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Hidden Wonders

[Hidden Wonders of Japan] Butterflies Huddle Up to Get Through the Winter

On Amami Oshima island, Ceylon blue glassy tiger butterflies hibernate together on branches, typically until early March, waiting for warmer temperatures.



Ceylon blue glassy tigers hibernate together on January 11 in Amami City, Kagoshima Prefecture. (©Kyodo)

In a forest along the coast of Amami Oshima Island in Kagoshima Prefecture, a group of Ceylon blue glassy tigers was spotted hibernating together. The butterflies, called Ryukyu Asagi Madara in Japanese, have a distinctive blue pattern on their wings. 

When the temperature drops below 15 degrees Celsius (59 degrees Fahrenheit), these migratory butterflies tend to cluster together on tree branches.

The brown wings of the Ceylon blue glassy tiger have a light blue pattern. (©Kyodo)

This natural phenomenon usually continues until early March, and observing the butterflies is a popular seasonal tradition among nature enthusiasts and tourists.

"We used to be able to see several thousands of these butterflies in the past," says Kenichiro Tomikawa, an expert on insect ecology from Amami City in Kagoshima Prefecture. "But in recent years, their numbers have been declining."


(Read the article in Japanese.)

Author: The Sankei Shimbun

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