Abstract: Psocids, as a common pest population in the stored grain, are difficult to control in a field granary. Detecting the dynamics of the psocids population is the base of integrated pest management. Since the differences in sensitivity of various detection methods are significant, it is very important to know the relationships of these methods. Probe trap, corrugated-plastic dish trap, 2-layer corrugated-cardboard trap, 3-layer corrugated-cardboard trap, and manual sampling sieving method were used to detect the population density of Liposcelis bostrychophillus Badonnel in the top layer of the grain mass. The results were as follows: based on the population density (d) of L. bostrychophillus detected by the manual sampling sieving method, 1) when d≤5 individuals per kilogram (I/kg) or 6 I/kg≤d≤10 I/kg, the detection method with 2-layer corrugated-cardboard trap could detect L. bostrychophillus earlier and more than the other methods. 2)when 10 I/kg< d≤30 I/kg, both probe traps and manual sampling sieving method could detect L. bostrychophillus earier than the other methods. The number of L.bostrychophillus detected by probe traps was maximum in all methods. 3)when d> 30 I/kg, the manual sampling sieving method was the most effective method. The primary occurrence of L.bostrychophillus was in the last period of May in the top layer of the grain mass. The peak occurrence started at the beginning of June and maintained for about 2 months, and then the pest density decreased. It was found that the pest density was higher in the southwest and central part of the grain mass, followed by that in the northwest and southeast part, and the least in the northeast part.