An invasive and dangerous caterpillar species known for causing severe skin and respiratory reactions has been discovered at a daycare in Horsens, Denmark, prompting swift action by city authorities.
Toxic Caterpillar Found at Daycare in Horsens
Denmark is facing an emerging public health concern as the oak processionary moth (Thaumetopoea processionea), a hazardous insect nicknamed the “caterpillar from hell,” has now appeared in the Jutland region. For the first time in the area, the larva was recently discovered in a tree located at a daycare center in the city of Horsens. Local authorities have since taken steps to remove the caterpillar from the area.
The caterpillar’s tiny hairs — which easily become airborne — contain a toxin that can lead to severe itching, rashes, and, in some cases, breathing difficulties. This toxic caterpillar in Denmark poses risks to skin and respiratory health. The larvae, typically found on oak trees, have progressively been spreading across southern Denmark, with the city of Odense on the island of Fyn currently being the most severely impacted hotspot.
Swift Action in Horsens
Upon finding the nest earlier this week, Horsens Municipality acted quickly. Professional pest control teams were dispatched to remove the invasive insect colony. According to municipal representatives, there have been no reports of children or staff experiencing symptoms as a result of exposure at the daycare.
Officials in Horsens are remaining vigilant. The local government announced that the area around the infected tree will be monitored closely moving forward, especially during the summer months when the caterpillars are most active. Additional inspections are now planned for playground trees and other nearby green areas to reduce the potential for further spread.
Odense Struggles to Contain Larger Outbreak
While the threat in Horsens was contained swiftly, other areas in Denmark are facing bigger challenges. In Odense, the oak processionary caterpillar has spread extensively throughout city parks and residential areas. Efforts to remove the pest have already cost the city over 300,000 Danish kroner (approximately $43,000 USD), and officials warn that resources are being stretched thin. As a result, the city has had to prioritize high-risk locations such as schools, playgrounds, and senior homes for treatment.
High Public Health Risk
The threat posed by the oak processionary caterpillar, a toxic caterpillar in Denmark, stems from the thousands of microscopic hairs that cover the larva’s body. These hairs contain a protein called thaumetopoein, which triggers severe allergic reactions. Health authorities warn that even indirect contact — for example, being near a tree where the caterpillars are nesting — can be harmful. The hairs can be carried by the wind, and under the right conditions, can drift as far as 10 to 15 meters (33 to 49 feet) from the nest.
Exposure can result in painful skin rashes, eye inflammation, and respiratory issues. In particularly sensitive individuals, the result can be serious asthma-like symptoms requiring medical attention. The Danish Patient Safety Authority has advised people to avoid both live and dead caterpillars, stay away from nests, and be cautious of leaves or soil under infected oak trees.
Guidelines for Public Safety
To help the public stay safe, health authorities have issued the following recommendations:
- Avoid all contact with the caterpillars, including their nests and the ground beneath infected trees.
- If exposed, rinse skin immediately with lukewarm water and take a thorough shower as soon as possible. Clothing should be washed at a minimum of 60°C (140°F).
- In case of eye contact, flush with clean water. Avoid touching or rubbing the eyes.
- Seek medical attention if symptoms worsen or if there are signs of difficulty breathing.
Outlook and Ongoing Monitoring
Entomologists suspect that climate change, milder winters, and fewer natural predators are contributing to the spread of the oak processionary moth in Denmark and northern Europe. Danish municipalities are now coordinating with national health and environmental agencies to adopt long-term containment strategies.
With the organism now confirmed on both Fyn and Jutland, there are growing concerns that the infestation could expand into other parts of the country unless swift national intervention is implemented. Residents near oak trees are being urged to stay alert and report any signs of nests or infestations to their local authorities.
