Worries grow over monarch butterflies

Populations overwintering in Mexico may be on the decline

North America’s beloved monarch butterfly may be sliding into a long-term decline. While monarch numbers have fluttered up and down over recent decades, one research group now says that there’s enough data to spot a downward trend.

WINGS ON TREES Monarch butterflies overwintering in Mexico can cluster so densely that they hide the bark of a tree trunk.