Tigerfan

To keep flies off of anything you can get a gallon ziplock bag and fill it up with water to where you can close it. Hang it at the opening of a door or window or in this case a bag and they will bug out. When they come around it they see their reflection and it looks bigger than they are. They will cut out running the other way. We have done this for years down here in the summer when we have cook outs and what not. If you can rig you up something to put it in with an opening where you can hang the water filled ziploc you won't have any problems. I would still get some ice on it as quick as possible though.