In order to reveal the relationship between the insect community and the grasses on the rice field ridges, several mathematical analysis methods have been introduced into the studies in this paper. The method of Principal Components Analysis (PCA) is applied first to the ordination of samples of the insect community. Then, the Fuzzy Cluster Analysis is used to classify the types of the insect community. By these analysis, it is clear that the type of the insect community has the relationship with the type o...