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(单词翻译:双击或拖选)
Silkworms have been bred over thousands of years to behave quite unlike their caterpillar2 cousins in the wild. That’s because people purposely breed silkworms to fit this job description:
WANTED–Superlative silk producers. Benefits include housing, unlimited3 food and protection from all predators4. Wanderlust greatly discouraged. No opportunity for travel.
Obviously, what makes a good silk producer in captivity5 is very different from what helps a caterpillar survive in the wild. Commercial silkworms are dynamos at silk production, and compared to their wild relatives, rather sluggish about everything else.
Outdoors, you’ve probably seen caterpillars6 crawling to find food or hide from birds, but commercial silkworm caterpillars hardly move. For silk production, they’re kept on open trays because they’re content to stay put, as long as they have a steady supply of mulberry leaves. Even when they reach the moth7 stage, commercial silkworms are surprisingly immobile. Wild moths8 fly to evade9 predators and to lay their eggs in different areas. However, commercial silkworm moths haven’t needed to do these things for thousands of years. They’ve completely lost the ability to fly, even though they still have wings!
Here’s another difference. In the wild, moths are often very particular about where they’ll lay eggs. This ensures that baby caterpillars can chomp10 their favorite leaves as soon as they hatch. Commercial silkworm moths have lost that instinct too. They’ll even lay eggs on a sheet of paper, where it’s easy for humans to keep track of them.
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1 sluggish | |
adj.懒惰的,迟钝的,无精打采的 | |
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2 caterpillar | |
n.毛虫,蝴蝶的幼虫 | |
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3 unlimited | |
adj.无限的,不受控制的,无条件的 | |
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4 predators | |
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面) | |
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5 captivity | |
n.囚禁;被俘;束缚 | |
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6 caterpillars | |
n.毛虫( caterpillar的名词复数 );履带 | |
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7 moth | |
n.蛾,蛀虫 | |
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8 moths | |
n.蛾( moth的名词复数 ) | |
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9 evade | |
vt.逃避,回避;避开,躲避 | |
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10 chomp | |
v. (人、动物进食时)大声地咬,嚼得很响 | |
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