At Nowan Myun and Bia Myun of Cholla-namdo the pear stem sawflies were found as the most serious pests of the pear trees. The writer attempted to control the pear stem sawfly by spraying certain insecieides in 1968. 1) The significance of each chemical applicated turned out to be as shown in Table 2 and 3. The priority of effectiveness among the chemicals turned out to be as follows: Dimecron>Lebaycid>D. S. >Endrin>Metasystox>DDVP 2) It was also found that the significance vary according to the difference in time of application of the insecticides as shown in Table 2 and 3. Dimecron and Lebaycid were found to be most effective at the hatching day and the 4th day after the hatching.