General information about the oak processionary caterpillar
The oak processionary caterpillar: what exactly is it?
The oak processionary caterpillar is the larva of a moth. That butterfly lays its eggs mainly in the tops of oak trees. There the eggs overwinter. They hatch from mid-April to early May. After molting several times, groups of caterpillars come together. They form large nests on the trunk and side branches of the oak tree. At night they go in procession in search of food in the tops of the tree, hence the name. Large groups of processionary caterpillars can eat a tree completely bare. The caterpillars molt three times, after which they develop fire hairs. The fire hairs cause health problems in humans.
Where did the oak processionary caterpillar come from, a few years ago we never had it?
About 30 years ago, the caterpillar was first seen in the Netherlands. There are many oaks in our country, so there is a lot of food for the caterpillar. In recent years the number has grown explosively, probably because the conditions were favorable.
How many fire hairs does an oak processionary caterpillar have?
Each fully grown oak processionary caterpillar has about 700,000 invisible fire hairs with arrow-shaped barbs.
How do the fire hairs spread?
Distribution of the fire hairs is by air. Wind brings hairs as far as a hundred meters from the nest.
How do I recognize a nest?
Oak trees with oak processionary caterpillars can be identified by spherical, white-gray nests on the trunks or thicker branches. The nests are dense coils of shedding skin with fire hairs and droppings.