You can take a ziplock gallon bag fill it half way with water. Then hang it in the door way or by a door way. The reflection that the fly sees will cause the fly to turn in another direction. You can also use a bounce dryer sheet. It is said to keep fly out also. They don't like the scent. They also say to put a bounce sheet and put it in the belt loop of your short or pants to keep mositquos off. You can also use a bounce sheet to dust your TV and electronics to keep dust off electronics.