An oaks' procession

While geocaching in solitude in a remote location somewhere in the Netherlands I strode through a small patch of oak.
I stopped. The trees made a funyy noise. And that's something funny indeed, because trees tend to be silent, except in stong winds or downpoor. So I listened. I must be loosing it, I thought, it sounds like nibbling. En masse nibbling. Now cows, sheep. Hmm.
And then I saw it. This one secluded caterpillar slowly crawling up the tree. Given the sound there must be others. I decided to hold my breath and take a number of pictures. Like this one,
Believe it or not, I did not see his friends striving upwards, I only noticed them on my laptop at home. Wow, An actual procession. Just look at those hairs, those tiny sources of itchyness. Now I know why they are called oak Processionaries. A catchy name.