Insect protection roller blinds do not keep insects away

Yup! The best solution and problem solved!

Dear ones, thank you for the responses. I have probably expressed myself poorly: I need a solution for the fly screens. I have spent over 2500 euros on 8 fly screens for the entire house, and they do not keep these flies away. THAT is my problem. Can I seal, retrofit, or replace them? The pest control man is always an option for me, but that should only be the last resort. Thank you all!

The pest controller is not a last resort. He probably knows more about insect protection than your supplier and can independently tell you whether the fly screens are defective, incorrectly installed, unsuitable, or modifiable... I can understand that you want to protect your investment, but I would find it surprising if that were more important to you than a fly-free house.

Allow windows?

I can understand the OP well. She invested quite a bit of money in the fly protection blinds and yet some still get in and even nest, if I understood correctly. So I would also be a bit annoyed if flies still manage to make their way into the house. That device was meant for that. There must be something wrong with the design. It’s up to the manufacturer or whoever installed it. Comments like "open the window" or "call the pest control" don’t really help. Maybe briefly call pest control. But do they know anything about the construction? Do they provide more advice? I don’t know about that. They only eliminate the insects present, which isn’t necessary. They should live, just not in the house.

But does he know anything about the construction? Does he do more in consulting?

Yes and yes. Prevention is a core competence of pest controllers. Who else comes up with concepts, for example, for bakeries? Take a local expert and not a franchise xyz or chain. Firefighters have knowledge about fire protection. Doctors have knowledge about healthy living. ...