This study evaluated the insecticidal effectiveness of eco-friendly crop protection agents against two major pests of spring onion (Allium fistulosum L.), Thrips tabaci and Spodoptera exigua. Four biopesticides—dill seed oil, paraffin oil, neem extract, and an anthraquinone (AQ) formulation— were compared to the chemical standard, carbosulfan. Both carbosulfan and dill seed oil achieved nearly 100% corrected mortality for both pests across all observation dates, with no significant difference between them (F5,45=441.88,p < 0.001). Paraffin oil and neem extract demonstrated moderate efficacy, resulting in approximately 31-33% mortality, while the AQ formulation had the lowest mortality rate at 3%. For Spodoptera exigua larvae, dill seed oil exhibited a delayed insecticidal effect: mortality was 0% at 1 day after treatment (DAT), increasing to 44.8% at 2 DAT and 51.7% at 3 DAT (F5,45=8.75,p < 0.001). Neem extract and paraffin oil also showed gradual increases in mortality, although these were not statistically significant. Overall, the findings suggest that dill seed oil is a promising eco-friendly alternative and provide valuable insights for developing pest- and growth stage-specific control measures within integrated pest management (IPM) programs for sustainable onion cultivation.