Screed heating phase and extreme tiny fly infestation???

We are building (or having built) our dream house and have had a crazy problem for a few days now.

The house is already plastered and painted on the outside
All the windows are installed
Roller shutter boxes are still empty
All interior rooms plastered
Screed on underfloor heating all laid
We are currently in the heating-up phase and ventilating a lot

Now, for about 5 days, on all the windows INSIDE there are tiny, about 1-2 mm small black mini-flies in huge numbers!!!
If you wipe them away with a cloth, they are gone immediately... or so you think.
As soon as you close the windows, a few minutes later there are more and more again.
This happens both on the ground floor and upper floor.

We have already read a lot on the internet about larvae in flowerpots and fruit and so on... none of that helps.
We are still under construction and there are neither plants nor fruit nor furniture in the house.
And we are at a loss on how to get rid of these pests???

Has anyone had this problem before?
Does anyone maybe have an idea??
Is it due to the current weather—humid, warm, stormy?
Or the adjacent meadows and forest?
We are grateful for any tip!

Best regards

Completely normal ... nature ... glass with oil wine mix

um..... we now also live in a small town on the outskirts, then there is one more house and then lots of meadow and have never had that problem ????

What is meant by - Nature - is that supposed to be standard now ????? ops:
That would be really mean... that amount and then living in it ... well, nice.....

Thanks for the tip - we will try it.

Question - what kind of mini-flies are those?????

um..... we now also live in a small town on the outskirts, then there is one more house and then lots of meadows and have never had this problem ????

What is meant by - nature - is that supposed to be standard now ????? ops:
That would be really nasty... this amount and then still living inside ... well, lovely.....

Thanks for the tip - we will try it out.

Question - what are those mini flies then?????

Completely normal fruit flies. Something attracts them.

Question - what kind of mini flies are those then?????

Hello Skorpi-Haus

take a photo. If possible in macro.
Fruit flies (2-3mm, can fly well and you can clearly see the wings. Maybe there is some fruit fermenting somewhere in an opening. Remove the fruit, the flies disappear.

Steven

Hello

or they are the so-called storm flies (lacewings). They are a bit smaller, black and elongated. They don't fly quite so skillfully.
Vacuum them up. Hang a blue sticky tape. It attracts the critters.

Steven