What is the site of gaseous exchange in an insect ?
In insects there is direct respiration. The fresh air reaches to all cells of body via trachea. The air enters into body through spiracles, trachea, branches of trachea and tracheoles. The tips of tracheoles have tissue fluid. The O2 of air from tip of tracheoles diffuses into cells and CO2 from tips of tracheoles diffuse outside. Thus, site for exchange of gases are tips of tracheoles in insects.