A mosquito repellent is a substance designed to keep away mosquitoes, thereby preventing them from biting humans and feeding on human blood. ... Mosquito repellents are available as creams, lotions, oils, and sticks, which are applied directly on the skin.Spray-on insect repellents, for example, simply make people less attractive to the pest. To prevent bug bites from pests like mosquitoes and fleas, the u.S. Centers for disease control and prevention (cdc) recommends using u.S. Environmental protection agency (epa)-registered insect repellents.