There are several known natural compounds shown to be effective at repelling mosquitos.Some possible reasons you may want to consider a DEET alternative; a bad odor, toxicity, skin damage, allergic reaction. A few well substantiated alternative repellents are p-menthane-3,8-diol(Lemon Eucalyptus oil), menthol(Peppermint oil), geranial(Lemongrass oil), and Soybean oil. Using a product containing these alternatives may be a more pleasant and safe experience than using a DEET containing product.