The Reverdin's Blue is a species of butterfly, about 20mm in size and lives in some parts of Kanto and Chubu Regions of Japan. Unfortunately its habitat is shrinking year by year and there are many areas where the species is already believed to be extinct. To help save the butterfly from extinction, we first need to understand its habitat, activity range, and other aspects of its mode of life.
![[Image] Male (left) and female (right)](images/008.jpg)
Male (left) and female (right) examples of the Reverdin's Blue.
Male adults are characterized by the bright blue color of their wings while females have blackish brown wings. Larvae are less than 1 cm in length and only eat a shrub called Indigofera which grows after fields are burned off.
* Photographed by Michihito Watanabe
Nashigahara is a large area of grassland covering about 46km2. It is burned off every April. Mt. Fuji disappears from sight in a cloud of smoke as flames rapidly burn the land. The land then transforms itself as if rolling out a beautiful green carpet by early summer.
Nashigahara remains in this condition with human intervention that ensures the area is burnt off every year. It also has a special status as a training ground for the Japanese Self-Defense Forces, which sometimes prohibits the general public from accessing the area
As a result of these unique conditions, the Nashigahara grassland provides a precious habitat for the Reverdin's Blue. The Reverdin's Blue is currently is listed as a category II extinction risk ("vulnerable") in the Red Data Book*1
*1 Listing of Japan's endangered wildlife with information including habitat conditions.
![[Image] Mt. Fuji and grassland in June](images/010.jpg)
Nashigahara grasslands at the foot of Mt. Fuji
Certain grasslands located along the riverbanks have certain requirements, such as regular flooding, that keep them in their natural state. In Nashigahara's case, the requirements for maintaining the grassland include regular burning.
* Photographed by Michihito Watanabe
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