Life-history theory predicts that individuals must allocate limited energy among growth, maintenance, dispersal, and reproduction, creating trade-offs between flight capability and reproductive investment. In insects, wing polymorphism provides a useful system to examine these trade-offs because the development and maintenance of flight muscles require substantial energetic costs that may reduce resources available for reproduction. While such patterns are widely documented in females, the reproductive consequences of wing dimorphism in males remain less understood. The praying mantis Amantis nawai, which exhibits flightless females and wing-dimorphic males, offers an ideal model to investigate male-specific allocation strategies. We compared reproductive traits, mating behavior, development, and lifespan between micropterous and macropterous males. Micropterous  males possessed significantly larger testes with more seminiferous tubules and exhibited longer copulation durations than macropterous males, suggesting greater sperm transfer per mating. However, mating frequency and mating intervals did not differ between morphs, indicating that micropterous males enhance reproductive output through increased ejaculate investment rather than increased mating rate. These results suggest that reduced investment in flight structures allows greater allocation of energy to gonadal development and fertilization success. Life-history traits further revealed differences in survival. Developmental time did not differ significantly between morphs, but macropterous males showed shorter adult lifespans, whereas micropterous males lived the longest, even exceeding females. This pattern suggests that the energetic demands of flight muscle maintenance may directly reduce longevity. Overall, our findings demonstrate that wing polymorphism in male mantids reflects alternative reproductive and survival strategies shaped by energetic trade-offs. By integrating morphology, physiology, behavior, and life-history parameters, this study highlights the role of flight–reproduction trade-offs in shaping male reproductive tactics and provides new insight into the evolution of polymorphism in insects.