An insecticide solid or particulate is produced from a phosphoroamido(di)thioate insecticide such as acephate. The particulate insecticide is formed by melting the insecticidal solids in a substantially oxygen-free, and preferably moisture free, atmosphere to prevent oxygen entrainment in the resulting melt to inhibit later degradation upon storage. The melt is formed into granules, extrudates, prills, flakes, shaped briquettes, or other shapes as desired.