Now that oak processionary caterpillars had my consideration, I noticed that they weren’t a parochial German pest. Britain has had them since 2006, when London imported infested oaks from the Continent. Currently, the species has been spilling from Germany into Denmark for the primary time. The Netherlands, the place they’ve lengthy been current, recorded a doubling of infested oak bushes in contrast with final 12 months, and Switzerland’s forest-research institute known as 2026 “an exceptionally robust Eichenprozessionsspinner infestation 12 months.” France has been beset not solely with these caterpillars (processionnaire du chêne) but in addition with a intently associated species that has unfold northward from the Mediterranean: the processionnaire du pin, or pine processionary caterpillar. A good friend of mine, whose college campus in Nuremberg was infested with Eichenprozessionsspinner, informed me, “I feel nature is attempting to destroy us.”
Poisonous caterpillars, like lethal warmth waves, have gotten a daily a part of European summers. Eichenprozessionsspinner love heat, dry, and sunny springs, and the spring of 2026 was the sunniest in Berlin’s historical past. Warmth and photo voltaic radiation not solely assist oak processionary caterpillars survive after they hatch but in addition make them trigger-happy with their hairs in summer time. “The general pattern will probably lean towards an growing chance of mass outbreaks,” Thomas Sobczyk, a forest engineer who research the caterpillars and the moths they flip into, informed me in an e-mail. “From my perspective, there’s no different to coming to phrases with the oak processionary moth’s presence in residential areas.”
After I recovered, I visited Volkspark Jungfernheide, one in all Berlin’s largest parks and the positioning of one of many worst outbreaks within the space. It was practically empty of individuals. Staff had been vacuuming up caterpillars for weeks. They wore ventilated face masks and, on every hand, a number of gloves that have been duct-taped to their sleeves. I now not seen these women and men as caricatures of German overzealousness however as frontline heroes who ought to be applauded from balconies and open home windows. Their vacuum cleaners had initially been designed to suck asbestos out of outdated buildings; a vacuum bag may maintain forty kilos of caterpillars and their nests, and a employee may fill three luggage a day.
In June, the town’s twelve districts requested the Berlin Senate, which had been slashing metropolis companies for years, to declare the caterpillars a public-health menace, which might have unlocked further funding and made it simpler to make use of regulated pesticides. The request was denied. The state secretary for the atmosphere mentioned that nobody may have predicted the extent of this 12 months’s outbreak, although the numbers of Eichenprozessionsspinner had climbed yearly since 2023. In consequence, the districts may do little else however take away caterpillar nests—generally known as “tents”—from bushes. The district that encompasses the park, Charlottenburg-Wilmersdorf, had closed playgrounds and sports activities amenities, together with a swimming pool. Caterpillar hairs floated on the water’s floor, leaving swimmers with a necklace of purple stings.
At slightly biergarten that featured an outside theatre, I met an arborist named Gernot von Lyskowski. His agency, GvL, was one in all three corporations sucking up the caterpillar tents. “We haven’t had it this unhealthy earlier than,” he informed me. “We’ve been preventing right here in Jungfernheide for 4 or 5 years now.” Von Lyskowski initially turned an arborist as a result of he beloved climbing bushes when he was a child. “We weren’t even conscious of what was responsible for the itching again then,” he mentioned. The caterpillars aren’t unknown to Germans: within the fifties, for instance, lots of of individuals attending a competition broke out in rashes after they hid from a downpour underneath infested bushes. But the species was unusual sufficient that, in 1993, conservationists categorised the species as “threatened with extinction” in Berlin. Maybe at this time’s Eichenprozessionsspinner outbreak is much less like a overseas invasion than like a revolution, wherein a lowly factor rises as much as dominate ecosystems of which it has at all times been a component.
