Laboratory experiments were carried out to study the influence of different mealybug species as preys on the biological aspects of Rodolia cardinalis (Mulsant) in the insectary of the Economic Entomology, Faculty of agriculture, MansouraUniversity.   The larval stage of the predator R. cardinalis when reared at 24±1˚c and fed on the third nymphal instars of Icerya purchase Mask., Icerya aegyptiaca Douglasand Icerya seychellarum (Westwood)lasted an average of 14.5±0.60, 11.8±0.34 and 16.6±0.55 days, respectively. The average of the total consumption for larval instars at 24±1˚c and fed on I. purchasi, I. aegyptiaca and I. seychellarum as preys reached 68.90±4.01, 60.50±2.18 and 42.65±1.77 individuals. Meanwhile, results indicated that, the highest total consumption for the predator larvae during its larval stages when fed on I. purchasi followed by I. aegyptiaca and I. seychellarum with significant differences. The calculated biomass from (carbohydrates, lipids and protein) consumed by a larva when fed on I. purchasi, I. aegyptiaca and I. seychellarum reached an average of (88.88, 85.44 and 49.61 mg), (80.47, 77.44 and 45.98 mg) and (49.90, 49.05 and 28.15 mg), respectively. The adult longevity for female and male when reared at 24±1˚c and reared on the third nymphal instar of I. purchasi, I. aegyptiaca and I. seychellarum lasted an average of (40.5±2.25 and 26.8±1.72 days), (46.4±2.12 and 29.0±2.09 days) and (32.5±2.60 and 20.8±1.8 days), respectively. The average of the total consumption for adult female reached 263.2±11.25, 328.2±10.90 and 208.7±6.88 individuals/ female when fed on I. purchasi, I. aegyptiaca and I. seychellarum, respectively, with highly significant differences. The calculated biomass from (carbohydrates, lipids and protein) consumed by one predator female during its longevity reached (339.53, 326.37 and 189.5 mg), (436.51, 420.10 and 249.43 mg) and (244.18, 240.01 and 137.74 mg) when fed on I. purchasi, I. aegyptiaca and I. seychellarum, respectively, where for the adult male reached (167.57, 161.08 and 93.53 mg), (193.91, 186.62 and 110.81 mg) and (116.65, 114.66 and 65.80 mg), respectively. The highest total consumption for adult female recorded during the ovipostion period especially, when reared on I. aegyptiaca (289.0±10.53 individuals/ female) and resulting, the number of deposited eggs/ female was the highest (354.30±19.90 eggs/ female), it could be concluded that the best mealybug species for rearing R. cardinalis was I. aegyptiaca because the female layed 354.30 eggs/female.