Growth Reduction and Mortality of Spruce Caused by the European Spruce Sawfly, Gilpinia Hercyniae (Htg.) (Hymenoptera: Diprionidae)

The severe outbreak of the European spruce sawfly, Gilpinia hercyniae (Htg.), in the Gaspe Peninsula ( 3 ) , continued for about ten years following its discovery in 1930.During this period other outbreaks of shorter duration developed in other regions of Quebec and in New Brunswick.The general extent of the damage has been reported in several papers (1, 2, 3, 5,).The purpose of this paper is to show how the defoliation affected the growth of surviving white spruce, Picea glanca (Moench) Voss, and of black spruce, P, mariana (Mill.)B.S.P., and to indicate the final extent of the damage several years after the end of the outbreak.As some of the stands investigated had been affected by a previous outbreak of the spruce budworm, Cbo~istoneura fumiferana (Clem.),comparisons are made of the injury caused by the two defoliators.Reference is also made to the eastern spruce beetle, Dend~octonus piceaperda Hopk., since an outbreak of this species occurred simultaneously with that of the sawfly in the Gaspe.This study is based principally on observations in three districts: the Cascapedia and Ste.Anne watersheds in the Gaspe Peninsula; Park Reserve Township, Kamouraska County, P.Q.; and Young's Brook, York County, N.B.