You aint gonna need an expensive weapon.
You aint gonna need a fly spray, a chemical insecticide that comes in an aerosol can that is sprayed into the air to kill flies.
What you need is a blank CD and a piece of string! Yup.... just that.
Very economical, not harmful, not toxic.
I asked the stall assistant why hang the CD that way. She answered me... the flies want to hear the songs too...