The study was performed to declare the effects of temperature and relative humidity on the population density of Aphis nerii, and the parasitoids, Diaeretiella rapae and Aphidius sp. at two districts, Zagazig and Mansoura (Sharkia and Dakahlia Governorates, respectively) throughout two seasons, 2005-2006 and 2006-2007 on Difla plants. The results indicated a highly significant positive correlation between temperature and population density of A. nerii in the second seasons at the two districts, while relative humidity showed negative significant at Mansoura district in the last season. On the other hand, the data cleared highly significant correlation between temperature and D. rapae during the two seasons at the two districts. Results indicated a highly negative significant between temperature and Aphidius sp at Mansoura district during two seasons. A significant negative correlation was obtained between the two parasitoids, D. rapae & Aphidius sp and A. nerii during two seasons at two districts. The parasitoid, D. rapae accepted the stages of oleander aphid, A. nerii, with average number of mummies per female parasitoid 64.2. Results indicated insignificant effect on incubation period of eggs, larval and pupal durations between the two parasitoids, D. rapae and Aphidius sp., but the total developmental period of two parasitoids had a significant effect on A. nerii, the averages were 19.38±0.57 and 22.09±0.54 with D. rapae and Aphidius sp., respectively. The work showed that leaf -arrival time decreased with increasing host density. Meanwhile, the first sting-time, numbers of oviposition and mummies increased with increasing host density.