Hi all. I'm so embarrassed to be writing this but I have a serious fly infestation and can't seem to find the source! We have tons of small flies on the windows at the back part of our house. I hoover them off (yes there's that many), turn my back and when I look back round there's about 4 more on there and then more. My house plants have been moved outside, I've poured vinegar/bakingsoda/salt mix down the drain followed by hot kettle water and I don't have any food out. The kitchen was deep cleaned last week so there's no old rotting food. I have them in the bathroom and they're all in the bath and round the window and in our second bedroom. I don't know if they're coming from the drain as the sil is next to the bath and the window in the kitchen is next to the sink. I can't seem to find the place where there is a lot of them (the source). They're just round the windows. I'm honestly at my wits end, I hate them and want to get rid of them but don't know how! Any tips/help would be greatly appreciated! The pictures attached I had just hoovered the window 10 minutes before taking it.