I didn't know it, either. I suspect I already went through this exact googling process once before, but it must have been a long time ago because I couldn't remember either the German name of the things or the English one. LOL. I just happened to know that some people call them "daddy long legs" (whereas other people mean a type of spider when they say that), so I had a starting point. XD

They look like GIANT MONSTER MOSQUITOES so the whole "harmless" thing is hard to believe ...