Organic spraying to control eikenprocessierups has begun

It started this week in several of Maastricht's streets. Organic spraying to control the eikenprocessierups (oak processionary caterpillar). The caterpillar lives on oak leaves and, with its stinging hairs, causes skin irritation and eye infections in humans and animals.

There are thousands of oak trees in Maastricht. They provide coolness and atmosphere in the city, but they are also favoured by the oak processionary caterpillar, the larva of a moth that lays its eggs in the treetops. Once it hatches from its eggs, the caterpillar undergoes a number of moults, reaching maturity in July. After the third moult – somewhere between the end of May and the end of June – the caterpillar develops hairs. These cause skin and eye irritations in humans and animals. It is the reason why people have been committed to control for about 15 years now.

"This control is done entirely organically," says Jean-Pierre Duijsens of Plant Health Services. "We spray the oaks with a bacterial solution. Oak leaves that are then eaten by the oak processionary caterpillar cause the caterpillar to die within a few days. For humans and other animals, the pesticide is completely harmless. Our sprayers carry leaflets with information if people want more information, and we do not spray in certain places in Maastricht. In those places, the Centrum voor Natuur- en Milieueducatie – CNME, has put up boxes for the titmouse bird. Those birds eat the caterpillars and thus provide natural control."

Through a special technique involving electrostatic force, the biological agent reaches high in the tops of the trees. The service has only 3 weeks for the control. "That's why 14 municipalities in Limburg are working together on this. It's quite an operation," Duijsens says, "which becomes even more challenging because of the weather conditions. If it is raining or windy, we cannot spray."
Over the next few weeks, the tractors with spraying equipment will be seen in various parts of Maastricht. "If you have an oak tree in your own garden, please let the municipality know," Duijsens informs. "Then that too can be included."