A study was conducted in the Biological Control Unit College of Agriculture – University of Baghdad (Abu-Ghraib). Results indicated that the predation rates of egg stage were 66.5 and 66.3 for both species respectively with no significant differences at 0.05%. Predation rates of crawlers for both mealy bug species were 47.9 and 38.7 respectively while 2.4 and 1.9, respectively for adults. Results of statistical analysis indicated the variation of predation rates according to the prey stage and species with significant differences. Results of this study also revealed the differences in consumption depending the prey phase and the predators. The functional response of the natural enemies towards its preys considered as an important indicators of its success or failure in biological control programs. The predator N. viridis followed the second mode of functional response according to the figures and tables obtained which means that the mentioned predator is able to organize the population of mealy bug at appropriate environmental conditions.