(Joel Sartore/Nat Geo Stock/Caters ) Big numbers: The reserve hosts up to a billion butterflies each year, after they have made their migration from North America in a 2,500 mile journey to the warmer climes of Mexico between October and March.
Beautiful Orange Glow of Millions of Butterflies Flying Around a Reserve
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OCTOBER 22, 2012
Mark Duell, Daily Mail

Congregating on trees in their millions and creating a wonderful orange glow as they fly around, the beautiful monarch butterflies at the Sierra Chincua reserve in Mexico are a spectacular sight. The reserve hosts up to one billion butterflies each year, after they have made their migration from North America in a 2,500-mile journey to the warmer climes of Mexico.
Read more: Daily Mail