Surround a door with a PVC pipe filled with water, It will keep many flies and mosquitoes out of your house.

CaptionPictures of the pipe door and how a fly sees the potential drops of waterDiscouraging Mosquitoes and Small FliesMaurice Cottrell presents what is a quite remarkable effect. He says: "What it is, is a church door in Ireland, surrounded with a white plastic pipe filled with water." Maurice considered the effect and his opinion is that small flies can be injured by raindrops and so they have learned to avoid them. A falling raindrop has an electrogravitic effect due to the hydrogen atoms in the water, and flies which can see in the ultraviolet spectrum, can detect that effect around water and their instinct makes them avoid water – whether falling as droplets or not. Large bluebottle flies do not seem to be affected, but there is a definite effect with smaller flies. If a doorway is surrounded with a 1-inch (25 mm) diameter plastic pipe filled with water, as seen in the picture above, then Maurice believes that the resulting effect is like this: Here, gravity waves spread out from the water and create an effective barrier all the way across the doorway, discouraging the smallest flies, including midges. Obviously, any opening can be surrounded with a water-filled pipe, and not just doorways. This is a method which could well be useful where serious diseases are carried by mosquitoes.My next step is to make 1 ft. pyramids and cubes out of PVC pipe filled with water, to protect food from flies when it's on the table. Like those bug screen food covers.