
Photo: Imgur
About 100 sightings of Pleń have been reported in Poland after the Second World War, the most recent of which have even been caught on camera. The phenomenon has been observed in the Carpathian Mountains, the Biebrza marshes, and the Białowieża Primeval Forest.
Although the first reports of the Pleń phenomenon can be traced back to Poland, it has since been observed in other parts of the world as well, including in the forests of Russia, Lithuania, Sweden, Norway, Bavaria, Hungary, Switzerland and North America.
Science has yet to offer a complete explanation for the phenomenon, but according to currently available information, the movement of thousands of tiny larvae as a giant unit simply ensures a greater speed. The larvae crawl over each other like a conveyor belt. The larvae on top of the pile crawl over their neighbors, who are also moving, meaning they move twice as fast, but then they also have to spend time at the bottom once they make their way to the top of the mass.
Overall, if the mass is made up of two layers, it moves about 1.5 times the speed of an individual, and if the number of layers is larger, the speed increases as well. It’s simply a more efficient way of getting around. As for the ultimate goal of this migration, lack of food or the drying effect of sunlight have been theorized by scientists.