Anyone who roams through Berlin’s forests these days can make an unpleasant acquaintance: On Friday, the health administration issued a warning about the caterpillars of the oak processionary moth for the coming weeks. The hairs of the animals contain a poison that can trigger severe allergic reactions and inflammation.

According to the Senate Department, the typical symptoms range from itching to skin inflammation and irritation as well as inflammation of the eyes. When inhaled, the nose, throat and bronchi are irritated; People with previous exposure are at risk of shortness of breath. The symptoms could possibly only appear after 24 hours, especially since the allergenic hairs stick to clothing and shoes and can be dispersed by the wind.

According to Derk Ehlert, wildlife expert from the environmental administration, the burden of oak processionary moths in Berlin is roughly at the level of last year – i.e. “with a relatively small number of animals, but across the board”. Other federal states including Brandenburg are much more affected.

In Berlin, the plant protection office has registered relatively large populations in the Wuhlheide, the area around the airport lake in Reinickendorf and parts of the Grunewald; “wherever there are many oaks”.

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Oak processionary moths are moths that lay their eggs primarily in the crowns of pedunculate and sessile oaks. The caterpillars go through several larval stages until they pupate in July and the next butterfly generation hatches. According to Ehlert, the only moderately warm temperatures announced for the time after Pentecost are advantageous because the caterpillars then tend to stay in the treetops, which reduces the risk of contact for humans. On the other hand, when it is very hot, they would rather climb down in the morning and only stay in the treetops at night to eat.

The trees usually survive the infestation without permanent damage and regenerate themselves via the so-called St. John’s shoot at the end of June. This also applies to the bushes, which are attacked by the spider moth, which is currently conspicuous in some parks but harmless to humans. According to information, the oak processionary moths, which are often connected in long chains (“processions”), are an important source of food for birds, especially cuckoos.

The animals and their web-like nests, which can be as large as a soccer ball, do not have to be removed. However, it is recommended wherever contact with people is to be expected, for example in the vicinity of playgrounds and on forest and park paths. A strong jet of water or special suction devices can be used to remove it. According to Ehlert, household vacuum cleaners should never be used to tackle the spinners because the nettle hairs are only held back by special filters.