Leaves of bestachia and dedonia plants were extracted using two solvents, water and acetone at two concentrations 5 & 10%, and tested under laboratory conditions (32 ±2 °C, 55 – 65% relative humidity) against the third larval instar of the European corn borer, Ostrinia nubilalis (hubn.) [lepidoptera: pyralidae]. Dedonia extract in acetone at 10% concentration achieved the highest efficacy as antifeedant as well as growth inhibitory for O. nubilalis. Among all the extracts bestachia extract in water 10% recorded the lowest rate in food consumption, while bestachia extract in acetone 10% was the least efficacy in conversion the ingested food. Dedonia extract in acetone 10% had the highest effect on larval, pupal and adult durations, pupal weight and percentage of malformed pupae and adults. Some extracts proved to be promising on responses of acetyl choline estrase (Ache), trehalse and protease on 3rd larval instar of O. nubilalis. Generally, plant extracts have an effect on the biochemical responses of O. nubilalis and subsequently it may be considered to be safe and promising agents for the said pest control.