The yellow-legged hornet Vespa velutina was accidentally introduced into near Oita port in Japan, and firstly founded the colony in 2018. We estimated its origin by the morphological comparison among the subspecies of V. velutina, and also by the mitochondrial DNA sequence analysis. Our results revealed that the hornet which was collected in Oita was V. v. nigrithorax, and its mitochondrial DNA haplotypes unmatched the unique haplotype which present in Taiwan, China (Jiangsu), South Korea, and Japan (Tsushima, Iki, and Kitakyushu). These findings suggest that the origin of V. velutina in Oita is other regions, and seems to be introduced via the regular routes of cargo ships.

The zig-zag leafhopper, Maiestas dorsalis (Motschulsky, 1859) (Hemiptera: Cicadellidae), is a minor pest of rice in Asia. To investigate the fauna of egg parasitoids associated with leafhoppers in rice field, we deployed sentinel egg traps of M. dorsalis on rice seedlings in Fukuoka Prefecture, Kyushu Island, Japan. Females of two fairyflies, Lymaenon aureus (Girault, 1911) and L. litoralis (Haliday, 1833) (Hymenoptera: Mymaridae) were reared from the deployed sentinel eggs. This is a new host record for L. aureus. Additionally, new distributional records of both species from Honshu Island are presented.

Hydaticus grammicus (Germer, 1827) (Coleoptera: Dytiscidae) is a common diving beetle with a body length of 9.0–11.0 mm and yellowish brown with vertical stripes on their elytra. We found an unidentified beetle resembling H. rhantoides Sharp, 1882 because of dark brown on its body color in Hyogo Prefecture, Japan. Based on the phylogenetic analysis using mitochondrial COI gene sequences (646 bp), we concluded that the unidentified beetle is a color variation of H. grammicus (no stripe type). This color variation with no stripe is the first report of this species.