Abstract: In this paper data are presented about the life cycle and the natural mortality of theolive moth, Prays oleae (Bern.), in Trás-os-Montes region (northeast Portugal). Observationswere carried out in an olive grove situated near Mirandela, during the period of 1993 to 2002, ontrees of the Cobrançosa, Verdeal Transmontana and Madural varieties, about 35 years old, nonirrigatedand non- sprayed. The flight phenology of the insect was studied by means ofpheromone delta traps, while that of the immature stages, and also the rates of predation and themortality due to intraspecífic competition, was studied by collecting samples of leaves, flowerclusters and fruit. To evaluate the mortality due to premature fall of fruit, samples of fallen fruitwere collected, while the rates of parasitism and the respective parasitoid species weredetermined by rearing larvae and pupae of each of the three generations of the pest. Adult malecaptures were recorded from April to May, for the first flight period, from May to July for thesecond, and from September to December, for the third. The cumulative number of captures pertrap ranged between 442 and 1586, for the first flight, 926 and 2650 for the second, and 258 and1499 for the third. The predation rates of eggs varied from 14.0% to 25.0 %, in the leafgeneration, 3.2% to 10.7% in the flower generation and 9.7% to 34.0% in the fruit generation,while parasitism rates were from 7.4% to 46.7% in the leaf generation, 25.4% to 56.5% in theflower generation, and 21.3% to 61.9% in the fruit generation. Ten species of Hymenopteraparasitoids were identified. The mortality due to the intraspecific competition varied between18.4% and 24.5% of the total population, while that due to the premature fall of fruit ranged from57.9% to 89.5%.