[Aim]  This study aims to gain an understanding of the population dynamics of adult Monolepta hieroglyphica in maize fields in the Shenyang area. The findings will establish a foundation for pest monitoring and the development of effective control strategies. [Methods]  During 2020 and 2021, maize fields located in the Shenbei District of Shenyang City were monitored periodically from germination until the harvest stage (mid-May to late-September). Population dynamics and spatial distribution were investigated as follows: M. hieroglyphica were counted using a five-point sampling method to determine the number and distribution on different parts of the plants after adults being found in the maize fields, and the adult sex ratio was investigated. A fixed number of adults were collected from the weeds surrounding the maize fields, the sex of the adults was determined. [Results]  In 2020 and 2021, adult Monolepta hieroglyphica were first observed in the Shenyang corn (vegetative 12 stage) fields on June 30th and July 9th, respectively. Peak insect densities were recorded on July 30th and August 4th (rapid filling stage), with (741.25±47.63) and (337.5±67.69) individuals per hundred plants, respectively. By the end of September, no individuals were seen in the corn fields while a small number of adults remained in the weeds at the field edge. There was temporal variation in the spatial distribution of adults on corn plants at different growth stages of maize. at different growth stages of maize. In early July 2020, over 47% adult M. hieroglyphica were found on the lower leaves. In contrast, 40%-70% of adults were found in the upper leaves during late July to early August, with a spike in females accounting for 54.05% of the distribution. In mid-July 2021, 59.52% of adults were found on the middle leaves, and in late July, 40%-60% of adults were distributed in the upper leaves. A spike in females in early August accounted for 53.46% of the adult distribution. The male-to-female ratio (♀/♂) was 1︰4.88-1︰0 in 2020 and 1∶4.56-1∶0.25 in 2021. [Conclusion]  In 2020 and 2021, adult M. hieroglyphica first appeared in the Shenyang corn fields in late June to early July. The population peaked in late July to early August, then sharply declined with no individuals remaining by mid to late September. The spatial distribution of adults on corn plants was relatively stable at different growth stages of maizes. The population was primarily distributed in the lower leaves before the tasseling stage, with spikes in the female population during the silking to the milk stage. As the dough stage, the adults tended to be distributed in the middle to upper leaves. Male insects dominated higher proportion vegetative 12 stage to rapid filling stage. However, after the population peaked, the proportion of females gradually increased until they were the majority.