Basil as an insect repellent
Basil is said to keep away flies and to be one of the few herbs that gives off its scent without someone brushing it or crushing it. I doubted both of these and certainly my small basil plant on the kitchen window was no deterrent at all to the clouds of flies each summer. Then I brought a giant bucketful of basil indoors that I was planning to sell to a restaurant, and stuck it by the door.
The flies stopped winging through the door, even when I put a roast lamb leg in the oven!
Basil is a slightly effective fly repellent when rubbed on the skin; it also helps repel mosquitoes (there are more effective repellents) if you don't mind smelling like a tomato salad.
If you are going to try basil as a fly repellent, remember - you need lots, just like you do when you eat it.