Madrid authorities have concluded this year's campaign to combat the pine processionary moth, removing over 50,000 nests of these stinging caterpillars from trees. The operation, conducted since last November, covered parks and green areas across the city, aiming to reduce the public health risk, especially for children and pets. Municipal services used aerial lifts and telescopic saws to safely remove nests from heights of up to several meters. Residents are receiving guidance on how to avoid contact with the caterpillars' microscopic, stinging hairs.
Scale of this year's operation
According to various press sources, municipal services in Madrid removed between 50,000 and 53,500 pine processionary moth nests during the 2025/2026 season. The operation was conducted from November 2025 in the city's parks and other green areas.
Health hazard
The caterpillars of the pine processionary moth possess microscopic, stinging hairs that can cause severe allergic reactions of the skin, eyes, and respiratory tract in humans. For dogs, contact can be particularly dangerous, leading to serious inflammation and even tissue necrosis.
Methodology and prevention
Nests were removed by specialized teams equipped with aerial lifts and telescopic saws, allowing for work at significant heights. The action is preventive and cyclical, repeated every year during the autumn-winter period when the caterpillars build their silken structures.
Resident reaction and coordination
The campaign was met with a positive reception from residents, who have often reported concerns about the presence of caterpillars in recreational areas. The actions were coordinated by the Environment Department of the city hall in cooperation with Madrid's individual districts.
Madrid authorities conducted a large-scale campaign in the 2025/2026 season to combat the pine processionary moth (Thaumetopoea pityocampa), removing tens of thousands of this pest's nests from trees. According to media reports, the number of nests removed exceeded 50,000, with some sources citing over 53,500. The campaign, running since November 2025, covered city parks and other green spaces, constituting a key element of the annual fight against this insect. The primary motive for the action is protecting public health from the microscopic, stinging hairs of the caterpillars, which are easily released into the air. Contact with these hairs can cause severe allergic reactions in humans, including skin inflammation (dermatitis), eye irritation, and breathing problems. Small children and dogs are particularly at risk, as they can inhale the hairs into their nostrils or mouths during walks, which in extreme cases can lead to inflammation and tissue necrosis. To counter this threat, municipal services, equipped with aerial lifts and telescopic saws, systematically removed nests from heights of up to several meters. Each eliminated nest removes hundreds of potential caterpillars, which is crucial for population control. Madrid residents were informed about the progress of the work and received instructions on how to proceed if they encounter caterpillars or their nests. It is recommended to absolutely avoid contact, not touch the nests, and immediately report their presence in public areas to the appropriate services. The action is preventive and is repeated every year during the period when the caterpillars build their silken shelters. The scale of this year's operations indicates a significant and likely growing pest population in the capital region. Mass outbreaks of the pine processionary moth in Southern Europe have been a known phenomenon for decades, but in recent years, their intensification and expansion into new areas have been observed. Milder winters associated with climate change favor caterpillar survival and extend their feeding period. This problem affects not only forested areas but increasingly also urbanized areas where pines are popular ornamental trees. The operation was coordinated by the Environment Department of the Madrid City Hall in cooperation with the city's local districts. The initiative was met with approval from residents, who have long expressed concerns about the presence of stinging caterpillars in parks and gardens—places intensively used by families with children and people walking dogs. Authorities emphasize that removing the nests before the caterpillars hatch and spread in spring is the most effective method of reducing risk. The pine processionary moth problem in Spain poses not only an ecological challenge but also a social and health one, requiring constant, planned monitoring and intervention.