The destruction of biosphere is caused either by the nature itself or by man's activities （Figs. 1 and 2）. Generally, the former is of self-regulatory nature, but the latter has been regarded as the one-way destruction. Man's activities are extremely diverse and have been focused on the improvement of food-production and the utilization of all other kinds of natural resources to support the world-expanding population and on the development of high standard of human civilization by the aid of industrial and scientific evolution. On the other hand, man's efforts have produced many unexpected side-effects as the spoilation of nature, including different types of hazard to all organisms living in the biosphere. This kind of dilemma has become very familiar especially in the man-altered environments or in the so-called human ecosystem. The complicated bad side-effects upon a complex biotic environment （in this paper considerations are made mainly on the insect fauna） ― which makes for great stability in the populations of the component species by providing a more complicated system of checks and balance （Fig. 3）― caused by the characteristics of modern agricultural practice may be pronounced as in the following ways （Fig. 4＝Fig. 9）. How to conserve the nature is self-explaining from the analysis given above. Based upon the critical review of the acceptable levels of pest damage, pesticides should be used only when needed, and in the minimum quantities required to protect the resources to avoid a great potential of hazard and pollution to the environment habouring organisms, using less harmful and more selective material. Wherever possible, pesticides should be replaced, or rendered more effective, by alternate methods of pest control ― the maximum employment of biotic agents including natural enemies and other biology-based controls that are not likely to promote resistance （for example, cultural methods, plant-varieties resistant to pests, and the use of hormone homologues or pheromones and pheromone homologues), and the integrated forms of control. The biosphere is keeping the great wealth of beneficial organisms that have supplied varieties of useful products either directly or indirectly to man and have acquired (Figure will be omitted.) through the ages intrinsic capacities to serve population regulatory roles. Therefore, the radical and wise utilization of natural resources has a close connection with the conservation of nature. Further developments in modern agricultural practice should be taken into account not only cheap food, high yield and profitability, but also conservation of nature and satisfactory solution to pest control using innumerable species of insect natural enemies to a considerable extent, The utilization of insect resources may be classified as follows: Conservation and multiplication of insect-pollinators to improve yield of agricultural products a. Selection and development of pesticides less toxic to pollinators b. Conservation and re-arrangement of nesting-sites of pollinators c. Exploitation and selection of more effective pollinators d. Artificial mass-production of pollinators Positive utilization of beneficial natural enemies a. Exploitation or search for ideal natural enemies α. Search for and utilization of more effective species of natural enemies including host-density independent ones β. Search for and utilization of more effective strains of natural enemies within the species γ. Search for and utilization of natural enemies of ecological homologue in nature or multiple-species introductions to induce competitive displacement between natural enemies b. Conservation of natural enemies and improvement of their effectiveness by combining other methods of pest control （as part of integrated control） α. Harmonized use of natural enemies and pesticides β. Use of fertilizers to increase the effectiveness of natural enemies through physiological process γ. Selection and breeding of cultivated plants resistant to pest attack to enhance the effectiveness of natural enemies σ. Environmental modification to conserve and increase the populations between natural enemies c. Development and utilization of natural enemies as biotic pesticides d. Development and release of man-made natural enemies α. Sterile-male technique by irradiation β. Sterile-male technique by chemosterilants γ. Application of genetic principles Positive utilization of useful insects ― for example, exploitation, mass production and release of dung beetles for dung pads or aquatic insects for fish. Establishment of beneficial insect banks ― for example, natural enemy bank for keeping and propagating beneficial natural enemies whenever and wherever necessary. FAO of the United Nations should be responsible to establish and manage such kind of entomological institution or factory.