<p>The fall armyworm (<i>Spodoptera frugiperda</i> J.E. Smith) has recently become a destructive invasive pest in India, with maize being the most severely affected crop. Farmers rely predominantly on chemical control, yet continuous exposure raises the risk of changes in susceptibility. To evaluate the susceptibility status, multi-generational bioassays were conducted during 2022–2023 using second-instar larvae. Leaf-dip assays were performed using three key insecticides: emamectin benzoate, spinetoram, and flubendiamide. Probit analysis was used to estimate LC₅₀ values, fiducial limits, slopes, χ² values, and resistance ratios over four consecutive generations each year. Among the tested molecules, emamectin benzoate exhibited the greatest efficacy (LC₅₀: 0.031–0.167 ppm), followed by spinetoram (0.264–0.456 ppm) and flubendiamide (0.526–1.251 ppm). Resistance ratios remained consistently low (&lt; 1.41), with stable regression slopes and non-significant χ² values, indicating reliable concentration-response relationships. Notably, no biologically significant resistance development was detected, despite minor increases in LC₅₀ values indicating slight shifts in susceptibility. This investigation presents the first multi-generational evidence from India confirming the effectiveness of emamectin benzoate, spinetoram, and flubendiamide. The outcomes highlight their relevance in integrated pest management, while also underscoring the need for regular resistance monitoring, prudent rotation of chemistries with different modes of action, and integration of biological control measures to sustain long-term efficacy.</p>