Mt. Takao is considered one of the three major habitat of insects along with Minoo (Osaka prefecture) and Kibune (Kyoto prefecture) and it has long been loved by researchers of insects because of number of species and the easy access from the Metropolitan area. There are many insects first found in Mt. Takao and named after "Takao" such as Takao Shachihoko （Hiradonta takaonis Matsumura） and Takao medaka kamikiri (Stenhomalus takaosanus).
Main region: Honshu, Shikoku, Kyushu and Tsushima.
Found at streams from midstream to upstream on hills and mountains.
It was named after French zoologist Dr. Davidius Nanus in 19th century.
Body is black with yellow stripes from thorax to abdomen.
Three yellow spots are large on sides of thorax and the base of front legs of both female and male are yellow.
Seen at streams around Mt. Takao area from April to May.
Male hold territory and rest on stones and stay alert while waiting for a female to mate.
Female hovers in air alone and lay on water surface.
●Length about 40 to 50 mm
●Adult Flight Season April to about July
Found at streams from midstream to upstream on hills and mountains.
It was named after French zoologist Dr. Davidius Nanus in 19th century.
Body is black with yellow stripes from thorax to abdomen.
Three yellow spots are large on sides of thorax and the base of front legs of both female and male are yellow.
Seen at streams around Mt. Takao area from April to May.
Male hold territory and rest on stones and stay alert while waiting for a female to mate.
Female hovers in air alone and lay on water surface.
●Length about 40 to 50 mm
●Adult Flight Season April to about July