Monarch butterflies(黑脉金斑蝶)are a common summer sight in the northern United States and Canada
These large orange and black insects(昆虫)brighten parks and gardens as they fly lightly among the flowers
What makes monarchs particularly interesting is that they migrate(迁飞)—all the way to California or Mexico and back
They are thought to be the only insect that does this
Every year in the late summer monarchs begin their journey to the south
Those heading for Mexico go first for the Louisiana-Mississippi area , then fly across the Gulf of Mexico into Texas
Once in Mexico , they settle themselves in one of about fifteen places in a mountain forest filled with fir trees
Each place provides a winter home for millions of monarchs
The butterflies are so many that they often cover entire