Culex pipiens (L.) (Diptera: Culicidae) is the most important medical insect in many parts of the world. Biological and natural chemicals have many advantages over the traditional ones in case of mosquito control. Radiant, Isomectin and Nimbecidine insecticides were evaluated for their efficiency against the wild and laboratory individuals of late 3^rd instar larvae of Culex pipiens at different concentrations and two periods of exposure under laboratory conditions. Results revealed that the mortality percentage was increased gradually with increasing the insecticide concentrations and the mortality percentage showed significant differences between concentrations and control. Moreover, results showed that mortality percentage increased with increasing the period of insecticide exposure. Tolerance and lab strain of Culex pipiens to insecticides showed that wild individuals were more tolerant than lab individuals to Radiant and Isomectin, and vice versa with Nimbecidine. Results revealed also that Radiant insecticide was the most effective insecticide against late 3^rd instar larvae of Culex pipiens followed descendingly by Isomectin and Nimbecidine for both wild and lab strains of mosquitoes. Moreover, the toxicity index of the tested insecticides proved the high toxicity of Radiant than Isomectin and Nimbecidine. Toxicity index of Radiant at LC₅₀ showed such superior efficacy (100%) followed by Isomectin and Nimbecidine.