Remedies for keeping flies away?

Any remedies for keeping flies away? I often like to keep the door (non-sliding) to my balcony open. The only thing is there is no screen so I hung up a lace curtain that looks pretty and keeps a lot out of the apt. but when the wind blows the flies can get in and then I cannot get them out. Are there any... show more Any remedies for keeping flies away? I often like to keep the door (non-sliding) to my balcony open. The only thing is there is no screen so I hung up a lace curtain that looks pretty and keeps a lot out of the apt. but when the wind blows the flies can get in and then I cannot get them out.

Are there any remedies that you know of to keep them away? I heard that in Portugal they keep plastic bags filled with water up by windows and doorways to keep them at bay and it supposedly works. Anyone have experience with that?

I am open to most anything. Last year I lived in the same complex and only had cluster flies (they like to cluster and hang out on windows)-- they were easy to take care of, I just vacuumed them up with my handheld vacuum and released them outside.
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