The effects of five insecticides namely chlorpyrifos, dichiorvos, malathion, permethrin and pirimiphos- methyl was tested in vitro on the six larval instars of Corcyra cephalonica St Based on the LC50 values, the order of susceptibility of the different larval instars was 2 > 1 >3>4>5 >6 while for dichiorvos it was 1 > 2 > 5 > 4 > 5 > 6 . The order for malathion, permethrin and pirimiphos-methyl was 1 >2>3>4> 6 >5. The order of relative toxicity of the five insecticides was dichiorvos >chlorpyrifos > permethrin > pirimiphos-methyl > malathion for the second to the fifth instar, while for the first and sixth instar it was dichiorvos > pirimiphos-methyl > malathion for the second to the fifth instar, while for the first and sixth instar it was dichiorvos > pirimiphos-methyl > permethrin > chlorpyrifos > malathion, and dichiorvos > permethrin > chlorpyrifos > pirimiphos-methyl > malathion, respectively. Dichiorvos is recommended to replace malathion for the control of certain species of storedproduct pests.