Algerian oak forests, extending over the entire northern littoral region, are attacked episodically by many defoliating Lepidoptera, of which Lymantria dispar (Linnaeus, 1758) (Lepidoptera Limantriidae) is the most widespread. In our study we aim to highlight the action of the changes of trophic factors on the dynamics of the population of Lymantria dispar through field inventory methods. Namely: the eggs counting by the line-transect method, picking of the eggs, control of eggs quality. Carried out on two stations in the Kabylie region (Jijel), in the forest of Béni Ider El M’sid (Taher) and that of the Ouled Djendjen Canton Boudouda (Texanna). The obtained results show that Texanna station is distinguished by a very high non-viable egg rate compared to Taher station, this is caused by the difference between the phenology of Lymantria dispar and the host tree which is affected in its foliage by various factors whose altitude is one of these factors