E. pariana (Clerck) overwinters mainly in the pupal stage in south-western British Columbia. The moths emerge in warm periods and can survive severe cold. Parasitism in 1977-78 was by 29 species and totalled 54 percent. Apanteles longicauda (Wesm.), an introduced European Braconid species, comprised 80 percent of the parasites. The host may be an important reservoir for A. longicauda as a parasite of fruit-tree leaf-rollers.