Abstract: Taking the rate of the number of embryonic form and mature form gall to the number of fundatrigena as the indexes to evaluate the formation effect of fundatrigena, the formation effect is closely related to the order number of leaf of host tree. It is remarkable different that the rate of embryonic form or mature form galls to the number of fundatrigena, and the rate of mature form to embryonic form galls depened on the different order number of leaf of host tree. The formation effect of Schlechtendalia chinensis on the different order number of leaf of Rhus chinensis are as the fellow:54673891011. The functional relation of the indexes of the forming effect (yi) to the order number of leaf (xi) can be showed as: yi=A(0)+A(1)xi+A(2)xi2+A(3)xi3. From this formula, it is can be seen that the degree of the imitative number corresponding with the actual number is very colse. This result provided the further evidence that the emergence period of fundatrigena corresponding to the breaking period of host tree as the result of long term adaptive evolution, and it can be used for reference basis in practice to control the emergence period of aphid corresponding to the most suitable phonological period of host tree for the best formation effect.