We investigate the dynamic behaviors of a stage-structured pest population model with birth pulse and impulsive spraying pesticide at fixed time.Using the discrete dynamical system determined by the stroboscopic map

we obtain an exact 1-periodic solution of the system which is with Ricker function and obtain the threshold conditions for its stability.We conclude that the best time of spraying pesticide is at the end of the season

that is before and near the time of birth by showing that the time of spraying pesticide has a strong impact on the number of the mature pest population.