北美的周期蝉有着奇特的生命周期。它们要经过一段漫长的时间——每13年或17年——才会成群地破土而出。自17世纪中叶起,科学家就对周期蝉的生命周期困惑不已。它们遵循着相同的生命周期:幼虫在地底生活13年或17年,然后在夏季大量出现。它们爬上树,蜕皮,成长 North American cycle cicadas have a peculiar life cycle. They will take a long time - every 13 or 17 years - to get out in small groups. Since the mid-17th century scientists have been perplexed by the life cycle of periodic cicadas. They follow the same life cycle: the larvae live in the ground for 13 or 17 years and then appear in abundance during the summer months. They climb the tree, molt, grow