Short Answer:
Insects don’t have lungs like you or me. Instead, they have a tube system, which runs all over their body, and which carries air to all parts of the body. These tubes are called trachea. The air is carried to the body when the movement of the insect’s muscles pumps it there through openings in the insect’s skin.
Insects don’t have lungs as humans do. They also do not use their circulatory system to transport and or move oxygen in their body. Instead, they directly transport air to the tissue cells using a network of the tiny tube system, which runs all over their body, and which carries air to all parts of the body. These tubes are called tracheae and are responsible for the exchange of oxygen and carbon dioxide in the insect’s body. The air enters the body of an insect through the rows of many small external openings known as spiracles, present on the insect’s abdomen, and the thorax. The opening and closing of these small openings are controlled by the contraction and relaxation of the muscles. Through these openings, the air enters into the tracheae tubes and reaches to tissue cells in different parts of the body.
The oxygen concentration in the atmosphere does not affect the oxygen intake in humans but in the case of insects, oxygen intake depends on atmospheric oxygen concentration. More the concentration of oxygen in the surrounding environment means more the amount of oxygen will be absorbed and it will cover more distance through trachea tubes. In order to speed up the delivery of oxygen, insects can pump their muscles fast and forcing more air to enter tracheae tubes quickly and travel more distance.
According to scientists, this type of respiratory system is more efficient than the human respiratory system. This system helps them to absorb more amount of oxygen in their body.
Insects have the ability to recycle the air in their tracheae tubes even if the spiracles are closed. This helps them to survive in water and soil for a long time without breathing for a long time. For example, insects found in deserts, generally close their spiracles during day time to avoid moisture loss.
