Peppermint oil, while unusually fragrant to humans, acts as a repellent to most insects, especially mosquitoes and fleas. You can apply dabs of concentrated peppermint oil to focal points on your skin or clothes, or use a diluted formula to spray over broader areas.
Also on these boards
Peppermint oil--Since the mosquitoes are going to be on overload this season, I need to whip up a batch of this. Keep the mosquitoes away.
DIY Natural Insect Repellent Spray with Essential Oils