Talk about a real pest, flies drive me up a wall and their are times when they can get way out of hand.
Of couse the first thing to do is to try to figure out why you're getting flies. Most of thet time it's from animal food or a liter box that hasn't been cleaned fast enough. When you notice those big black flies that seem to be coming from every direction it's usually a sign of a dead mouse or some kind of dead animal in the area. Unless you're dealing with fruit flies and that's a whole different discussion.
My favorite way to knock a fly down fast is with hairspray, the cheaper the spray the better. But you asked about plants or oils.
There are a lot of plants that will repel flies, like; pennyroyal, eucalyptusm mints or cloves. You'll need to place the leaves in a muslin bag and pound them to release the oils. You can also plant sweet basil or rue near your doors or deck, mint is also great to plant around your house, it will also chase any mice that are thinking about visiting.
You can also put some eucalptus, peppermint or oil of cloves essential oils on a cotton ball around your house or even near you when outside will help chase any flies away. It sure beats trying to use all that nasty bug sprays around you and your food.
