Abstract: Intra-guild predation is widespread in the aphid natural enemy communities,and the eggs are mostly the intra-guild prey. When and what kinds of food is influential on the larval growth until imagoes of Chrysopa pallens from crop fields in arid ecosystems in Xinjiang were investigated,and the growth and survival parameters of C.pallens were observed and compared based on the different larval stages (from neonate to the 4^th instar) and the different kinds of food (cotton aphids,cotton aphids plus 7-spot ladybird Cocinellina septempuntata eggs,and 7-spot ladybirds' eggs. The results showed that there was a significant interaction between foot kinds and feeding stages. Survival of C.pallens from the larval stage to the imago stage performed a similar pattern,and it was higher when fed with“aphids”and “aphids plus 7-spot ladybird eggs” than with“7-spot ladybird eggs”. The survival rate was lower with feeding stage treatments from neonate than from the 4th instar larvae. The results of this study suggested that it was difficult to accomplish the growth of C.pallens larvae either from neonate stage or imago stage by feeding with C.septempuntata eggs only.

Key words: Chrysopa pallens, larval development, Cocinellina septempuntata, population dynamic variation, biological control