Hundreds of black caterpillars make strange writhing circle formation

Hundreds of caterpillars were seen moving strangely in a writhing ring formation in a woman's yard in Lai Chau Province, northern Vietnam.

According to the filmer, she saw a strange black circle in front of her yard on December 7, 2018. As she approached she saw the caterpillars were not moving in a straight line but are moving in a circular pattern.

The insects were moving and narrowing the circle. This reportedly was the first time she saw the caterpillars moving in this way.