The aim of this study was to investigate the efficiency of four pesticides against the whitefly, Bemisia tabaci, infesting squash plants during the two growing season, 2017 and 2018, under field conditions. Data show that the reduction percentages of the white fly, B. tabaci populations on squash plant during season 2017 caused by Lambda cyhalothrin, Thiamethoxam, Azadirachtin and Beauveria bassiana were 86, 81.5, 72.25 and 86.66%, respectively, as mean residual effect. While, the initial reduction percentages for these pesticides were 98, 96, 93 and 0%, respectively. The general mean percentages of reduction caused by Lambda cyhalothrin, Thiamethoxam, Azadirachtin and B. bassiana were 92, 88.75, 82.63 and 90.33%, respectively. The efficiency of the tested pesticides on white fly could be arranged according to their percentages of reduction in infestation in the follows order: Lambda cyhalothrin > B. bassiana > Thiamethoxam > Azadirachtin, respectively. Data also show that all the tested pesticides significantly decreased the number of the white fly, B. tabaci in an irregular way compared to the untreated control. Data also cleared that all the tested pesticides caused decrease in White fly populations till 11th day after treatment. The general mean numbers of the white fly, B. tabaci were 18.4, 27.6, 35.8 and 20 individuals/ sample for Lambda cyhalothrin, Thiamethoxam, Azadirachtin and B. bassiana, respectively, comparing with 211.6 individuals/sample in control group.