In this study, a mathematical model is made to estimate the median lethal concentration or dose (LC₅₀ or LD₅₀).  The model is based on the data of different insecticide groups, where each one is represented by the effect of three insecticides over different orders of insects by using different application technique. The trend of change of the LC₅₀ or LD₅₀ is observed among the insect life cycle for each group of insecticides. It is shown that for an insecticide group, there is a clear trend for the change of the LC₅₀ (or LD₅₀) when going from an age stage to another. That trend is simulated for each group to predict the LC₅₀ or LD₅₀ at an age stage by knowing it at another stage and method of treatment used.