9 The Kingly Monarch Butterfly

Monarch butterflies are a common summer sight in the northern United States and Canada. These large orange and black insects brighten gardens as they flit among the flowers. What makes monarchs particularly interesting is that 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 months, monarchs begin their trek to the south. Those heading for Mexico first go to the Louisiana-Mississippi region, then on to the Gulf of Mexico (some have been spotted on platforms there), before crossing into Mexico, where they establish themselves in one of about fifteen sites in the mountains, forests filled with fir trees. 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: does every butterfly make the round-trip journey? The answer is no. The average monarch lives only about nine months. So one generation may fly north and lay eggs in Kentucky, Louisiana, or Texas, and then die. The last generation of the season—about the fourth—will make the trek back to Mexico and restart the cycle.

Scientists learn about monarchs’ migration by capturing and placing identifying tags on the insects, then recapturing tagged monarchs and noting where they came from. By doing this, scientists can figure out things like the butterfly’s age and its route.

9 高贵的黑脉金斑蝶

黑脉金斑蝶是美国北部和加拿大夏季常见的景象。这些橙黑相间的大昆虫在花丛中飞舞，为花园增添了生机。黑脉金斑蝶特别有趣的一点是它们会迁徙——一路飞到加利福尼亚或墨西哥，然后再飞回来。它们被认为是唯一会这样做的昆虫。

每年夏末，黑脉金斑蝶开始向南迁徙。那些前往墨西哥的蝴蝶首先会飞到路易斯安那-密西西比地区，然后前往墨西哥湾（有人在那里的平台上发现过它们），之后进入墨西哥，在山区的约十五个地点之一定居，这些地点是布满冷杉的森林。每个地点都是数百万只黑脉金斑蝶的越冬家园，蝴蝶数量之多，常常会覆盖整棵树。

春天来临时，它们开始向北的长途迁徙。问题是：每只蝴蝶都会完成往返旅程吗？答案是否定的。黑脉金斑蝶的平均寿命只有约九个月。所以一代蝴蝶可能会向北飞，在肯塔基州、路易斯安那州或得克萨斯州产卵，然后死亡。这个季节的最后一代——大约是第四代——会跋涉回到墨西哥，重新开始这个周期。

科学家通过捕捉黑脉金斑蝶并给它们贴上识别标签，然后重新捕捉带标签的蝴蝶并记录它们的来源，来研究它们的迁徙。通过这种方式，科学家可以了解到蝴蝶的年龄和迁徙路线等信息。