Spider spray containing pesticides and natural oil is the best form of spider repellent. Aerosols contained in spider spray are effective in repelling and exterminating spiders indoors and outdoors.
Application of spider sprays inside cracks, window pains and crevices is an effective way of repelling spiders. These sprays contain pesticides that kill spiders by poisoning and suffocating them. When applied on their webs and nests, the sprays dry up their laid eggs. This prevents the generation of new spiders once the adults ones have been repelled.
Spider sprays are effective when dealing with large spider infestations in basements, garages and secluded areas. Spider sprays have little health risks to humans, which makes them ideal for indoor application. They can be applied in schools, homes and offices to repel spiders that hide behind furniture and cabinets. As stated by About.com, the sprays can also be applied outdoors, in gardens and yards, to kill spiders that hide behind plants.
Spider sprays contain Deltamethrin, a common insecticide from the pyrethroid family. According to the National Pesticide Information Center, the colorless and odorless chemical is the main component used in pest control. It kills spiders on contact by disrupting their digestive and nervous systems, causing their quick death.