Improved targeting of flying insects with insecticides and apparatus for charging liquids

摘要

A method of killing flying insects which method comprises spraying into the air in which insects are flying liquid droplets of an insecticidal composition, a unipolar charge being imparted to the said liquid droplets by double layer charging and charge separation during spraying, the unipolar charge being at a level such that the said droplets have a charge to mass ratio of at least +/-1x10-4 C/kg. An aerosol spray device which is capable of imparting a unipolar charge by double layer charging and charge separation to liquid droplets of a composition sprayed therefrom has a spraying head in the form of an insert in an actuator, the spraying head having a bore through which liquid is expelled having an outlet, preferably with a tortuous periphery, having an L/a ratio of at least 8 (preferably at least 10) where L is the length of the periphery defining the bore outlet in mm and a is the cross-sectional area of the bore outlet in mm2 and the apparatus being constructed such that the droplets are expelled from the spraying head at a flow ratio of at least 0.4 (preferably at least 0.5) grams per second and have a charge to mass ratio of at least +/-1x10-4 C/kg.