They registered an unprecedented formation. The forest phenomenon amazes

The film quickly spread on the network, and in the comments it swarmed with speculation – from the guesses of an unknown animal species to suggestions that it is a sign of the upcoming disaster.

What is pleń?

Although it looks disturbing and almost foreign, pleń is a natural phenomenon. It consists of thousands of larvae of flies, most often plenary earth. These small insects, reminiscent of the appearance of fruit flies, in the larval stage can create compact, synchronized groups moving in a way reminiscent of the journey of one organism.

Why are they doing this? This is not fully known, as the foresters from Świerklaniec emphasized: “It is not entirely known why the larvae of the earthly species of the plearseer create such crawling structures and what is aimed at their journey.”

Such clusters can reach a length of up to several meters, and creeping larvae release mucus, which makes it easier to move around uneven terrain and probably allows you to maintain a compact structure. Scientists suppose that the journey of larvae may be related to the search for more favorable conditions for further development or protection against predators – the creeping mass in the group looks like a much larger body, which can deter the threat.

Rare and difficult to observe a phenomenon

The pleń is rare and is very difficult to observe. He is known primarily for mountain areas – the Tatra Mountains, the Bieszczady Mountains, as well as from some regions of the Żywiec Beskids and the Białowieża Forest. It usually appears in moist, shady forests, usually in the summer, when the conditions are optimal for larvae activity.

Although the first mention of such a phenomenon appeared already in the 17th century – then in Silesia Zoologist Caspar Schwenckfeld described them as “Ascarides Militares” – to this day scientists are not able to clearly determine what directs larvae to this collective march. So far, only several dozen cases of Pleni observation have been reported in Poland.

Folk beliefs and symbolic meaning

The pleń has aroused emotions for centuries and was the subject of numerous legends. In the folk tradition, his appearance was of particular importance. Depending on the region and beliefs, he was treated as an omen – good or bad. As the Świerklaniec Forest District noted: “According to folk beliefs, the appearance of Pleń was treated in two ways: some considered a prophecy of upcoming misfortunes, others thought that it was a trailer for happiness, success and good crops.”

In some regions of Poland, e.g. in Podhale, the pleń was considered a sign of harvest – it was collected, dried and stored in barn as an amulet for prosperity. It was believed that if the larvae crawls in a certain direction – for example, north – this means the coming good times.

Fascination and disgust – people’s reactions

The film published by the Świerklaniec Forest District aroused mixed emotions. Some were fascinated by the extraordinary movement and behavior of the larvae, others wrote that the recording caused a gag reflex. This is a typical reaction to contact with something that looks unnatural, although it is completely in line with biology.

Tourists and Internet users reacted in a similar way in the past – e.g. during the recording of Plecans in the Bieszczady Mountains a few years ago, where many witnesses thought initially that they were dealing with a snake or a mysterious creation from legends. Even specialists admit that the sight of such a large number of larvae moving as one body can arouse consternation and sometimes even fear.