As everyone has said, Thermacell if you are sitting still and it is not windy. Works great in a blind during turkey season.

I use the Repel Brand of spray, available at Walmart. I use the Permanone on my clothing and the 40% deet on any exposed skin. I am sure I must own stock in the company by now. lol Not sure if it works on deer flys as I never see them. lol Doh, it must. But it workd wonders on ticks and chiggers. Always make sure to cover your pants fly well, as unzipping to go to the bathroom gives them an open door to get in.