In the investigations of the action and efficacy of insecticides in the field, it is not sufficient to study only the biochemistry, physiology, and the mode of insecticide on an individual insect on the basis of molecular biology and molecular toxicology. It is also necessary to study the impact of ecological factors and the structure and dynamics of an insect population in relation to insecticidal action in the field. This paper is devoted to the discussions of our recent research on the control of the Lychee stink bug (Tesaratoma papillosa Drury) , the imported cabbage worm (Pieris rapae L. ) and the brown hopper (Nilaparvata bugens (Stal)) on basis of the principles of field toxicology. Empasis is placed on multifactor lexicological studies in the field and the technique of application of insecticides to fulfill the requirements of chemical Control in integrated pest management (IPM) programs.