Sumitomo Chemical has a long experience in the formulation of superior insecticide aerosols. They consist of a solution of insecticide in a pressurised container; the pressure being derived from a liquefied propellant. As the liquid is released through a system of valve an actuator a fine aerosol spray is produced by mechanical break-up of the solution. The ratio of propellant to solvent in the container, together with the characteristics of the valve and actuator determine the droplet size of the spray and determine its suitability for use in controlling flying or crawling insects.