An experiment was conducted to test the insecticidal efficacy of five meliaceous plant extracts against third instar larvae of Spilarctia obliqua Walker (Lepidoptera : Arctidae) under the laboratory conditions. The bioefficacy of five meliaceous plant materials viz., Azadirachta indica A. Juss. and Melia azedarach Linn. (leaves, bark and seed kernel), Swietenia mahagoni (L.) Jacq. (leaves) and Soymida febrifuga (Roxb.) A. Juss. and Toona ciliate M.Roem (bark) were prepared with the help of the soxhlet apparatus under the laboratory conditions and neem by product Azedirachtin and one untreated control used for detail study. The laboratory trial was done in three glass petridishes (10 cm diameter) and replicated thrice by using each selected extracts per petridish. To record the mortality of ten larvae of Spilarctia obliqua were released inside each pair of petridishes and allow them to remain for 24 hours. These petridishes were kept as such under control conditions and mortality count was taken after 6, 12, 24 hours of exposure. The data depicted in Table.1 indicated that Azedirachtin registered highest mortality (80.87%) to the 3rd instars larvae of Spilarctia obliqua Walk., when compared to other meliaceous plant extracts. NSKE (77.50) > MSKE (72.82 ) > Melia leaf extract (68.46) > Neem leaf extract ( 67.90) > Toona bark extract (66.35) > Melia bark extract (59.54) > Neem bark extract (58.41) > Soymida bark extract (55.81) > Swietenia leaves extract (46.80) > control (12.29), respectively.