Insects in Kikuchi Gorge
Diverse plant life and an abundance of fresh water sources make Kikuchi Gorge a favorable environment for a wide variety of insects. Among the more than 1,000 local species, the following are relatively easy to spot.
The small Celastrina sugitanii butterfly (Sugitani rurishijimi) emerges from its chrysalis in mid-spring, around the time when the cherry trees in the gorge burst into bloom. Its wings are dark blue on the top side and whitish-gray with small black dots on the underside. Living only for two months at most, the species is often seen around puddles near the river between March and May.
Soon after the Celastrina sugitanii’s time is over, the appearance of the white flowers of the utsugi (Deutzia crenata) shrub attracts butterflies such as the Japanese flash (torafu shijimi; Rapala arata), whose wings are deep blue on the top side while the underside is adorned by a tiger-like spot of orange and black alongside a white and brown stripe pattern; the white admiral (ichimonjicho; Limenitis camilla), distinguished by the stark white bands on its dark-brown wings; and the orange and black large map (sakahachicho; Araschnia burejana).
From April to around July, several kinds of broad-winged damselflies can be spotted flying over the rapids of the Kikuchi River, preying on tiny aquatic insects. Mnais pruinosa (asahina kawatonbo) is about 5 centimeters long with an emerald-green body and wings that vary in color from a bright orange to a barely visible gray, whereas Mnais costalis (nihon kawatonbo) has slightly darker, orange-brown wings on a metallic-blue body.
June is the season for the Luciola parvula firefly (himebotaru), a tiny beetle that is almost impossible to spot during the day but emits bursts of bright-yellow light from just after sunset to close to midnight.
Later in summer, the alpine black swallowtail (miyama karasuageha; Papilio maackii), a large butterfly with a wingspan of around 12 centimeters, can often be found around puddles and small riverside pools. Its wings are black on the top side and covered with iridescent blue or green scales. The Japanese peacock swallowtail (karasuageha; Papilio dehaanii) is similar in color but somewhat smaller, and the gap between its fore- and hindwings is less pronounced than that of the alpine black swallowtail.