The annual migration of monarch butterflies is one of science's great mysteries: millions of monarchs know the correct path ...

Monarch butterflies are important culturally and ecologically across North America. Generations have watched in wonder as yellow-and-black striped caterpillars fold into green-and-gold chrysalises and ...

For thousands of years, millions of monarch butterflies have migrated from the northern U.S. and Canada to Mexico for the winter. But exactly how they know where to go is still a mystery.

The plight of the monarch butterfly could cost farmers a valuable tool in the fight to protect crops from weeds and pests. An effort is underway to list the monarch butterfly as threatened under ...