In the two-year period 1989-90, researches were carried out, with the aim of monitoring adults (by means of sexual female pheromone lures), and studying the bioetology, population dynamics and extent of damage caused by the Lepidoptera Gelichiidae Phthorimaea operculella (Zeller) to medium to late maturing_potato crops (cv. Monalisa). The studies were performed in the po at.-gromng environment of Northern Latium. and the following data were thereby evidenced: the species completes four generations from May to September; overwintering takes place t>oth Inside the tubers left in the field after harvesting, and in various shelters: among the several limiting biotic factors, the Hymenoptera Braconidae Diadegma pulchripes (Kokujev) is worth mentioning; the severest damage occurs in medium-late or late maturing cuftivars: early maturing cuftivars, on the contrary, are not attacked by the Gelechiidae; finally, some pieces of aeronomical advice are supplied as to infestation control methods; among these, rational crop rotation is judged important. none