Massive mayfly swarm captured in C China's Hunan

Footage has captured the moment massive mayfly swarm swept the streets in the city of Yuanjiang, central China's Hunan Province. 　

In the footage, the insects can be seen covering the ground and sky. It appears as though snowflakes are falling down. 　

According to the Yiyang Ecology and Environment Bureau, the occurrence is a natural phenomenon that happens in the autumn and spring, and the particular bug is called a mayfly (Ephemeroptera), local media relayed. 　

The spectacle was spotted in Yuanjiang around September every year.