BACKGROUND As a result of climate change, we will have to deal more and more often with the consequences of the oak processionary caterpillar. CASE DESCRIPTION In June, we saw a 6-year-old girl with a severely itchy rash all over her body. The rash had developed a day after school and consisted of erythematous papules on an erythematous base. Several other children at the school were suffering from a similar skin rash. The girl also seemed to have a bad cold. We diagnosed 'oak processionary caterpillar dermatitis'. It turned out there was indeed an oak processionary caterpillar nest at her school. The nest was removed. We prescribed cetirizine oral solution, followed by triamcinolone cream, after which the itch and skin rash disappeared. CONCLUSION The oak processionary caterpillar can cause a lot of symptoms in the period from April to July, including skin rash and eye and upper airway symptoms. The symptoms are usually self-limiting and automatically disappear within 2 weeks. In case of severe itching, menthol-based creams, topical corticosteroids and antihistamines may be prescribed.