it is host specific and there are some rare geometrid moths in the area. The fly has become successfully established in Massachusetts, and the level of parasitism of the moth larvae had reached 20-50% by 2015, after thousands of Cyzenis albicans were released at 17 sites in New England. In its native range, C. albicans has very little impact on populations of winter moth, and its success in biological control of this invasive pest in Canada and the United States was difficult to predict; soil conditions seem to have been of importance, and there may have been a dearth of natural enemies to prey on the flies, enabling them to become established. A recent study on the mortality factors affecting C. albicans puparia in Massachusetts shows that, in fact, C. albicans experiences heavy mortality from generalist pupal predators and parasitoids. References Diptera of Europe Insects described in 1810 Tachinidae