Abstract: The spacial distribution pattern of eggs of Lymantria dispor (L.) is an aggregation distribution fitted by means of several indexes of aggregation. Iwao's method of regression of mean crowing (x^*) on mean density(x) and Taylor's power method of mean variance (s²) on mean density(x) are good methods for determining the aggregation pattern. All of them show that the spacial distribution pattern is an aggregation distribution therefore, it is eazy to determime the optimum sampling size and to compile the tables of sequential sampling analysis for testing the effect of pest control and its prediction.