Nearly 1300 Lathrolestes nigricollis (Thompson) and 900 Grypocentrus albipes Ruthe (Hymenoptera: Ichneumonidae), were released in Quebec, in 1974 and 1975, in an effort to control the birch leaf-miner, Fenusa pusilla (Lep.). The two species of European parasites were liberated in stands of gray birch (Betula populifolia Marsh.) in four localities of the St. Lawrence River Valley. Mating was well observed for L. nigricollis but not for G. albipes, and both male and female progenies were later recovered for the two species. Three generations of parasitoïds, the first of which overwintered, were recorded at the end of the summer in 1975. Establishment of these parasites of F. pusilla is very likely to occur in the near future.