body. Since oxygen isn't transported through blood (as in animals with lungs), the tracheal tubes are the only way for oxygen taken in by the spiracles to reach the their body.