The Secret Agent Worms are equipped with scuba gear, but most worms are not. Therefore, your average worm runs the risk of drowning when it rains.
During a heavy rain, wormholes flood and the soil becomes filled with water. To keep from drowning, many worms come out of hiding. Unfortunately, some of them wind up on the sidewalk, where their chances for survival aren’t much better.
Worms lie on the sidewalk after a rain because their wormholes are flooded with water.
Photo: U of I College of ACES-ITCS