Field studies of the winter stoneflies (Plecoptera) in the upper part of the Asagaigawa River, in Niigata Prefec-ture, Japan, from December 2020 to March 2021, resulted in only two species, i.e. Apteroperla tikumana (Uéno, 1938) and Eocapnia nivalis (Uéno, 1929). The numbers of individuals of small sized species, i.e. A. tikumana accounted for 97.4 per cent of all, and the period of the emergence was January to March. Like E. nivalis in Asagaigawa River, if only one large sized species inhabit in the river, the number of individuals of that species was extremely smaller than the small sized species. Large sized species appeared about a month earlier than small sized species.
Adults of Helicopsyche yamadai Iwata, 1927 (Trichoptera: Helicopsychidae) were collected from Karatsu City, Saga Prefecture, northern Kyushu, Japan. The morphological characteristics of male and female of this species are described and illustrated.
The following is an introduction to the species of stoneflies collected during the survey in the Satsunai River and the Tottabetsu River, Hokkaido, Japan. Sixteen stonefly species were collected during the survey, with at least half of the species inhabiting the hyporheic zone. Furthermore, we found the genus Utaperla Ricker, 1952 of the family Chloroperlidae. This is the first record of this genus from Japan.