الفهرس 
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Abstract
The adults of C. undecimpunctata and C. vicina isis were collected from maize fields at the experimental research station, Faculty of Agriculture, Mansoura University and reared on the cowpea aphid, Aphis craccivora Koch. Egg clusters which laid by females of each species were removed daily, and monitored until hatching. Newly molted larvae of C. undecimpunctata and C. vicina isis were taken from egg clusters and placed in three rearing units, first unit was Petri dish (9 cm in diameter), second unit was medium ( 19X9.5 X7 cm) and third unit was large (24 X11.5 X9 cm). All units were divided into four groups per instar. Each group were divided into four treatments, first treatment contains the first instar with different densities (3, 6, 9, and 12), second treatment contains the second instar with the same densities (3, 6, 9, 12) third treatment contains the third instar with the same densities (3, 6, 9, and 12) and the last treatment contains the fourth instar with the same densities (3, 6, 9, and 12). All groups provided daily with 0, 25, 50, and 75 individuals of A. craccivora as preys. Four replicates were examined for each one. The obtained results could be concluded as follows: 1. Concerning C. undecimpunctata and C. vicina isis, there were significant variations in the average number of eggs and average number of hatched larvae. 2. Cannibalism was increased with reduced rearing units. 3. In the absence/ presence of prey, there was a significant difference among rearing units of C. undecimpunctata and C. vicina isis . 4. Cannibalism was increased at the fourth larval instar. 5. In the absence/ presence of prey, there was a significant difference among larval instars of C. undecimpunctata and C. vicina isis. 6. Cannibalism was increased with increased larval densities. 7. In the absence/presence of prey, there was a significant difference among larval densities of C. undecimpunctata and C. vicina isis.