Photo: Shutterstock Many municipalities use bacterial preparations and nematodes to tackle the oak processionary caterpillar. The preparations, which contain bacterial toxins, also kill the caterpillars of about 100 other species of moths that are on oak trees around now.
According to Wallis de Vries, the use of organic preparations has really taken off, with two out of three municipalities using such treatments. ‘That’s worrying. The preparations are even being used in the countryside.’ The professor also has doubts about the effectiveness of the preparations. ‘This has never really been researched.’
Wallis de Vries says a more uniform approach is needed. ‘We sent a letter to the Agriculture minister, Carola Schouten. A more cohesive policy and better monitoring are required.’