A、Evolution of monarch butterflies. B、Living habits of monarch butterflies. C、Migration patterns of monarch butterflies. D、Envir

Monarch butterflies, the large orange and black insects, are a common summer sight in the northern United States and Canada. They brighten parks and gardens as they fly among the flowers. What makes monarch butterflies particularly interesting is they migrate—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 migration to the south. Those heading for Mexico go first for the Louisiana Mississippi region. Then they fly across the Gulf of Mexico into Texas. Once in Mexico, they establish themselves in one of about 15 sites in a mountain forest. Each site provides a winter home for millions of monarchs. The butterflies are so numerous that they often cover entire trees. When spring comes, they begin their long journey north. The question is often asked whether every butterfly makes the round trip journey every year. And the answer is no. The average monarch lives about nine months. So one flying north might lay eggs in Louisiana and then die. The eggs of that generation may be found in Kentucky; the eggs of the next generation may end up in Wisconsin or Michigan. The last generation of the season about the forth will make the journey back to Mexico and restart the cycle. Scientists learn about monarch butterflies’ migration by capturing and placing identifying tags on the insects. By recapturing a tagged monarch and noting where it came from, the next scientist can figure out things like the butterfly’s age and its routing.
    Question 12. What is unique about monarch butterflies according to the speaker?
    Question 13. Where do monarch butterflies settle at the end of their migration?
    Question 14. What does the speaker say about monarch butterflies’ reproduction?
    Question 15. What is the talk mainly about?