This work highlights the study of Lepidosaphes beckii (Newman, 1869) (Homoptera Diaspididae) population dynamics as well as the impact of its external parasite Aphytis lepidosaphes Compere, 1955 (Hymenoptera Aphelinidae) in an orange orchard in Rouiba (Algeria). A year period study shows that L. beckii has three generations per year: the first is the autumnal generation; the second is through the spring and the third throughout summer. Moreover, this cochineal presents a very strong affinity for the central part of the trees and the lower side of the tree leaves which offers optimal conditions for its development. Aphytis lepidosaphes also develops three generations per year: in autumn, spring and summer, matching perfectly the three generations of its host. The parasite can be found where its host is abundant (plentiful). The global parasitism rate records is 22.54% for L. beckii, this rate remains weak to control the cochineal populations.