Outdoor insect barrier sprays are a professional product that you can use yourself. Follow the safety tips on the package and before you start, put on rubber gloves. If you’re going to be spraying up high, wear safety glasses and a face mask. Spray the insecticide around the outside of your home and on your windows and doorways. It helps stop ants, cockroaches, spiders, fleas, paper-nest wasps, flies and mosquitoes from entering your home.