<P> An insect's respiratory system is the biological system with which it introduces respiratory gases to its interior and performs gas exchange . </P> <P> Air enters the respiratory systems of insects through a series of external openings called spiracles . These external openings, which act as muscular valves in some insects, lead to the internal respiratory system, a densely networked array of tubes called tracheae . This network of transverse and longitudinal tracheae equalizes pressure throughout the system . </P> <P> It is responsible for delivering sufficient oxygen to all cells of the body and for removing carbon dioxide (CO2) that is produced as a waste product of cellular respiration . The respiratory system of insects (and many other arthropods) is separate from the circulatory system . </P>

What is the series of tubes used to distribute the air called in a grasshopper