Efficient chemical is achieved when insecticides are active against insect pests and safe to natural enemies (parasitoids). In this study the toxicity of four toxicants, Pyriproxifen (10% EC), Imidacloprid (20% SG), Methoxyphenozide (24% SC) and CAPL-2 (96% EC) are used to explore the role of washing insecticides after 1, 12 and 24 hours of application against immature stages of Bemisia tabaci (Genn.) and associated parasitoids (Encarsia lutea Masi. and Eretmocerus mundus Mercet). The washing may be due to natural events (rainfall, mist or dewy) or mechanical reason (any irrigation system causes washing). Statistical analysis was showed that, the tested insecticides have significant differences on two cases of application (unwashed and washed insecticides) against eggs, nymphs of B. tabaci and associated parasitoids in all tested compounds after 1 and 12 hours of washing insecticides, while after 24hr. of insecticidal washing causes non significant difference between two cases except for Pyriproxifen (10% EC) gave significant difference after three times of washing against eggs. This may be due to that compound act as Insect Growth Regulator (IGR). Insecticides washing cause decrease in efficiency of insecticides against the target (pest), but causes passive effect against the parasitoids. The differences value between previous cases of application, in case of eggs range between (11.68-55.57), (17.32-43.48) and (9.77-28.0) after 1, 12 and 24 hr., respectively. But, nymph ranged between (14.49&19.98), (8.41&16.5) and (0.93 & 2.52) after 1, 12 and 24 hr., respectively, while in parasitoid recorded (3.8 & 7.02), (2.68 & 2.97) and (0.1 & 2.3) after 1, 12, 24 hr, respectively.   Toavoid the insecticidal washing must be taken in consideration: 1- Check the metrologistic report and schedule irrigation time of pivot or any irrigation system causes washing the insecticides from plants. 2-  Do not apply the insecticides at expected rainfall, mist or dewy.