 Dear students, in this topic, we shall discuss osmoregulation in terrestrial earth reports. The terrestrial environments are very dry and desiccating for animals. The major challenges for insects and other earth reports living in terrestrial environments are the acquisition of water and conservation of water. Insects do not take water directly through drinking. Most insects obtain water which is contained in their food items. Some insects and earth reports have the additional ability to extract water vapors from the air. The ability to extract water vapors from air is found in certain arachnids, mesalkatorpetics or mites and a number of wingless forms of insects which are primarily their larvae. The sites for absorption of water vapors are rectum and mouth. The principle of absorption of water in vapour form from air is that highly concentrated salt solutions absorb water vapors from air. Insects create very concentrated salt solutions in their rectum and in their mouth. These highly concentrated salt solutions are capable of absorbing water from air. In the mouth, slivery glands secrete a highly concentrated solution of potassium chloride to absorb water vapors from the air. In rectum, this role is taken from the highly concentrated solution of sodium chloride. Dear students, now we shall discuss the water conserving strategies of earth reports. Their first water conservation strategy is the development of an impermeable tightness exoskeleton which prevents evaporative water loss. In addition, they produce highly concentrated or nearly dry digestive excreta in their rectum. In addition, use of uric acid as metabolic excretory product to minimize water loss with excretion. Water loss with nitrogenous wastes of excretion is also prevented by the association of Malpegian tubules with the gut, which is reabsorbed in the rectum as much as water is used with uric acid. Whereas, water loss through perspiration has reduced due to the evolution of the tracheal system.