Neem oil is a great natural insect repellant that is extracted from the seeds of the Neem tree. The oil itself is very viscous and to appy neem oil you need to dilute it inside of a sprayer.
Diluting Neem Oil
You should use 1.5 teaspoons of pure high quality neem oil per quart of water or 2 tablespoons per gallon of water. Its much easier if you use slightly warm tap water, its difficult to mix neem oil with cold tap water.