Introduction: Plant-based knowledge has been used for generations for personal protection from various mosquito species. The notion of applying such traditional perspectives in vector control research has received extensive attention in recent years. Unlike other common patterns, the present investigation has tried to explore the augmented production of reactive oxygen species (ROS) in response to Stachytarpheta jamaicensis exposure with special inference on larvicidal potential, mode of action of phytochemical compounds, and oxidative stress. Methods: The larvicidal potential was determined as per the WHO protocol. Ultraviolet-visible spectroscopy was used to determine the excessive production of ROS. GC-MS was employed to characterise the phytochemical constituents. The statistical analysis was done by using SPSS version 24.0.0. Result: The acetone extract has been found to exhibit a maximum range of toxicity in terms of larvicidal potential and reactive oxygen species formation. Among the 40 phytochemical elements characterised, Cyclopropane, 1,1,2,2-Tetramethyl; Phenyl-Acetonitrile; Pyranone; Tetradecene; Neophytadiene; Mome Inositol; Monocrotaline; and Squalene may be responsible for the augmented production of ROS in the Culex quinquefasciatus. Conclusion: The phytochemical elements in Stachytarpheta jamaicensis displayed extensive toxicity and inhibited the normal development of Culex quinquefasciatus mosquitoes by augmented production of reactive oxygen species, indicating its prominent role in oxidative stress.