After an insecticide treatment, either the gauze or the whole watchglass covered with gauze is replaced to avoid contamination of new batches of test insects with the previous insecticide. Twenty-four hours after treatment, insect mortality is recorded. A convenient way is to use Excel to create a data sheet as illustrated in Appendix B. Moribund insects are considered dead. The mortality count is repeated every 24 hours for up to 5 days after treatment in some insecticide groups, such as with insect growth regulators(IGRs). From these data, LD50 values are estimated using the PoloPlus probit program(to be described in Chapter 6) and will be recorded in ng/g body weight of the insect.