Municipalities warn residents about toxic oak processionary caterpillars

Several municipalities are warning people about the oak processionary caterpillar. The caterpillar has hundreds of thousands of tiny stinging hairs on its back, which can cause itching, skin rashes, and irritation of the eyes and respiratory tract in humans and animals.

Due to the warm and dry spring, the caterpillars hatched from their eggs as early as the end of March, Nature Today reported at the time. The insects have been present in the Netherlands since the 1980s. The warnings are coming from municipalities across the country.

The caterpillars live off of the leaves on oak trees, where they have their nests at the bottom of the tree. The grey caterpillars develop orange or red spots later in the season. They move in a long line, hence the reference to a procession in their name.

Most municipalities are asking residents to report any nests they find so that they can be removed. This is done using a suction system. People are discouraged from removing nests themselves because this could lead to the caterpillar’s hairs being spread out through the wind and remaining toxic for weeks.

Leeuwarden has said that it is best for people to make their garden as attractive as possible for birds and insects, of which some are the natural enemies of the caterpillar. These include parasitic wasps, predatory beetles, and ants. “These animals see the caterpillar as food and eat them before they can develop their hairs.”

The number of oak processionary caterpillar nests in Nieuwegein has increased significantly. Last year, 147 residents reported that they had found a nest. Now, the number of people that have reported a nest is at 400. The municipality has put up 300 bird nesting boxes to help with the control efforts.