Katydids use species-specific sound signals for conspecific recognition over distance. These sound signals aid in species recognition in the field. Predation and environmental variation have documented effects on katydid activity in the neotropics. This study investigated the effect of the three environmental variables, viz., ambient light, temperature, and relative humidity, on katydid activity. Two sites, one in Northeast India, and the other in the Western Ghats were monitored across five years between 2015-2020. Both sites had tropical climates with distinct post-monsoon wet and dry seasons. A total of 537 encounters through psychoacoustic monitoring were used for the analysis. We did not observe any effect of temperature or relative humidity on katydids’ activity. Peak katydids’ activity was recorded near the new moon (Rayleigh test, Z=146.722, p<0.001) indicating effect of lunar light on acoustic signalling. While the overall activity peak is closer to the waxing phase, a comparison between ecosystems suggests that the activity peak is most closely associated with understorey habitat compared to grasslands. High ambient light may increase the predation probability for acoustically active katydids due to insectivorous bats. Our results suggest a role of environmental conditions in signalling behaviour among the palaeotropical katydids than previously expected.