Germany battles aggressive outbreak of poisonous caterpillars

By Sebastian Shukla, Sophie Tanno, CNN

Berlin (CNN) — Authorities across Germany have been battling an aggressive outbreak of poisonous caterpillars, which can cause severe health issues and have led to the closure of parks and other outdoor spaces, including in Berlin.

The oak processionary moth caterpillars are covered by microscopic, barbed hairs containing a toxin that can cause rashes, conjunctivitis and breathing difficulties if they come into contact with humans. The toxic hairs break easily and can be spread over long distances by the wind.

The creatures also form white, silky nests on the infested oak trees, which contain more of the toxic hairs.

The caterpillar outbreak is particularly severe in Berlin with the districts of Charlottenburg-Wilmersdorf, Spandau and Friedrichshain-Kreuzberg considered hotspots.

The result is that many of the city’s most popular green spaces are now look reminiscent of crime scenes, with red and white tape warning people not to get too close.

In the western district of Spandau, authorities are urging people to avoid a 39-acre local park known as the Wilhelm-von-Siemens-Park, as well as adjacent schools, daycare centers and streets, according to the official portal for the state and city government of Berlin.

CNN visited Berlin’s second-largest park, Jungfernheide, one of the worst affected in the city’s Charlottenburg-Wilmersdorf district.

Two cherry pickers, with seven workers dressed in full blue protective gear, including ventilation masks, were wielding the kind of vacuum machines designed for asbestos management, sucking the nests from branches roughly 20 meters (65 feet) off the ground.

The use of these suction cleaners ensures that none of the 700,000 or so toxic micro-hairs found on each caterpillar escape.

A city official overseeing the work told CNN that 2,000 trees in the park were suffering from infestation and are cordoned off. He acknowledged that there was no way to eradicate the problem. Instead, the aim is damage limitation, he said, with workers tackling the trees closest to the paths used by visitors.

The official added that the team wanted to be able to clear around 20 trees a day, but the level of infestation varied widely. He said over the weekend one crew had spent a whole day clearing one tree with 800 nests in.

Berlin’s authorities are currently advising people to ensure clothes are thoroughly cleaned after every park visit and to keep windows and doors closed when possible.

Other prominent infestations have been reported in Hamburg and the western German state of North Rhine-Westphalia, according to EPS-Radar, a website and digital map which has been tracking the outbreaks.

The website’s designer, Britta Wunderwald, told CNN she usually works in marketing but decided to set up the map, with the help of an AI tool, following a visit by a friend’s son who experienced symptoms typical of exposure to the caterpillars.

“I was wondering if I can go outside, and where a safe area to have a picnic was, and then I saw there is no actual map for this year,” she said in a phone interview.

“I hope that next year it’s getting taken more seriously (by the council), that they act in advance,” she added.

Urban nature expert Derk Ehlert warned in a post on the city of Berlin website against approaching and touching the caterpillars or their nests. According to Ehlert, more caterpillars have been sighted in Berlin this year than in previous years.

In a post last year on the Nature Conservation Foundation of Berlin website, he said that the caterpillars originated in southern Europe but have gradually been spreading northward.

The oak processionary moth is particularly prominent in hot and dry weather. While the insect has long been present in Germany, its increasing prevalence is due to climate change and is linked to biodiversity loss, according to the EPS-Radar website.

As well as itching and breathing difficulties, contact with the caterpillars’ hairs can also cause hives or a rash, and, in severe cases, an allergic reaction including anaphylactic shock.

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