The caterpillar crawls away from the milkweed plant in search of a safe spot to begin the pupa stage of the monarch butterfly ...

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.

but rather a plant that is vital to its life cycle, yet a damaging weed to crops. According to the proposal by the U.S. Fish and Wildlife Service to list the monarch butterfly as threatened ...

The monarch butterfly population has declined in recent ... generation of the year (meaning butterflies that complete the life cycle and survive to see winter) that migrate. The migrating insects ...