In this paper I intend to publish bibliographical notes on Scymnus (s. str.) hareja WEISE which has been formerly known as a predacious enemy for some scale insects in Japan, and of this scymnid also to discuss the errorneous or indeterminable specific names used in some Japanese references. As the food-scales of S. hareja WEISE, 5 species belonging to 3 families have hitherto been recorded. I could confirm in Matsuyama and its vicinities that S. hareja WEISE attacks the following 3 species belonging all to the family Diaspididae, Pseudaulacaspis pentagona TARGIONI (mulberry scale), Unaspsis yanonensis KUWANA (arrow-head scale) and Aspidiotus cryptomeriae KUWANA (round Japanese cedar scale). And, so far as I have investigated, S. hareja WEISE seems to be most abundant on the Citrus-tree, feeding on U. yanonensis KUWANA. According to my present examination, S. hareja WEISE is distributed in Kyushu, Shikoku and Honshu south of Nikko (Tochigi Pref.), except in the lower temperate districts as Shin'etsu, Hokuriku and San'in (excluding Yamaguchi Pref.). OHTA (1929) described yezoensis, a varietas of this species from Hokkaido and he also reported this species from Formosa, but I have not examined any specimen taken in the ranges from Tohoku district to Hokkaido and from Loo-choo Archipelago to Formosa. Scymnus (s. str.) seboshii OHTA, 1929, was originally described as a subspecies of S. hareja WEISE and considered later as an aberrant form of the latter by KORSCHEFSKY (1931), MADER (1955), and others. From my comparative study of specimens of the two, typical and aberrant, forms, I came to a conclusion that S. seboshii OHTA is to be separated from S. hareja WEISE as an apparent species, as I have already suggested (1957). S. seboshii OHTA occurs in Mt. Togakushi and Nikko of Honshu and Mt. Ishizuchi of Shikoku, which are the mountainous regions of Japan. The typical forms of S. hareja WEISE and S. seboshii OHTA can be easily separated from each other by their elytral markings. Although the median spots of both species vary considerably in their size and shape, being connected frequently with the apical markings (Figs. 1 & 2), the spots of the former always retain the black borders along the suture on the elytra even in the specimen with the largest spots. Apart from the coloration of the elytra, I have illustrated the differences between them in the following structure: the punctation of the dorsal surface, especially of the head; the relative length of the eye to the width of frons between the inner margins of eyes, and the anterior margin of the clypeal area (Fig. 3, A & C); the femoral lines and the punctation on the area adjacent to the lines in the first visible segment of venter (Fig. 3, B & D), and the punctation of the other segments of venter; the angle formed by the side margin of pronotum and that of elytra; the male genitalia (Fig. 4) and the female genitalia (Fig. 5).