DEET was developed by the US Department of Agriculture and was patented by the US Army in 1946. DEET works by disrupting the olfactory sense of mosquitoes so they can't find you. A few reports have raised health concerns regarding the use of DEET-containing products especially by children. Other repellents have different degrees of anti-mosquito power. Citronella, permethrin and various essential oils such as soybean, clove, cedarwood, peppermint, lemongrass oils have all been used to repel mosquitoes.
Some people burn citronella candles to avoid mosquitoes.
It may be that burning candles interfere with the mosquitoes' ability to detect heat, moisture or odor. Another chemical used to fight mosquitoes is permethrin, a synthetic form of pyrethrum, a chemical from the chrysanthemum flower. Permethrin is not a repellent, rather it is a neurotoxin that kills bugs on contact. Permethrin should be used only on clothing, not directly on your skin. Clove and thyme oils are effective mosquito repellents when used in high concentration.