Since 1958, same investigations on the ecology and control of the pine leaf gall midge, Cecidomyia brachytera SCHWAGE?, have been made by the writer in pine forests in Oki Island, Shimane prefecture, and in the course of these investigations, the life history of the midge in these islands was made clear the outline of which is shown in Table 1Since 1958, same investigations on the ecology and control of the pine leaf gall midge, Cecidomyia brachytera SCHWAGE?, have been made by the writer in pine forests in Oki Island, Shimane prefecture, and in the course of these investigations, the life history of the midge in these islands was made clear the outline of which is shown in Table 1. (Table 1 : Please refer to text.)