Canadian Forest Service Publications
A disease of the European spruce sawfly, Gilpinia hercyniae (Htg.), and its place in natural control. 1944. Balch, R.E.; Bird, F.T. Scientific Agriculture 25:65-80.
Issued by: Great Lakes Forestry Centre
Catalog ID: 34304
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The European spruce sawfly, Gilpinia hercyniae (Htg.), was apparently introduced to Canada at least several decades ago (1). When first dis covered in 1930, a large outbreak had already developed. The history of this outbreak has been described (2, 3). It reached its peak about 1938, when some 12,000 square miles were estimated as being heavily infested. During the next few years the numbers of the insect declined, until by 1943 no important defoliation was being caused. The decline of the outbreak coincided with the appearance of high percentages of larval mortality due to disease. This paper will discuss the evidence that the disease was responsible for the decline of the outbreak. It will also give some preliminary information regarding the nature of the disease pending the completion of further experimental studies to be reported in full later by the junior author.