I have a problem with a nesting of flies in my window screen tracks every year. My large picture window in parlor I found was loaded the whole length of the track with a straw like nesting of maggots, and not little ones, they were large.
I know they were flies, because the window became loaded with flies when they hatched. I cleaned the track out and washed the windows and track. No food of any kind was located near windows. It happens in my bathroom window also. The nests get so thick the window screen won't close.
Is there a web site to show how flies are created? We installed $13,000 in windows in the year 2000 and it has been happening since then.