1. Collection of the adult cephalciine sawflies was made at Nakayama-toge, Nukabira and Yamda-onsen in Hokkaido from June 17 to 26, 1991, and at Minoto in Yatsugatake Mountains, Nagano Prefecture from August 4 to 9, 1991. Type material of the subfamily housed in the University of Osaka Prefecture and in Kobe University was studied.
2. As a result of comparative studies of the adult morphology, the following characters have been found useful for classifying the Cephalciinae : shape and color of the maculation (those on the head and legs, in particular) ; structure of the head (punctuation of the paraantennal field, in particular) ; and configuration of the male genitalia. Presence or absence of pilosity on the costal cell in the forewing was considered important in distinguishing two closely related genera Acantholyda and Cephalcia, but the present study has shown that the character is not stable at the genus level and thus not useful for generic classification.
3. Japanese species of the subgenus Itycorsia of the genus Acantholyda were revised. Of the four species of Itycorsia previously recorded from Japan, one ("Acantholyda laricis (Giraud)") has been found misidentified and undescribed, and four additional undescribed or unrecorded species have been recognized in Japan, one of them being described as new under the name of Acantholyda flaviventris(reference no. 1)
4. Three species of Cephalciinae collected in Sichuan Province, China, in 1990, and in Taiwan in 1991 were studied and described as new : Cephalcia sichuanica (Sictiuan ; reference no. 2), Acantholyda taiwana and Cephalcia chui (both from Taiwan ; reference no. 3).