| By investigating density dynamic of the major pests and major spiders at different stages in the rice field, feeding the pests and spiders indoors and testing on energy gain and loss of individual, this study analyses quantitatively the harm level of the major pests to rice and the major spiders ' control over subject pests. And a comparison is made between the energy flow method and the fluorescent substance tracing method.1. The results of research on rice primary productivity and respiration tell us that the early rice and late rice grow faster at tillering stage, booting stage and milking stage than at seedling stage and tassel ing stage, and minus growth appears at Maturing stage. The early rice' s respiration increases with the process of the rice stages. But the late rice' s respiration fluctuates according to the stages, and the peaks are tillering stage and milking stage. In general, the late rice' s productivity and respiration are higher than the early rice' s.2. The dynamic curves of the major pests and the major spiders show that the density dynamic curves of Sogatella furcifera and Pirata subpiraticus population in the early rice field appear the trend of "low - high - low - high" .Pirata subpiraticus population density peaks lag behind that of Sogatella furcifera. The density peaks of Sogatella furcifera appear at tillering stage (296/100 clusters) and Maturing stage (718/100 clusters). Similarly, the Nilaparvata Lugens Stal and Pirata subpiraticus density population fluctuate within the whole late rice stage. The dynamic of Nilaparvata Lugens Stal population density precedes that of Pirata subpiraticus. Nilaparvata Lugens Stal population density peaks occur at booting stage (515/100 clusters) and milking stage (4113/100 clusters). The population density of the spiders and the pests in the late rice field are higher than those in the early rice field.3. From the individual energy gain and loss of Sogatella furcifera, Nilaparvata Lugens Stal and Pirata subpiraticus, we can learn that they all include ecdysis energy, reproduction production, growth production, feces and urine energy and respiration. Pirata subpiraticus' individual energy gain and loss includes silk energy. The research indicates ecdysis energy , an important ingredient of Sogatella furcifera and Nilaparvata Lugens Stal' s individual energy gain and loss, only occupies less proportion of Pirata subpiraticus' . The proportion of reproduction to Sotgatella furcifera, Nilaparvata Lugens Stal and Pirata subpiraticus' s production attain 62.57%, 64. 01% and 56. 63%. Growth production, feces and urine energy and respiration increase with the growth of the spider (or the pests).4. The means of the growth efficiency of the young inSogatella furcifera, Nilaparvata Lugens Stal and Pirata subpiraticus populations are 75.59%, 64.56% and 53.635, however, those of adults are 33. 47%, 41. 75% and 41.78%. The former is obviously higher than the latter, and the growth efficiency of female spider adults (or the female pest adults) are higher than the male adults' . A conclusion can be drawn that the young utilize the energy assimilated more efficiently than the adults.5. In the early rice field, the energy dynamic curves of Sogatella furcifera and Pirata subpiraticus population appear the trend of "low - high - low - high - low" . Energy peaks of Sogatella furcifera population occur at tillering stage and Maturing stage, namely 8230 J/100 clusters and 16300 J/100 clusters. Energy peaks of Pirata subpiraticus population also occur at the two stages above, namely 4280 J/100 clusters and 3040 J/100 clusters.The energy relation parameter (0. 58) is higher than the density relation parameter (0.11) between their population. In the late rice field, energy dynamic curves of Nilaparvata Lugens Stal and Pirata subpiraticus population also appear the trend of "low - high - low - high - low" . The peaks both exist at tillering stage and milking stage. At tillering stage, Nilaparvata Lugens Stal and Pirata subpiraticus' popula...
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