蛹

蛹巴西͞o´pə[关键］人生的第三个阶段昆虫它经历了完全的蜕变，即从卵经过幼虫和蛹阶段发展到成虫阶段。鞘翅目(甲虫)、双翅目(苍蝇、蚊子和蚊蚋)和鳞翅目(飞蛾和蝴蝶)成员的完全变态是其特征。在进入蛹期之前，昆虫是一个活跃的幼虫，通常形状像蠕虫。蛹是昆虫转变为成虫的休息阶段。它不进食，也不增大大小，通常它在外面是不活跃的，被坚硬的被膜覆盖。然而，体内发生了大量的代谢活动。在这个阶段，一些幼虫的器官被破坏，一些成虫的器官被启动。其他成虫器官是由幼虫体内已有的结构发展而来的。在蛹期结束时，被皮脱落，成虫或成虫出现。飞蛾的蛹通常有一个额外的外层，称为茧，是由幼虫(称为毛虫)在进入蛹阶段之前建造的。 Cocoons may be made of bits of woody material held together by silk strands, or woven entirely of silk. Some cocoons are formed on or under the ground, some under tree bark; others are suspended from branches or twigs. Some moths form cocoons by wrapping leaves around themselves and gluing them together with silk. Cocoon building occurs in other insects, e.g., wasps; the material and design of the cocoon vary greatly from one group to another. Very few butterflies make cocoons, but the butterfly pupa, called a chrysalis, is usually suspended by a silk thread, and its integument is often sculptured and brightly colored. The chrysalis of the monarch butterfly is soft green with gold spots. A few insects, e.g., the蚊子，有活跃的蛹。不同昆虫的蛹期不同，从几天到几个月不等。许多昆虫在蛹期过冬，而成虫则在春天出现。

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