Abstract: A wettable powder which can be made up into a sprayable aqueous dispersion for use in pest control to allow an active substance to be applied to a surface to be retained thereon for an extended duration, particularly without undergoing degradation of its properties, comprises the active agent which is an active agent not readily soluble in water and a water-soluble naturally occurring organic product such as a phospholipid having the capacity to serve as a non-polar domain which has high affinity for hydrophobic molecules to keep them in a stable aqueous dispersion.