For whatever reason, Europe lacks screened windows. Most places also lack air conditioning. So when the weather gets warm (warm is relative - let's say 70 degrees) windows are opened and fresh breezes blow through homes.
Open windows without screens invite not only cross breezes but house flies. In rural areas where one lives with horses and cows all around, it means lots of house flies. You know that annoying fly or two that makes it in to your house as you come and go? Multiply it by 12 and have them all prefer your kitchen.
When it is not pouring rain and 50 degrees in July, we can have some lovely temperate days - partly cloudy with temperatures in the 70s. This gives rise to the debate to open up the house to enjoy the weather or keep it closed to avoid lots of flies.
We do have several fly control systems in place. We have an outdoor fly trap. We have an indoor bug zapper - this works better on our other flying visitors, as the flies don't seem to be attracted to the light. Kyra is often willing to go on fly swatting missions a couple of times a day. Dobby is also helpful - he tries to catch the flies and when he does he eats them - I've decided to find this helpful rather than gross. I've ordered an indoor fly trap from Amazon which I expect this week. I hope it helps. I also attempt to keep things as clean as possible and not leave any food out anywhere to attract flies. Kyle, Allen and Kyra aren't quite as scrupulously clean as I would prefer.
Even with all this, we generally have 4 flies buzzing around at any given time. This started about a week ago and I expect it to last until mid to late September. A fact of life that I could let really bother me or one I could just say, "Well, that's life in the European countryside." Most days I try to just let it go.
Next summer though, I am looking forward to my screened windows and doors back in Virginia.