Methanolic extract of Artemisia annua L. were evaluated on growth and nutritional efficiency of lesser mulberry pyralid Glyphodes pyloalis (Lepidoptera: Pyralidae) in laboratory conditions (24±1 C, 75±5% RH and 16 L: 8 D). Feeding deterrence index was evaluated by a choice test method on< 24 h fifth instar larvae with 5, 2.5, 1.25 and 0.625 percent of the extract. The result indicated that increasing the concentration resulted in higher deterrence. The extract retarded larval growth significantly (EC50= 3.63%) and also showed significant effects on the relative growth rate (RGR), efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), approximate digestibility (AD) and consumption index (CI). Lipid, protein and carbohydrate in treated insects were significantly reduced compared to the controls. Hence, methanol extract of A. annua could be considered as a strong deterrent which also affects the biochemical metabolism of the target pest. Methanol extract of A. annua has the potential for development as a botanical insecticide.