Butterflies have evolved in remarkable[1] ways that help them avoid being eaten by birds, lizards, and other predators.
　　We think of butterfly wings as being colorful, but many are relatively drab on the underside. Some butterflies protect themselves through camouflage -- by folding up their wings, they reveal the undersides and blend in with[2] their surroundings. Through this strategy, they become nearly invisible to predators.
　　Bright colors and distinctive wing patterns can, however, be advantageous. The caterpillars of many species feed on toxic plants, and throughout their lives, their tissues are poisonous to predators. The adult butterflies make no attempt to hide themselves; instead, their bright, warning coloration is like a neon sign[3]. A bird that eats one of these toxic butterflies remembers the experience -- and avoids repeating it.
　　Some butterflies simply fool their predators. As caterpillars, they feed on nontoxic plants, and when they become adult butterflies, they are perfectly good food. However, they have evolved wing colors and patterns that look almost exactly like those of the toxic species -- a phenomenon called mimicry. Birds and lizards, who have learned to avoid bold warning coloration, leave[4]these imitators alone.

自我保护

　　蝴蝶进化后的非凡成果是，它们能使自己避免遭到鸟类、蜥蜴和其它天敌的吞食。

　　在我们眼里，蝴蝶的翅膀绚丽多姿，而它们的下腹却呈土褐色，十分单调。一些蝴蝶通过伪装来达到保护自己的目的——把漂亮的翅膀收折起来，露出土褐色下腹，与周围环境融为一色。在这种保护措施的作用下，天敌几乎无法察觉它们的存在。

　　绚丽的色彩和与众不同的翅膀形状却也益处颇多。许多蝴蝶的幼虫以有毒植物为食，因而终其一生，它们的身体中都含有让天敌发悚的毒素。因而成年蝴蝶无须隐藏自己，相反，它们以那霓虹灯般夺目的色彩来警告来犯者。吃过毒蝴蝶的鸟类一定不会忘记这个教训——千万不要重蹈覆辙。

　　而有一些蝴蝶完全把它们的天敌愚弄了。当它们还是幼虫的时候，吃的是无毒植物，成为蝴蝶后自然是天敌们不错的美食。然而经过进化后它们的翅膀和形状完全酷似毒植物——这种现象在生物学上被称为拟态。那些学会了要远离醒目色彩的鸟类和蜥蜴则唯恐对模仿者避之不及。