Insect Growth Regulator and Drano-like Product in Switzerland?

I'm currently living in Basel, and I have a problem with drain flies / "sewer flies" that I found are breeding in one of my bathroom drains.

In order to fix this problem, I read advice that I should apply a "foaming pipe cleanser" (similar to Draino product in the U.S.) inside the pipes after cleaning out the gunk, and then apply Insect Growth Regulator.

Does anyone know the proper names (in German) or suggested brand names for such products in Switzerland?

For the Insect Growth Regulator, I tried "Insektenwachstumsregulatoren" and the like, but came up with nothing.

Any particular stores you suggest where I could find these?

Thanks in advance. :msnnerd: