Sitophilus zeamais and Prostephanus truncatus are the major pests of maize and can simultaneously infest maize grains during storage. This study aimed to evaluate the effect of interspecific competition on the feeding and reproductive behavior of P. truncatus and S. zeamais over a six-month period. To achieve this, maize grains were simultaneously infested with the two pests at different ratios, representing the following treatments: 25 P. truncatus – 25 S. zeamais, 25 P. truncatus – 50 S. zeamais, and 50 P. truncatus – 25 S. zeamais. A significant increase in the number of S. zeamais offspring was observed compared to P. truncatus. Moreover, S. zeamais caused the highest rates of grain perforation and weight loss. Within the same maize stock, the feeding and reproductive behavior of S. zeamais did not appear to be affected by the presence of P. truncatus. The mixed-population treatment of 25 P. truncatus – 50 S. zeamais caused the most damage, whereas the 25 P. truncatus – 25 S. zeamais treatment resulted in the lowest grain weight loss and perforation rates. These results indicate that interspecific competition influences infestation dynamics, damage levels, and weight losses caused by these two pests.