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Cordulegastridae consists of six genera, about 60 species in the world and in Japan two genera with four species occur. In Southeast Asia and the Far East seven species of the genus Anotogaster occur. Among them, Anotogaster sieboldii is the largest species in Japan, with a wingspan of 12-14 cm, and is familiarly called “oniyanma”. It is distributed widely from Hokkaido, Honshu of the Mainland, Shikoku, Kyushu to the Southwestern Islands. Females oviposit dynamically into the mud of streams. Larvae inhabit small streams at lowland hills and bogs. Adult flying season is from mid-June to October.