Serial dilution is continued using the above equation or a 1:1 dilution for the next 10-12 concentrations is done consecutively from the highest to lowest concentration The cap of the vial is secured with parafilm to minimize evaporation. The prepared insecticide dilutions are stored in a refrigerator(4 °C) or freezer(preferably -20°c). After preparation of an insecticide, the pipettor tips are replaced and disposed of properly