This study aimed to clarify the aquatic fauna in riffles and reveal adult records of aquatic insects in small moun-tain streams, Mizuya Stream and Noto Stream, flowing through Kasuga-yama Primeval Forest in Nara Prefecture. A large number of Gammarus nipponensis and Nemouridae (Nemoura and Amphinemura) nymphs were collected from two streams, nymphs of Baetis thermicus were predominated in both streams. However, the other fauna were fairly different between two streams. In Mizuya Stream, large numbers of Elmidae and Naididae were collected. In Noto stream, some Ephemeroptera species (e.g., Paraleptophlebia japonica, Ameletus montanus, Epeorus cumulus) and Simulidae larvae were predominant in numbers.
The larvae of Anisocentropus kawamurai and A. pallidus (Trichoptera: Calamoceratidae) were recorded from Gunma Prefecture, central Japan. The sizes of these larvae and cases and their habitats were also provided. Anisocentropus pallidus was found from Gunma Prefecture for the first time.
I counted the numbers of mature eggs in female abdomens of seven species of winter stoneflies, collected in Gunma Prefecture, central Japan. The females of Takagripopteryx nigra contained a large number of mature eggs (2000 - 4000), one of which had approximately 5500. The number of mature eggs of Eocapnia sp. Ec3 was the least, only up to 875. The females of other five species, Eocapnia nivalis, Apteroperla verdea, Apteroperla sp. A8, Eucapnopsis stigmatica and Eucapnopsis bulba, had approximately 2000 to 3000 mature eggs.
Larval and pupal microhabitats and physical environmental factors of Rhyacophila lezeyi were investigated in a highly acidic mountainous stream, Shibukuro Stream (pH3.0 in average) of Tamagawa River System, Akita Prefec-ture, northern Honshu from May 2017 to July 2019. Larvae were widely distributed both in the rapids and glides with extremely high abundance. Pupal cases were mostly found on downstream side of ventral surfaces of embedded boul-ders and more abundant in rapids than in glides with faster current speed. Pupal aggregations with 2-5 pupal cases were frequency observed and up to 29 pupal cases were aggregated.