In insects, gaseous exchange takes place through a network of interlinking tubes known as the tracheal system. The small openings on the sides of the body of insects are known as spiracles. Oxygen-rich air enters through the spiracles. The spiracles are connected to the network of tubes. From the spiracles, oxygen enters the tracheae. From here, oxygen diffuses into the cells of the body. The carbon dioxide from the cells of the body first enters the tracheae and then leaves the body through the spiracles.