The invention provides aqueous pesticidal concentrates comprising at least one colloidal solid, a dispersed emulsion phase comprising at least one substantially water-insoluble pesticidally active ingredient, which is either itself an oily liquid comprising the oil phase, is a solid but is dissolved in an oily liquid present in the oil phase, is a solid and is dispersed within the oil phase or is present as a colloidal solid adsorbed to the liquid-liquid interface between the continuous aqueous phase and the dispersed oil phase and at least one Ostwald ripening inhibitor.