Insects and worms are attracted to decaying fruit. It is said that eating garlic and taking a potent B-Complex supplement will repel mosquitos. They keep insects IN as well as out. The only screens you'll need are those on open windows facing neighbors with animals, with uncovered garbage, or with water problems. A lighted room with an open window will also require a screen at night.
Screens are great barriers to free air flow and are little better than closed windows.
Also, small or baby insects often get through the screen to the light. So, it's better to keep the windows to lighted rooms closed at night. Don't worry about the insects accumulating on the outside of the window. Let them bang their heads against the glass while lots of bugless air is coming through the screenless open windows of unlighted rooms. The occasional insect will of course enter your home, but will quickly notice the lack of animals, food, and water and soon be on its way.