Burning citronella incense sticks or citronella oil candles repels flies as well as mosquitoes. In addition, there are a few citronella oil preparations that can be applied directly to the skin as a fly and mosquito repellent.
These types of repellents need to be used more often than other synthetic brands of repellents. Citronella oil is classified as an essential oil that is extracted from different species of lemon grass known as Cymbopogon. This oil is considered to be a non-toxic biopesticide. There are various fly sprays that contain citronella and natural pyrethrum blends that are also used to repel flies effectively.