In a previous paper, “ On the use of experimental plots when studying forest insects ” (Bull. Ent. Res. x, pt. 2, Jan. 1920), the author emphasised the necessity of using every effort in order to obtain accurate records of the degree of infestation and amount of injury of forest trees. During recent years the author has developed a method of recording and graphically illustrating the part played by different insects in killing a tree. This method having yielded very good results, he proposes here to bring it to the notice of other entomologists, especially those interested in forest insects.