Gilpinia hercyniae, the European spruce sawfly, was first found in North America near Hull, Quebec, in 1922 (Rose and Lindquist 1985).

Population levels exploded, and further damage subsequently occurred in New Brunswick and the northeastern United States (Balch 1936a, b, 1937; Blais 1961).

[2][3][4][5] Loss of wood from spruce mortality was estimated at 10 million cubic metres (Rose and Lindquist 1985),[1] 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 Ontario, the larvae overwinter in cocoons in the litter layer and change into pupae in the spring.

The adults emerge within a month and lay their eggs, the (second-generation) larvae from which feed from mid-August through September.