Fifteen dihydro-13-agarofuran sesquiterpenes from different species of Celastraceae were assayed for possible antifeedant activity against Egyptian cotton leafworm Spodoptera littoralis (Boisduvai) larvae, using the leaf disk method. The activity was evaluated by calculating the feeding ratio (FR) from the relationship between the consumed areas of treated disks (CTD) and control disks (CCD) at regular intervals; for comparison purposes a FR50 (50% of CCD) was established. In general, the compounds exhibited moderate to low antifeedant activity. Compound 4 (9β-benzoyloxy-8α,2-methylbutyroyloxy-1α,6α,15-triacetoxy-4β hydroxydihydro-13-agarofuran) was the most active of the series. At a dose of 0.1 μg cm⁻², this compound gave a FR50 = 0.23 and in non-choice test conditions, nearly 100% leaf disk protection.