European authorities are coordinating responses to an aggressive outbreak of invasive oak processionary moth caterpillars causing severe health hazards [1].
The spread of this species represents a significant public health risk because the caterpillars possess toxic hairs that trigger respiratory problems and skin rashes. Because the species is invasive and expanding, it threatens both urban public spaces and natural forest ecosystems across the continent [2, 3].
The outbreak was reported June 23, 2026 [1]. While the infestation is widespread, the western Ruhr region of Germany has emerged as a primary hotspot [4]. In Berlin, the situation has escalated to the point that authorities have closed parks and other outdoor spaces to protect the public [1].
Each individual caterpillar carries hundreds of thousands of microscopic hairs [5]. These hairs are not only dangerous upon direct contact but can be projected through the air for several hundred meters [5]. This airborne capability increases the risk of exposure for people who are not in immediate contact with the insects.
The infestation extends beyond Germany. Cases have been reported in Belgium and the Netherlands, with isolated sightings appearing in Portugal [2, 4]. In the U.S. and the United Kingdom, the Department for Environment, Food & Rural Affairs (Defra) is currently monitoring a specific site in Derbyshire where the caterpillars were spotted [6].
Experts said the population is expanding due to favorable climate conditions and the accidental transport of nests [2, 1]. The coordination between German authorities and Defra aims to contain the spread and provide public warnings to prevent further injuries.
“The hairs can be projected up to several hundred metres through the air.”
The rapid expansion of the oak processionary moth highlights the intersection of climate change and biosecurity. As favorable temperatures allow invasive species to migrate further north and west, urban centers face new public health challenges that require the closure of green spaces and increased government surveillance of biodiversity.
