I have Seitz and the fly screens are dreadfully.
I blocked up the vents and did all the tricks but in places like Brazil and Amazonia they delayed the insects by mere seconds. They simply get round the sides.
My solution was to make additional fine mesh screens that have a magnetic ribbon perimeter. I then stuck magnetic ribbon on the window frames inside.
The new insect tight screens go over the open window in seconds.
Nothing gets in now
Neil