Efforts to control malaria focus not only on medical therapy to prevent infection and treat people who are infected, but also on insecticide spraying, and the use of insecticide-treated curtains and bed nets. The insecticide strategy relies on spraying the walls of the houses in which people live, to kill the insects that have just fed on people before any malarial parasites can mature or be transmitted to others. Bed nets treated with insecticide protect both the person sleeping underneath them and others in the community, as mosquitoes that rest on the nets are killed.