Background: Although use of synthetic insecticides causes excellent control of insect pests, it leads to adverse effects on non-target organisms as well as the environment. The present study determining the chemical composition and insecticidal activities of essential oil extracted from the leaves of rough cocklebur, Xanthium strumarium and its bioefficacy against the castor semilooper, Achaea janata shall show a new dimension in formulating an ecofriendly management strategy towards castor crop. 
 
Methods: Xanthium strumarium leaf essential oil was isolated through hydro-distillation method using Clevenger apparatus and the chemical composition was analysed using GC-MS. The ovicidal and insecticidal activity of the essential oil was determined by dipping and topical application methods, respectively. Larval feeding deterrence and growth inhibitory properties of the essential oil was evaluated through the diet incorporation method.&nbsp; 
 
Result: GC-MS analysis of the X. strumarium essential oil revealed the presence of 14 chemical compounds, of which the majority are the terpenes (94.48%). The LC50 values in terms of ovicidal and insecticidal activities were recorded to be 69.70 &micro;L/mL and 0.30 &micro;L/larvae, respectively. The fifty per cent larval feeding deterrence (DC50) and growth inhibitory properties (EC50) were recorded to be 1.88 &micro;l/cm&sup2; and 213.94 &micro;L/mL, respectively.

Bio-efficacy of Xanthium strumarium L. Essential Oil against Castor Semilooper, Achaea janata L. (Lepidoptera: Noctuidae)