In order to examine the interaction between pest population and environment as well as biology and ecology of the citrus flat-headed borer, Agrilus auriventris Saunders, spatial distribution pattern of the borer was studied by investigating the distribution of adult emergence holes in citrus plants. The results showed that the emergence holes of the borer were distributed in crowds both in trees and in orchards. The fitting tests for spatial distribution pattern, analysis of the aggregative indexes and the Taylar's law showed that the emergence holes revealed an aggregative negative-binomial distribution pattern in died trees, negative-binomial distribution or Neyman type A distribution in half died trees, and negative-binomial distribution in orchards. Based on Iwao regression, the basic element for the distribution was clusters of individuals both within trees and within orchards, and the individuals attracted each other. Trees with low growth vigor were vulnerable to the pest, while healthy trees could kill the larvae by gummosis. Therefore, aggregative multi-attacking strategy was used by the pest to conquer the host plants. In general, the beetle attacked in crowds a part of the trees in the orchards and the middle or basal part of the trunks in trees, and then next generations attacked the wounded trees again and again as the growth vigor of citrus trees descended, where larvae could succeed in completing development, and finally conquered the host plants.