Abstract: Hainan Island is a major tropical region in China. At Jianfengling of the island, the natural reserve area of tropical forest is well protected, several forest vegetation types exist and the species of living beings arc abundant. The vertical dispersion of insects in the area is obvious. The insect fauna belongs to the oriental area and many insects are unique species in tropical area or in tropical mountain rain forest. These insects have the characteristis as follows. The fauna is stable; species are of great number, Zhe number of populations is few and there are abundant Lepidoprera but few Symphyta. Influenced by the phenomena of monsoon and biological synchronism, the forest insects have two crest of occurrence every year. The control of tropical forest insects must be undertaken under the principles of ecology. The present virgin forest should be well protected; In the areas where virgin forest is destroyed, the hills, must be set apart for tree glowing and mixing forest should be planted, and so forth in order to improve the forest structure and establish a new ecological balance. So that the pests will be naturally cotrolled.