黑蝶

黑脉金斑蝶有一点特别有趣，那就是它们会迁徙，

What makes monarch butterflies particularly interesting is that they migrate ,

黑脉金斑蝶的数量降至历史最低点。

The population of Monarch butterflies is falling to record lows .

每一个地方都为数以百万计的黑脉金斑蝶提供了一个冬季的避难所。

Each side provides the winter home for millions of monarchs .

长途迁徙是黑脉金斑蝶的天性。

Migrating long distances is in a monarch 's blood .

每到秋天，在加州和墨西哥，数以千计的黑脉金斑蝶都会向西飞去。

Each fall , thousands of butterflies head west in California and Mexico .

黑脉金斑蝶——一种大型黑橙相间的昆虫

Monarch butterflies , the large orange-and-black insects ,

黑脉金斑蝶的平均寿命只有9个月。

The average monarch lives about nine months .

每年的夏季末，黑脉金斑蝶就开始向南迁徙，

Every year in the late summer , monarchs begin their migration to the south ,

科学家们通过捕捉昆虫并在它们身上贴上身份标签的方式研究黑脉金斑蝶的迁徙。

Scientists learn about monarch butterflies migration by capturing and placing identifying tags on the insects .

黑脉金斑蝶春季和夏季在美国的海湾沿岸和五大湖区繁殖。

Monarchs breed in the spring and summer on the gulf coast of the United States and in the Great Lakes region .

基因作物可以抵抗除草剂，这样农民就可以用除草剂除掉马利筋，而马利筋是黑脉金斑蝶最主要的食物来源。

The gene crops are designed to resist herbicides and that 's allowed farmers to wipe out milkweed , which is the main food source for Monarches .

每年春夏，在美国的许多地方都可以看到黑脉金斑蝶，它们在墨西哥中部度过冬季时遍布大片森林。

The butterflies seen each spring and summer in many parts of the U.S. , spend their winters in central Mexico , where they cover vast stretches of forest .

每年迁徙时，过冬的黑脉金斑蝶会占据50平方英亩的森林，可是现在它们只占了不到3英亩。科学家认为这与墨西哥自然环境的砍伐现象有关。

The wintering butterflies that used to cover up to 50 square acres on their annual migration , now occupy fewer than 3 acres of forest . Scientists think logging in the Monarch , Mexican habitat , has something to do it .