FILE - In this Dec. 9, 2011 file photo, a Monarch butterfly perches on a branch in the Sierra Chincua Sanctuary in the mountains of Mexico's Michoacan state. The Monarch butterflies arrive in central ... more 
FILE - In this Dec. 9, 2011 file photo, a Monarch butterfly perches on a branch in the Sierra Chincua Sanctuary in the mountains of Mexico's Michoacan state. The Monarch butterflies arrive in central Mexico usually around the first week of November, after their yearly migration from Canada and begin their return around March. (AP Photo/ Marco Ugarte, File) less 
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Associated Press | Photo By Marco Ugarte, File
Thu, Aug 16, 2012 1:02 AM EDT