The diamondback moth, Plutella xylostella (L.), is a major pest of cruciferous crops worldwide, and widespread resistance to conventional insecticides has intensified interest in plant-derived alternatives for its management. In the present study, ethyl acetate extracts of six plant species viz., Azadirachta indica, Nerium oleander, Plumeria rubra, Sesbania grandiflora, Swietenia macrophylla, and Tagetes erecta obtained through Soxhlet extraction were evaluated at 5% concentration for larvicidal toxicity, larval weight reduction and growth indices against P. xylostella under laboratory conditions with azadirachtin 1% EC (2 ml/l) as a treated check and solvent and untreated checks for comparison. Among the six extracts, S. grandiflora and S. macrophylla exhibited the most notable insecticidal activity. At 24 and 48 h post-treatment, larval mortality caused by these two extracts and the treated check was statistically comparable. By 72 h, the treated check recorded the highest mortality (66.67%), followed by S. grandiflora (56.67%) and S. macrophylla (53.33%), with no significant difference among them. Larval weight did not differ significantly among ethyl acetate treatments until day 5, after which S. macrophylla (0.36 mg) and S. grandiflora (0.47 mg) recorded reduced larval weight compared to the untreated control, while the treated check showed the lowest weight (0.29 mg) and proved superior on days 6–7, with complete larval mortality by day 10. On day 10–11, S. grandiflora recorded the lowest larval weight (1.13 mg), even showing weight loss, and outperformed S. macrophylla (1.35 mg), against 4.96 mg in the untreated control. Pupation was delayed by one additional day in S. grandiflora relative to other treatments. The larval growth index was markedly lower in S. grandiflora (1.86) and S. macrophylla (2.09) than in the untreated check (9.39), with Howe's growth index similarly reduced (0.09–0.10 vs. 0.13). Larval-pupal, pupal weight, adult weight, emergence, and developmental indices ranged narrowly across treatments. Suitability and antibiosis indices were lower in S. grandiflora (0.72 and 5.06) than S. macrophylla (0.80 and 5.60), indicating stronger antifeedant and growth-disrupting activity. These findings confirm the potential of S. grandiflora and S. macrophylla ethyl acetate extracts as eco-friendly botanical alternatives for integrated management of P. xylostella.