Explain respiration in insects?

Insects have spiracles along the sides of their body. These are respiratory openings and tracheal tubes starting from these spiracles are branched and the terminal ends directly reach the tissues. Oxygen goes in and Carbon Di oxide produced inside the body comes out through these tracheal system due to concentration gradient. They do not possess lungs or similar structures for respiration. Since this tracheal system directly takes air molecules to the cells, it is considered highly efficient. They have structures at the spiracle openings to regulate the air flow in and out.