During the growing season of one year, the aetological and reproductive monitoring of imago Agrotis segetum was carried out using light and pheromone traps. It was noted that, under the climatic conditions of the Republic of Moldova, the first years of butterflies and the laying of winter moths were observed in the third decade of April due to the onset of warm, stable spring temperatures. The pest develops in three full generations. The seasonal sex ratio of the pest was determined - the number of males and females of A. segetum was 1,3:0,8. The reproductive capacity of the A. segetum population has been found to depend heavily on the sequence of generations. Thus, for the I generation the breeding potential was 25%, for the II generation - 24%, for the III generation - 51%. It was noted that the cycle of potential in-infestation times of large numbers of females coincided with mass numbers of females matching the main phases of soybean development – start of branching phase, flowering, formation and ripening of beans.