Hi Marvado,
first of all nice grow so far :)
In Northwest Europe, including the Netherlands, one common caterpillar that can be found eating cannabis plants is the Small Tortoiseshell Caterpillar (Aglais urticae). This caterpillar is known to feed on various plants, including cannabis, and is often found in gardens and natural areas.
Remember that not all caterpillars are harmful to cannabis plants. Some may not cause significant damage, while others can be more problematic. Identifying the specific caterpillar species is key to determining the appropriate course of action for managing the issue effectively and responsibly.
U just have to identify the right ones and then go for neem oil foliar spray or something else with milk. Spray it on all leaves from both sides to get rid of them. Maybe repeat it after 2 weeks again.
If you need further help feel free to follow and from me a DM :)
Have fun and good luck!!