In the last few years, from mid-May to July, oak trees all over the Netherlands are wrapped in red-white warning tape.
This is because of the Oak Processionary Moth (‘Eikenprocessierups’ in Dutch).
The poisonous bristles of these caterpillars are an active defense mechanism and are released when the caterpillar feels threatened.
They can also be spread with the wind and can cause a lot of discomfort to both humans and animals; severe itching is the most well-known consequence.
The caterpillars are mainly spotted in oaks along streets in cities, towns and villages.
The caterpillars also live in forest areas, but here there seems to be a biological balance with their natural enemies.
Infested oak trees can be recognized by silky nests around the branches and the trunk of the tree.
The adults moths fly during July and August.

Caught in my self made moth trap.

In my yard, Hilversum, The Netherlands, 27 July 2019