Abstract: Impact of new crystal compound 2, 5-diacetoxy-2-benzyl-4, 4, 6, 6-tetramethyl-1, 3-cyclohexanedione on feeding physiology, developmental indices and quantitative changes in haemolymph protein on the larvae of armyworm, Spodoptera litura was studied. The novel compound was isolated from the leaves of medicinal plant, Syzygium lineare. The percentage of feeding physiology parameter such as Consumption Index (CI), Growth Rate (GR), Approximate Digestibility (AD), Efficiency of Conversion of Digested Food (ECD) and Efficiency of Conversion of Ingested Food (ECI) and weight gained by the larva was decreased significantly (p<0.05 by LSD). The developmental indices such as time taken for pupation, pupal weight, adult longevity, eggs laid per moths and the percentage of egg hatchability were also decreased significantly (p<0.05 by LSD) compared to control. Statistically significant (p<0.05 by LSD) reduction in total haemolymph protein was recorded at 100 ppm concentration of crystal compound treated larvae. This compound has potential to serve as an alternative botanical pesticide in the management of agricultural important filed insect pests.