Fewest Monarch butterflies migrating
Jan 29, 2014, 5:15 PM EST
MARTY MELVILLE/AFP/Getty Images
The migration of Monarch butterflies to mountains in Mexico has been tracked every year since 1993, and this year has shown the fewest number of colonies. The migratory phenomenon is in danger of disappearing. Herbicides are partially to blame.
Background:
Migrating Monarch Butterflies in "Grave Danger," Hit New Low [National Geographic]
Monarch Butterflies Falter Under Extreme Weather [New York Times]
