Indoor residual spraying (IRS) involves applying residual insecticide to potential vector resting sites on the interior surfaces of human dwellings or other buildings. The main aim of IRS is to kill vectors before they are able to transmit pathogens to humans. When carried out correctly, IRS has historically been shown to be a powerful intervention to reduce adult vector density and longevity for mosquitoes, sand flies and triatomine bugs and can reduce the transmission of vector-borne diseases.