A large number of mayflies swarmed streets, resembling drifts of moving snow in southern China.

Video filmed in the city of Yiyang in Hunan Province on September 4 shows a large number of mayflies flying in the sky and dropping onto the streets after dying.

The streets were covered by the dead mayflies, with footage showing a truck trapped on the road as it was slippery.

A man was heard saying: "You can see how thick (are the mayflies covering on the street). They are flying everywhere in the sky like snow."

According to the director of local agricultural and rural administration named Liu, the phenomenon happens every year. The mayflies live on water and only emerge as adults and fly out of the water when they mate.

The adult stage of mayflies is short, which can only last a few hours.

The mayflies are harmless to humans and crops as they do not eat as adults.

The video was provided by local media with permission.

9月4日晚，湖南益阳沅江市，大量蜉蝣漫天飞舞，铺天盖地如下雪一般，对出行造成很大不便。在黄茅洲大桥上因为满地蜉蝣，有车辆打滑发生事故。
9月5日，沅江市农业农村局植保植检站刘站长介绍，这种情况每年都会有，蜉蝣幼虫生活在水中，对水质要求较高，只有交配的时候才会羽化变为成虫飞出水面，因此这种情况在江河湖泊附近更明显。成虫期比较短，一般只能活几个小时，所以有“朝生暮死”的说法。又因为蜉蝣成虫期不进食，所以对人类和农作物都没有危害。（视频由湖南台提供）