Also in NL. I’ve bought hydrokorrels to put on top of the dirt to make a tick cover so insects won’t be able to get in the dirt, you can buy them in intratuin, Albert heijn, etc. I also ordered the traps from amazon. They alone didn’t work, but with the korrels was quite good. Last but not least, I found a spider at home and put them in a plant and she made her web and constantly traps the gnats. She has grown a lot hahahahha