Gilpinia hercyniae, the European spruce sawfly, was first found in North America near Hull, Quebec, in 1922 (Rose and Lindquist 1985). By 1930, severe damage was occurring in spruce stands in the Lower St. Lawrence–Gaspé region of Quebec. Population levels exploded, and further damage subsequently occurred in New Brunswick and the northeastern United States (Balch 1936a, b, 1937; Blais 1961). Loss of wood from spruce mortality was estimated at 10 million cubic metres (Rose and Lindquist 1985), but by the mid-1980s pest numbers on all species of spruce in Canada from Manitoba to the Atlantic Ocean and in adjacent parts of the United States had become relatively low under the influence of spontaneous virus disease and introduced parasites. In Newfoundland, control was helped by the introduct