Thousands of earthworms crawl up the walls of houses in Vung Tau

On the morning of December 14, Mr. Nguyen Dang Khoa, in Ward 12, Vung Tau City, witnessed thousands of earthworms crawling on the wall in front of the gate and entering the yard of his house. The road in front of Mr. Khoa's house also recorded a large number of worms moving.

Mr. Khoa said he has lived in this area for many years, but this is the first time he has witnessed earthworms appearing in large numbers after the rains that have lasted for two days. "I used a hose to spray them out. As of noon today, there are still a few worms crawling on the ground," Mr. Khoa said.

Ms. Vo Thi Thu Hong, Vice Chairwoman of Ward 12 People's Committee, said that the locality recorded this phenomenon occurring in an empty land area with only three houses.

According to Ms. Hong, this place used to be a swamp, then it was filled in again. It has been raining a lot these past few days, causing flooding, causing "worms to have difficulty breathing or for some reason" to crawl up. Other places in the area have not recorded this situation.

Scientists around the world have several theories about why earthworms come out when it rains. According to Thea Whitman, a soil scientist at the University of Wisconsin-Madison, worms do not have lungs and absorb oxygen through their skin, and can absorb it from both water and air. However, Whitman notes that some species that require high levels of oxygen are more likely to come out of their burrows when it rains.

Another possibility is that rainwater in the soil is harming the worms in some way. For example, when the rain is acidic, or when harmful chemicals such as heavy metals are released.

Kevin Butt, an earthworm ecologist at the University of Central Lancashire in the UK, said that worms that emerge during rain can move more quickly on wet ground, instead of slowly burrowing through the soil as usual. They may make such trips to mate or migrate.