Plague of secreting millipedes of Asian origin tormenting Swiss village

"I can't stand it anymore," Vreny Cencig, an Erstfeld resident, told local daily Luzerner Zeitung. "Every day since the beginning of summer, between 6am and 8am in the morning all I do is fight these insects," added Cencig. 

 

Cencig told Luzerner Zeitung that she sweeps hundreds off her balcony each morning and finds many more on sticky tape that she lays as defense traps around her home. Then she sprays them with gas or poison, only for hundreds, or even thousands, to take the place of the deceased the next day.

 

"The millipedes were already in the neighbourhoods of Aecherli and in Erstfeld for three to four years. But never was the plague as bad as this year, where thousands of these uninvited guests harass the life of residents," Paul Gwerder, a local freelance journalist and a member of the Erstfeld parish council, told The Local. 

 

Erstfeld resident Vreny Cencig lays tape on her doorstep to trap the invading creepy-crawlies. Photo: Paul Gwerder. 

 

Why exactly the Asian millipedes chose to settle in this quaint Swiss village remains a mystery, both to scientists and local residents. 

 

"They have been around in Central Europe for a longtime, but mainly in botanical gardens," Klaus Zimmermann, a researcher with Inatura, the Austrian-based natural history museum and research institute, told The Local. "They are inadvertently transported with plants from Asia to botanical gardens. But they are not usually found in the wild in Central Europe," added Zimmermann, who has conducted extensive research on the greenhouse millipede (Oxidus gracilis), also known as the hothouse millipede. 

 

Greenhouse millipedes have been found in compost in botanical gardens in Europe for centuries but originate from islands in the Eastern Indian Ocean, according to a research paper by Zimmermann published in Schaedlings.net in June 2017. The insects are rarely seen in the wild in Europe, although in Japan, where they are found in abundance, in the year 2000 a railway line had to be temporarily closed because of a mass swarming, according to Zimmermann's research. 

 

The millipedes pose no real danger to humans. On the contrary, they are generally found in compost – this is how they mainly arrived from Asia – and "fulfill an important function in our ecosystem," according to Zimmermann. 

 

Exasperated local residents in Erstfeld however aren't singing from the same hymn sheet. "We are repeatedly told these animals are useful, but for the residents they are just disgusting," local council spokesman Gwerder told The Local. 

 

Greenhouse millipedes in the wild, which are presumed to have usually fled from a nearby botanical garden or compost depot, generally arrive en masse, according to Zimmermann. 

 

"They will definitely spread fast too," the entomologist told The Local. "But such masses usually recline quickly. When they come to a place it is usually en masse, but after one or two years they usually disappear again. The adults only live for a year, unlike European millipedes that can live for eight." 

 

While the insects don't pose any health threat to humans, their sheer abundance in Erstfeld is driving local residents up the wall. Most of the town's 3,700 locals have to gas or poison the insects to rid themselves of them, but the insects nevertheless don't go quietly. They curl up and emit a nauseating liquid when threatened, adding to the distress of cleaning them up. 

 

Zimmermann says this isn't the first such manifestation of greenhouse millipedes outside of botanical gardens in Europe. The insects have been spotted from Zurich to Basel to Luzerne and last year a swarm invaded Vaduz, the capital of Lichtenstein. 

 

Two years ago, Zimmermann observed and studied a similar case in Feldkirch, a medieval city in the western Austrian state of Vorarlberg.

 

The good news for Erstfeld residents? "They are no longer there in Feldkirch," says Zimmermann, emphasizing that the species' one-year life span means they disappear as quickly as they appear. The unwanted arrivals in Feldkirch remained a few nights before disappearing back into the earth, according to Zimmermann's research. 

 

The animals mainly live in compost and are not generally known to reside in living plants, although they have taken a liking to salad plants – to which they are a threat – adds Zimmermann. But the greenhouse millipedes' recent behaviour in Erstfeld certainly seems unpredictable.

 

"Nobody knows why thousands are climbing houses," Zimmermann told The Local. "According to existing literature, they are blind and only leave the ground in exceptional circumstances." Zimmermann says he is investigating this development further in his research. 

 

"It's important to help people in such cases of mass invasions. When they are climbing houses like this they can cause extensive psychological distress to people," adds Zimmermann.

 

A spokesman for the canton of Uri told Luzerner Zeitung that because the animals don't pose a threat to agriculture or humans the authorities are unable to intervene, leaving local residents at the mercy of the plague. 

 

"Actual effective and lasting measures do not seem to exist. People have no choice but to hunt and eliminate the millipedes every day," Paul Gwerder told The Local.