它们又回来了:预计今年会出现数百万只蝉

In parts of southwestern Virginia, North Carolina and West Virginia, it's nearly time for a brood of the insects to emerge for their once-in-17-year mating season. As many as 1.5 million cicadas could emerge per acre. And did we mention the bugs are known for their distinct — and overwhelming — chirping?

在维吉尼亚州西南部、北卡罗来纳州和西弗吉尼亚州的部分地区，几乎到了17年一次的交配季节，一窝昆虫出现的时候了。每亩地可能出现多达150万只蝉。我们有没有提到过这些昆虫以其独特的、压倒性的鸣叫而闻名?

"Communities and farms with large numbers of cicadas emerging at once may have a substantial noise issue," predicts Eric Day of Virginia Tech's department of entomology. He tells Virginia Tech Daily, "Hopefully, any annoyance at the disturbance is tempered by just how infrequent — and amazing — this event is."

“同时出现大量蝉的社区和农场可能存在严重的噪音问题，”弗吉尼亚理工大学昆虫学系的埃瑞克·戴预测说。他在接受《弗吉尼亚理工日报》采访时表示:“希望这一事件的罕见性和惊人性能够缓和人们对这一事件的不满。”

Periodical cicadas — unlike annual cicadas — emerge every 13 or 17 years, depending on the species. Brood IX, as this grouping is dubbed, last emerged in 2003.

周期性蝉与一年生蝉不同，它们每13年或17年出现一次，具体时间取决于物种。这一群体被称为第9窝，最后一次出现是在2003年。

Virginia Tech Daily notes that the 13-year or 17-year timing of cicada breeding cycles is still something of a mystery.

《弗吉尼亚理工大学日报》指出，蝉的繁殖周期是13年还是17年仍然是个谜。

The insects spend a majority of their lives underground, in an immature "nymph" state.

这些昆虫大部分时间生活在地下，处于不成熟的“蛹”状态。

Their timing isn't always exact. Some periodical cicadas have been seen years early; climate change may be a cause. Once they're done, they die within a few weeks.

他们的时机并不总是准确的。一些蝉在几年前就出现了;气候变化可能是一个原因。一旦完成，几周内就会死亡。