Abstract: A first object of the present invention is an insecticidal composition comprising: (i) An active substance that is at least one component with adulticidal and/or larvicidal insecticidal activity and/or at least one component with insect growth regulation activity; (ii) At least one synergist which is a hydrocarbon alcohol having between 6 and 24 carbon atoms, linear or branched, saturated or unsaturated or derived thereof or its derivatives, such derivatives being carbonates or esters of such alcohols. A method for insect disinfestation, which includes the exposure of the area of interest or target insects to said at least one hydrocarbon alcohol or derivatives and to at least one active insecticide, simultaneously or within 5 hours, is also the subject of this invention.