... also known as oak galls - or galæbler in danish.
I took a round, alongside the border of our woods, bringing my youngest, and a small basket, conveniently hanging on my arm. The basket, that is. But both very practical to bring. My little one has an ability for spotting oak galls that I very much appreciate. His (lack of) height is also an advantage for this task.
In order to find them, you need to look at the underside of the leaves of oak trees. Positioning yourself with your back to the bole/trunk makes spotting them a lot easier. Also, your neck can benefit from this, avoiding repercussions from abnorm neck craning while searching.
Well, these two pictures above are, admitted, a stroke of luck. Normally there aren't that many galls at a single twig. The cynipid gall wasp laying her eggs here, must have been in some sort of frenzy.
Just about now, is a good time to go hunting for oak galls. You can find them all year round, after leaf fall too, but then it's more like finding a needle in a haystack.