Carolyn Kaster / AP

An adult cicada rests after shedding its nymphal skin, on the bark of an an oak tree early on May 5, 2021, on the University of Maryland campus in College Park, Maryland. Trillions of cicadas are about to emerge from 15 states in the U.S. East. Scientists say Brood X is one of the biggest for these bugs which come out only once every 17 years.

2021年5月5日清晨，马里兰州，在马里兰大学市分校校园里，一只脱落了若虫皮肤的成年蝉在一棵橡树上休息。美国东部15个州即将出现数以万亿计的蝉。科学家们说，孵卵X是这些虫子中最大的一种，它们每17年才出现。