[Aim]  To clarify the population dynamics of the moths Spodoptera frugiperda and Ostrinia furnacalis on autumn maize crops in Nanchang, Jiangxi Province, and compare the effectiveness of two, different, pheromone traps for adult moths. [Methods] A "W"-shaped five-point sampling method was used to investigate the occurrence of S. frugiperda and O. furnacalis larvae on autumn maize in Nanchang in 2021 and 2022. The performance of tapered and barrel-shaped sex pheromone traps was also compared in the field. [Results]  In 2021, the first peak of the S. frugiperda larval population occurred during the small tassel stage, and the second peak appeared during the tasseling stage. There were also two distinct peaks of adult moth captures in pheromone traps that generally corresponded to larval population dynamics, but occurred about one week later. In 2022, the larval peak occurred from the jointing to the small tassel stage. Captures in tapered and barrel traps peaked during the big tassel and tasseling stages, respectively. The population dynamics of O. furnacalis also exhibited two distinct peaks in both 2021 and 2022. In 2021, the larval population peaked during the jointing and tasseling stages, while the peak of adult moth captures occurred during the jointing and flowering stages. In 2022, the larval peak occurred during the small tassel and flowering stages, but the adult peak occurred during the big tassel and silking stages. Tapered traps significantly outperformed barrel traps in terms of both total moth catch and weekly average catch (P<0.05). A regression analysis revealed a highly significant, positive, correlation between the larval abundance of each species and the number of adults captured the following week (P<0.01). [Conclusion]  The peak of S. frugiperda larval abundance typically occurs during the tasseling and silking stages in autumn maize fields in Nanchang, Jiangxi. Growers should focus on monitoring adult moth dynamics and implementing larval control measures during these periods. Peak O. furnacalis larval abundance occurs between the tasseling and jointing stages, as well as between the flowering and silking stages. Therefore, control measures for this pest, together with continuous monitoring of adult moths, should begin in the tasseling stage. Growers should be vigilant for changes in pest population levels 3-5 weeks after the first peak. The use of cone-shaped traps is recommended for both S. frugiperda and O. furnacalis control, as well as for monitoring adult moth abundance.